Lateral pararectal versus transrectal stoma placement for prevention of parastomal herniation

  • Review
  • Intervention

Authors


Abstract

Background

A parastomal hernia is defined as an incisional hernia related to a stoma and belongs to the most common stoma-related complications. Many factors concerning the operative technique which are considered to influence the incidence of parastomal herniation have been investigated. However, it remains unclear whether the enterostomy should be placed through or lateral to the rectus abdominis muscle in order to prevent parastomal herniation and other important stoma complications for people undergoing abdominal wall enterostomy.

Objectives

To assess if there is a difference regarding the incidence of parastomal herniation and other stomal complications, such as ileus and stenosis, in lateral pararectal versus transrectal stoma placement in people undergoing elective or emergency abdominal wall enterostomy.

Search methods

In October and November 2012 we searched for all types of published and unpublished randomized and non-randomized studies with no restriction on language, date or country (search dates in brackets). We searched the bibliographic databases The Cochrane Library (4 October 2012), MEDLINE (1 October 2012), EMBASE (10 October 2012), LILACS (29 November 2012), and Science Citation Index Expanded (4 October 2012). We also searched the reference lists of all relevant studies and the trial registers ClinicalTrials.gov (9 October 2012), World Health Organization (WHO) International Clinical Trials Registry Platform (ICTRP) Search Portal (10 October 2012), as well as three additional trial registers not included in the ICTRP (27 November 2012).

Selection criteria

Randomized and non-randomized studies comparing lateral pararectal versus transrectal stoma placement with regard to parastomal herniation and other stoma-related complications.

Data collection and analysis

Two authors independently assessed study quality and extracted data. Data analyses were conducted according to the recommendations of The Cochrane Collaboration and the Cochrane Colorectal Cancer Group (CCCG). Quality of evidence was rated according to GRADE (Grading of Recommendations Assessment, Development and Evaluation).

Main results

Nine retrospective cohort studies with a total of 761 participants met the inclusion criteria. All included studies reported results for the primary outcome (parastomal herniation), and one study also reported data on one of the secondary outcomes (stomal prolapse). None of the included studies compared the two interventions with regard to other secondary outcomes.

There was neither a significant difference in terms of the risk for parastomal herniation (risk ratio (RR) 1.29; 95% confidence interval (CI) 0.79 to 2.1) nor with regard to the occurrence of stomal prolapse (RR 1.23; 95% CI 0.39 to 3.85). An I² value of 65% indicated substantial statistical heterogeneity in the meta-analysis.

Authors' conclusions

The poor quality of the included evidence does not allow a robust conclusion regarding the objectives of the review. This review highlights a clear uncertainty as to the relative merits of either approach. There is a need for randomized trials to evaluate the effectiveness of the lateral pararectal versus the transrectal approach in preventing parastomal herniation and other stoma-related morbidity in people requiring enterostomy placement.

Résumé scientifique

Pararectal latéral par rapport à une mise en place de stomie transrectale pour la prévention d’hernies parastomales

Contexte

Une hernie parastomale est définie comme une hernie incisionnelle liée à une stomie et est la complication la plus courante relative à la stomie. De nombreux facteurs des techniques opératoires, qui sont considérés comme ayant une influence sur l'incidence d’hernies parastomales, ont été étudiés. Cependant, on ignore si l'enterostomie devrait être placée via ou latéralement au muscle grand droit de l’abdomen afin de prévenir une hernie parastomale et d'autres complications importantes de la stomie chez les patients subissant une enterostomie de la paroi abdominale.

Objectifs

Évaluer s'il existe une différence concernant l'incidence d’hernie parastomale et d'autres complications de la stomie, telles que la sténose d'iléus latérale amyotrophique, entre un pararectal latéral et un pararectal transrectal de la stomie chez les patients subissant une enterostomie de la paroi abdominale élective ou d’urgence.

Stratégie de recherche documentaire

En octobre et novembre 2012, nous avons recherché toutes les études randomisées publiées et non publiées et non randomisées, sans aucune restriction concernant la langue, la date ou le pays (les dates de recherche entre parenthèses). Nous avons effectué des recherches dans les bases de données bibliographiques La Bibliothèque Cochrane (4 octobre 2012), MEDLINE (1er octobre 2012), EMBASE (10 octobre 2012), LILACS (29 novembre 2012), et Science Citation Index Expanded (4 octobre 2012). Nous avons également consulté les références bibliographiques de toutes les études pertinentes et les registres d'essais ClinicalTrials.gov (9 octobre 2012), l’Organisation Mondiale de la Santé (OMS), International Clinical Trials Registry Platform (ICTRP,) Search Portal (10 octobre 2012), ainsi que trois registres d'essais supplémentaires non inclus dans l'ICTRP (27 novembre 2012).

Critères de sélection

Essais randomisés et non randomisés comparant une pararectal latérale par rapport à une mise en place transrectale de la stomie concernant une hernie parastomale et les autres complications relatives à la stomie.

Recueil et analyse des données

Deux auteurs ont indépendamment évalué la qualité des études et extrait les données de manière indépendante. Les analyses des données ont été réalisées conformément aux recommandations de la Collaboration Cochrane et du registre du groupe Cochrane sur le cancer colorectal (du groupe Cochrane sur le cancer). La qualité des preuves a été évaluée selon le système GRADE (Grading of Recommendations Assessment, Development and Evaluation).

Résultats principaux

Neuf études de cohortes rétrospectives portant sur un total de 761 participants remplissaient les critères d'inclusion. Toutes les études incluses rapportaient des résultats pour le critère de jugement principal (hernie parastomale) et une étude a également rapporté des données sur l'un des critères de jugement secondaires (prolapsus de la stomie). Aucune des études incluses ne comparaient les deux interventions concernant les autres critères de jugement secondaires.

Il n'y avait aucune différence significative en termes de risque d’hernie parastomale (risque relatif (RR) 1,29; intervalle de confiance (IC) à 95% de 0,79 à 2,1), ni en termes de survenue d'un prolapsus de la stomie (RR 1,23; IC à 95% 0,39 à 3,85). La méta-analyse indiquait une hétérogénéité statistique importante égale à 65%.

Conclusions des auteurs

La mauvaise qualité des preuves ne permet pas une conclusion rigoureuse concernant les objectifs de la revue. Cette revue met en évidence une incertitude quant aux mérites relatifs à l'une ou à l'autre approche. Des essais randomisés sont nécessaires pour évaluer l'efficacité de la pararectal latérale par rapport à l'approche transrectale dans la prévention d’hernie parastomale et les morbidités relatives à la stomie chez les patients nécessitant une mise en place d’enterostomie.

Plain language summary

Lateral pararectal versus transrectal stoma placement for prevention of parastomal herniation

A parastomal hernia is defined as an incisional hernia related to a stoma and belongs to the most common stoma-related complications. Many factors concerning the operative technique that are considered to influence the incidence of parastomal herniation have been investigated. However, it remains unclear whether the enterostomy should be placed through or lateral to the rectus abdominis muscle in order to prevent parastomal herniation and other important stoma complications for patients.

Nine retrospective cohort studies with a total of 761 participants met the inclusion criteria. All included studies reported results for the primary outcome (parastomal herniation), and one study also reported data on one of the secondary outcomes (stomal prolapse). None of the included studies compared the two interventions with regard to other secondary outcomes. There was neither a significant difference in terms of the risk for parastomal herniation nor with regard to the occurrence of stomal prolapse.

In summary, the quality of the identified evidence is too poor to allow a robust conclusion regarding the objectives of the review. This highlights the need for randomized trials to evaluate the effectiveness of the lateral pararectal versus the transrectal approach in preventing parastomal herniation and other stoma-related and patient-important morbidity in people requiring enterostomy placement.

Résumé simplifié

Pararectal latéral par rapport à une mise en place de stomie transrectale pour la prévention d’hernies parastomales

Une hernie parastomale est définie comme une hernie incisionnelle liée à une stomie et est la complication la plus courante relative à la stomie. De nombreux facteurs concernant les techniques opératoires, qui sont considérés comme ayant une influence sur l'incidence d’hernies parastomales, ont été étudiés. Cependant, on ignore si l'enterostomie devrait être placée via ou latéralement au muscle grand droit de l’abdomen afin de prévenir une hernie parastomale et d'autres complications importantes de la stomie chez les patients.

Neuf études de cohortes rétrospectives portant sur un total de 761 participants remplissaient les critères d'inclusion. Toutes les études incluses rapportaient des résultats pour le critère de jugement principal (hernie parastomale) et une étude a également rapporté des données sur l'un des critères de jugement secondaires (prolapsus de la stomie). Aucune des études incluses ne comparaient les deux interventions concernant les autres critères de jugement secondaires. Il n'y avait aucune différence significative en termes de risque d’hernie parastomale, ni en en termes de survenue de prolapsus de la stomie.

En résumé, la qualité des preuves identifiées est trop faible pour permettre une conclusion solide concernant les objectifs de la revue. Ce qui souligne le besoin d'essais randomisés pour évaluer l'efficacité de la pararectal latérale versus l'approche transrectale dans la prévention d’hernie parastomale, les complications relatives à la stomie, la morbidité chez les patients nécessitant une mise en place d’enterostomie.

Notes de traduction

Traduit par: French Cochrane Centre 14th January, 2014
Traduction financée par: Minist�re Fran�ais des Affaires sociales et de la Sant�, Instituts de Recherche en Sant� du Canada, Minist�re de la Sant� et des Services Sociaux du Qu�bec, Fonds de recherche du Qu�bec Sant� et Institut National d'Excellence en Sant� et en Services Sociaux

Summary of findings(Explanation)

Summary of findings for the main comparison. Lateral pararectal versus transrectal enterostomy placement for parastomal herniation (prevention)
  1. 1 Health problem: patients requiring enterostomy (of any type, permanent or temporary) placement, thus being at risk for developing parastomal herniae and other stoma-related complications.
    2 In three studies, the presence of parastomal hernia was assessed by clinical examination and CT scanning (Cingi 2006, Ortiz 1994, Williams 1990). In the remaining studies, patients were clinically examined, e.g. in stoma therapy or outpatient clinic at follow-up visits, and the findings were documented in the patient chart.
    3 The quality of evidence was further downgraded by one level from low to very low for the following reasons: 1. There are widely differing estimates of the intervention effect (i.e. heterogeneity) across studies, but we failed to identify a plausible explanation. Possible reasons could be the lack of standardization of the surgical procedure as well as the absence of a uniform definition and detection method of parastomal hernia. 2.1 The total number of events is less than 300 (a threshold rule-of-thumb value) (based on: Mueller et al. Ann Intern Med. 2007;146:878-881 <http://www.annals.org/cgi/content/abstract/146/12/878>) 2.2 95% confidence interval around the estimate of effect includes both 1) no effect and 2) appreciable benefit or appreciable harm. 3. Risk of bias assessed using the Newcastle-Ottawa Scale is considered high in the included studies, especially with respect to selection bias and incomplete outcome data.

Lateral pararectal versus transrectal enterostomy placement for parastomal herniation (prevention)
Patient or population: People requiring enterostomy placement1
Settings: not specified
Intervention: lateral pararectal versus transrectal enterostomy placement
OutcomesIllustrative comparative risks* (95% CI)Relative effect
(95% CI)
No of Participants
(studies)
Quality of the evidence
(GRADE)
Comments
Assumed riskCorresponding risk
Control Lateral pararectal versus transrectal enterostomy placement
Parastomal hernia
clinical examination and/or CT scanning2
Follow-up: 0.1-596 months
196 per 1000 253 per 1000
(155 to 412)
RR 1.29
(0.79 to 2.1)
761
(9 studies)
⊕⊝⊝⊝
very low 3
 
Stomal prolapse
clinical examination (findings documented in a standard pro forma)
Follow-up: mean 110.4 months
78 per 1000 96 per 1000
(30 to 299)
RR 1.23
(0.39 to 3.85)
145
(1 study)
⊕⊝⊝⊝
very low
 
Ileus/stenosis/obstruction - not measured  Not estimable   
stomal necrosis - not measured  Not estimable   
stomal retraction - not measured  Not estimable   
stoma-related skin irritation - not measured  Not estimable   
other stoma-related morbidity - not measured  Not estimable   
The corresponding risk (and its 95% confidence interval) is based on the assumed risk in the comparison group and the relative effect of the intervention (and its 95% CI).
CI: Confidence interval; RR: Risk ratio;
GRADE Working Group grades of evidence
High quality: Further research is very unlikely to change our confidence in the estimate of effect.
Moderate quality: Further research is likely to have an important impact on our confidence in the estimate of effect and may change the estimate.
Low quality: Further research is very likely to have an important impact on our confidence in the estimate of effect and is likely to change the estimate.
Very low quality: We are very uncertain about the estimate.

Background

Description of the condition

A parastomal hernia is an incisional hernia related to a stoma (Pearl 1989). Parastomal herniation is one of the most common stoma-related complications (Carne 2003). On physical examination, a parastomal hernia is diagnosed if bulging restricted to the peristomal area occurs during the Valsalva maneuver and a fascial defect can be palpated (Cingi 2006; Sjodahl 1988). On a computed tomography (CT) scan, a parastomal hernia can be described as "a loop of intestine or any abdominal organ, as well as preperitoneal fat, protruding through the defect alongside the ostomy" (Cingi 2006).

The incidence of parastomal hernias varies greatly between studies, but most likely ranges from 30% to 50% depending on the length of follow-up and on the type of enterostomy (Israelsson 2008). The consequences and implications of parastomal hernias are highly relevant for patients. Many patients complain of pain, suffer from an impaired body image, and have increasing difficulties to apply the stoma bag properly leading to leakage and skin irritation (Martin 1996; Ripoche 2011). In rare cases, bowel incarceration occurs requiring emergency surgery (Cuthbertson 1977). In addition, stomal herniation necessitating reoperation and hospitalization has a negative socioeconomic impact, especially since recurrence rates after surgical correction are high (Israelsson 2008; Tekkis 1999), ranging up to 50% within an average of six months after operative repair (Ripoche 2011).

Description of the intervention

Two interventions were compared, placement of the stoma lateral to versus through the rectus abdominis muscle (lateral pararectal versus transrectal).

Lately, mesh reinforcement of the stoma has been advocated to lower the incidence of parastomal herniation. Two recent systematic reviews of three RCTs (Hammond 2008; Janes 2004; Janes 2009; Serra-Aracil 2009) with a total of 129 patients have approached the question, whether prophylactic implantation of prosthetic mesh concurrently with the index operation could reduce the occurrence of parastomal herniation (Shabbir 2012; Wijeyekoon 2010). Meta-analysis showed that mesh reinforcement was associated with a reduction in parastomal herniation as compared to conventional stoma formation with no excess morbidity.

How the intervention might work

Lateral pararectal stoma placement may have a different incidence of parastomal herniation in comparison to transrectal stoma formation. Since the transrectal stoma is surrounded by the thick muscle layers of the rectus abdominis muscle, one could expect a tighter fit and a reduced incidence of parastomal herniation due to the muscle contractions. On the other hand, one could argue that preserving the integrity of the rectus abdominis muscle and its sheath, as it is the case in lateral pararectal stomas, minimizes anterior abdominal wall disruption and consequently reduces the risk of parastomal hernia (Evans 2011; Stephenson 2010).

Why it is important to do this review

Parastomal herniation is one of the most common complications after stoma placement. Since parastomal hernias often have a negative impact on the patient’s health and quality of life, the operative techniques should be optimized in order to prevent this postoperative complication. The need for prevention becomes even more relevant in the light of the high recurrence rates after operative correction of parastomal hernia, ranging from 50% to 76% after aponeurotic repair and from 24% to 86% after relocation, respectively (Israelsson 2008). Patients with a permanent stoma, for example after abdomino-perineal resection for low rectal cancer, especially suffer from the morbidity caused by parastomal herniation. Many surgical approaches have been attempted and propagated. However, there is still no clinical evidence from RCTs on which is the best location site for a stoma. We therefore assumed clinical equipoise in regard to the question where a stoma should be located in relation to the rectus abdominis muscle.

Two studies showed a significant reduction in the incidence of parastomal herniation if the stoma was sited through the rectus abdominis muscle versus a location lateral to the muscle (Eldrup 1982; Sjodahl 1988). One prospective uncontrolled cohort study including 72 consecutive, unselected patients described a novel anatomical approach to stoma formation, the lateral rectus abdominis positioned stoma (LRAPS), which involves minimal anterior abdominal wall disruption. The authors presented parastomal herniation rates of 5% (3/62) and 10% (4/41) at a follow-up of one year and two years, respectively (Evans 2011; Stephenson 2010), which is consistent with a relevant reduction in parastomal hernia rate when compared to data from the literature (Robertson 2005).

In view of these controversies, a systematic review of the available non-randomized studies (NRS) is considered justified to efficiently integrate existing information and provide data for rational decision making, as well as to gain insight into treatment effects and potential adverse outcomes.

Another reason for conducting this systematic review was to evaluate the strengths and weaknesses of the available NRS in order to examine the case for undertaking randomized trials. This means that the findings of our review could be applied to shape the design of prospective RCTs (Reeves 2011).

Objectives

To assess if there is a significant difference regarding the incidence of parastomal herniation and other stomal complications, such as ileus and stenosis, in lateral pararectal versus transrectal stoma placement.

Furthermore, it has to be determined whether a lower parastomal herniation rate goes along with an increased incidence of ileus and stenosis.

Methods

Criteria for considering studies for this review

Types of studies

Randomized and non-randomized studies were eligible. In the absence of randomized studies, non-randomized studies were included, as stated in our review protocol, if they met the inclusion criteria below and compared lateral pararectal versus transrectal enterostomy formation. Studies only reporting data on transrectal (for example Carlstedt 1987; Leenen 1989) or lateral pararectal enterostomies (for example Stephenson 2010) were excluded.

Types of participants

All individuals receiving a temporary or permanent abdominal wall enterostomy for any reason in either the elective or the emergency setting were included with no regard to the underlying disease.

Types of interventions

Two interventions were compared: lateral pararectal versus transrectal stoma placement.

Types of outcome measures

Primary outcomes

Occurrence of parastomal herniation.

Secondary outcomes
  1. Stoma-related morbidity, especially stenosis, obstruction, prolapse, necrosis, retraction, fistulization, and skin irritation;

  2. Stoma-related mortality.

Search methods for identification of studies

In October and November 2012 we searched for all types of published and unpublished randomized controlled trials (RCTs) and non-randomized studies (NRS) with no restriction on language, date, or country. We undertook a broad search approach due to the expected scarcity of randomized controlled trials regarding the review objective. Therefore we did not apply any kind of search filter for study types on our searches.

The Trials Search Co-ordinator of the Cochrane Colorectal Cancer Group (CCCG) peer-reviewed the search strategy developed for MEDLINE and was asked for the resources to be searched.

Electronic searches

Studies were identified by searching the following bibliographic databases:

  • MEDLINE (via PubMed), including subsets "as supplied by publisher" and "in process" (1946 to 1 October 2012), see Appendix 1

  • EMBASE (via OvidSP) (1980 to 2012 Week 40), see Appendix 2

  • The Cochrane Library (via Wiley), see Appendix 3

    • Cochrane Database of Systematic Reviews (CDSR) (Issue 9, 2012)

    • Database of Abstracts of Reviews of Effects (DARE) (Issue 3, 2012)

    • Cochrane Central Register of Controlled Trials (CENTRAL) (Issue 9, 2012)

    • Cochrane Methodology Register (Issue 3, 2012), Health Technology Assessment Database (Issue 3, 2012)

    • NHS Economic Evaluation Database (NHSEED) (Issue 3, 2012)

  • Science Citation Index Expanded (via Web of Knowledge) (1987 to 4 October 2012), see Appendix 4

  • LILACS (via VHL Search) (1982 to 29 November 2012), see Appendix 5

The CCCG Trials Register was not searched separately as it is fully included in CENTRAL.

Searches were adapted to each database and carried out using the specific controlled vocabulary of each database, if available (MeSH terms for MEDLINE and The Cochrane Library, Emtree terms for EMBASE, DeCS terms for LILACS), as well as free text words.

Unpublished and ongoing trials were searched for using free text words in the following trial registers.

    • Australian New Zealand Clinical Trials Registry (imported on 9 October 2012)

    • ClinicalTrials.gov (imported on 9 October 2012)

    • European (EU) Clinical Trials Register (imported on 9 October 2012)

    • ISRCTN (imported on 9 October 2012)

    • Brazilian Clinical Trials Registry (imported on 18 September 2012)

    • Chinese Clinical Trial Registry (imported on 18 September 2012)

    • Clinical Trials Registry – India (imported on 18 September 2012)

    • Clinical Research Information Service - Republic of Korea (imported 18 September 2012)

    • Cuban Public Registry of Clinical Trials (imported on 18 September 2012)

    • German Clinical Trials Register (imported on 18 September 2012)

    • Iranian Registry of Clinical Trials (imported on 18 September 2012)

    • Japan Primary Registries Network (imported on 18 September 2012)

    • Pan African Clinical Trial Registry (imported on 18 September 2012)

    • Sri Lanka Clinical Trials Registry (imported on 18 September 2012)

    • The Netherlands National Trial Register (imported on 18 September 2012)

Registers not included in the ICTRP:

Even though ClinicalTrials.gov is included in the ICTRP, we searched it separately because its search interface allows for a better search than the search interface of ICTRP.

Searching other resources

Reference lists of included studies and relevant reviews identified during the search were screened.

Data collection and analysis

Selection of studies

One author (JH) screened all titles and abstracts of papers identified by the search strategies for relevance. Only clearly irrelevant citations were excluded at this stage. We obtained full copies of all potentially relevant papers. One relevant paper which only existed in Danish was translated by a Danish Cochrane author and physician (Lasse T. Krogsbøll). At this stage two review authors (JH and FH) independently screened the full texts, identified relevant studies and assessed eligibility of studies for inclusion. Any disagreement on the eligibility of studies was resolved by discussion and consensus, or if necessary by a third review author (JM, PK). We excluded all irrelevant records and recorded the reasons for exclusion.

Data extraction and management

JH and FH extracted the data for the review independently. In addition to the outcomes, data on population characteristics (such as sex, age, underlying disease, obesity (BMI > 30 kg/m²)), and type of stoma (ileostomy versus colostomy, end ostomy versus loop ostomy) were collected if available. Data collection forms were customized carefully to the review question being investigated. During the reviewing process the data collection forms were repeatedly revised to enable us to handle the different kinds of information about study findings.

Assessment of risk of bias in included studies

As recommended by Reeves et al. in the Cochrane Handbook for Systematic Reviews of Interventions (Reeves 2011), we applied the Newcastle-Ottawa Scale (NOS) (Wells 2011) for cohort studies to assess the methodological quality of the included studies in the following domains: selection of cohorts, comparability of cohorts, and assessment of outcome. Moreover, we also assessed reporting bias and other bias which are not included in the NOS. In addition, we attempted the use of the Downs and Black Checklist (Downs 1998) for risk of bias assessment which is applicable to both RCTs and NRS and is also recommended by Reeves et al., but we had to conclude that the NOS was easier to use with regard to the included cohort studies. Risk of bias was assessed independently by JH and FH.

Measures of treatment effect

Presence of parastomal herniation as well as the presence of stomal prolapse were treated as dichotomous variables. For dichotomous variables, the risk ratio (RR) was calculated with 95% confidence interval (CI).

Unit of analysis issues

The unit of analysis was each patient recruited into the trials.

Dealing with missing data

We carefully assessed the risk of incomplete outcome data using the NOS. Since all included studies were retrospective cohort studies with the majority published more than 20 years ago, we refrained from contacting the authors for missing data on losses to follow-up and their reasons. However, we discussed the potential impact of missing outcome data (for example due to losses to follow-up or exclusions from analysis) in the discussion section.

Assessment of heterogeneity

The Chi² test was used for assessment of statistical heterogeneity. Statistical significance was determined by a P value of 0.10. Even more relevant than the assessment of heterogeneity is the quantification of its impact on the meta-analysis. Thus, we applied the I² value to quantify the inconsistency of the included studies (Higgins 2011). An I² value less than 40% might not be important; greater values may represent moderate (< 60%), substantial or even considerable (> 75%) heterogeneity. Nonetheless, we were aware of the fact that there is much uncertainty in measures, such as the I² statistic, when there are few studies.

Assessment of reporting biases

Reporting biases occur if the dissemination of research findings is influenced by the nature and direction of trial results. There are several types of reporting bias: publication bias, multiple publication bias, time lag bias, location bias, citation bias, language bias, and outcome reporting bias (Sterne 2011).

We used a comprehensive search strategy including the search of five different trial registers in order to minimize the likelihood of publication bias (see: Electronic searches), but we were aware of the problem that NRS are not consistently indexed in trial registers. Furthermore, we searched LILACS, the most important and comprehensive index of scientific and technical Latin-American and Caribbean literature to diminish the risk of language bias.

We used a funnel plot to assess publication bias in our systematic review (see Figure 1). Publication bias is considered minimum if the plot resembles a funnel with base down. However, we were aware of the fact that asymmetry is difficult to detect with such a small number of included studies (Sterne 2011).

Figure 1.

Funnel plot of comparison: 1 Lateral pararectal versus transrectal enterostomy placement, outcome: 1.1 parastomal hernia.

Data synthesis

From the analysis options in Review Manager version 5.2, we applied the DerSimonian and Laird random-effects model, assuming that the effects being estimated in the different studies are not identical but follow some distribution (DerSimonian 1986). The random-effects model estimates the extent of variation among the intervention effects of the included studies (Higgins 2011).

Subgroup analysis and investigation of heterogeneity

We conducted the following subgroup analysis:

  • ileostomy versus colostomy.

For the following intended subgroup analyses, the required data were not reported in the included studies:

  • obesity (BMI > 30 kg/m²), overweight (BMI > 25 < 30 kg/m²) versus normal weight (BMI > 20 < 25 kg/m²);

  • end versus loop ostomy.

Sensitivity analysis

Sensitivity analysis investigates how the variation in the output of a statistical model depends on the different variations in the inputs of the model. None of the two planned sensitivity analyses could be performed because of the following reasons:

  • Sensitivity analysis based on assessment of standardization of stoma surgery was not performed since there was insufficient evidence of standardization of the surgical interventions in the included studies. For future updates of this review, we will assume standardization of the surgical intervention only if this is explicitly stated by the authors in combination with a detailed description of the applied surgical technique.

  • Sensitivity analysis based on assessment of risk of bias was not performed since the included studies were all at high risk for bias in at least one of the assessed domains and showed very similar risk of bias profiles (see Figure 2; Figure 3; Table 1 ). For future versions of this review, we plan to investigate the robustness of our results through a sensitivity analysis on the basis of the methodological quality of the included studies by defining the following categories: low risk of bias (cohorts truly comparable and at least somewhat representative of the community they were derived from, secure ascertainment of intervention(s) and outcome(s), losses to follow-up of less than 20%); high risk of bias (cohorts not representative or not comparable, intervention(s) or outcome(s) not reliably assessed, losses to follow-up of more than 20%); unclear risk of bias (rating of unclear risk of bias in at least two of these five bias domains).

    Figure 2.

    Risk of bias graph: review authors' judgements about each risk of bias item presented as percentages across all included studies.

    Figure 3.

    Risk of bias summary: review authors' judgements about each risk of bias item for each included study.

    Table 1. Risk of bias summary: review authors' judgements about each quality item using the NOS criteria
    1. A study can be awarded a maximum of one star for each numbered item within the Selection and Outcome categories. A maximum of two stars can be given for Comparability. A maximum of nine stars can be awarded overall.

      Representativeness of the experimental intervention cohort Selection of the control cohort Ascertainment of intervention Demonstration that outcome of interest was not present at start of study Comparability of cohorts on the basis of the design or analysis Assessment of outcome Was follow-up long enough for outcomes to occur Adequacy of follow-up of cohorts
    Cingi 2006     
    Eldrup 1982    
    Leong 1994   
    Londono-Schimmer 1994   
    Ortiz 1994   
    Pilgrim 2010     
    Sjodahl 1988   
    von Smitten 1986    
    Williams 1990   

Results

Description of studies

See: Characteristics of included studies; Characteristics of ongoing studies.

Results of the search

As recommended by the PRISMA statement (Liberati 2009), a study flow diagram (Figure 4) summarizes the study selection process.

Figure 4.

Study flow diagram.

A total of 2831 references were retrieved by the electronic searches (first search run October 2012) of The Cochrane Library (CDSR 29; DARE 7; CENTRAL 15; NHSEED 3), MEDLINE (877), EMBASE (1297), Web of Science (558), and LILACS (45); 1319 duplicates and 1499 clearly irrelevant references, identified by reading titles and abstracts, were excluded. The 13 remaining references were retrieved for further assessment; three (two of them were reports on the same study) of the 13 references from the electronic database search as well as the nine references identified by checking the reference lists of relevant studies and reviews were excluded after reading the full texts (see: Excluded studies) for any of the following reasons (number of studies in brackets):

  • only transrectal stomata (without a lateral pararectal control group) (n = 2);

  • only lateral pararectal stomata (without a transrectal control group) (n = 1);

  • stomal site in relation to the rectus abdominis muscle unclear (n = 8).

The remaining 10 references relating to nine non-randomized studies (NRS) fulfilled our inclusion criteria (see: Included studies).

A total of 46 trials were identified by searching five different trial registers (ClinicalTrials.gov: 22; HKUCTR: 1; UKCTG: 3; UKRNPD: 5; ICTRP: 15). Except for one ongoing single-center RCT (see: Ongoing studies), none of the trials were relevant with regard to our review objective.

Included studies

Nine retrospective NRS met the inclusion criteria. In order to determine the study type and distinguish between case series and cohort studies, we applied the criteria recently proposed by Dekkers et al (Dekkers 2012). According to their proposal a cohort study is defined by the following main features:

- sampling is based on exposure;

- the occurrence of outcomes is assessed during a specified follow-up period;

- exposure can be a risk factor, a disease, or an intervention;

- absolute risk (or rate) calculation is possible;

- if a comparison group is included, relative risk can be calculated.

All included studies showed these features and were consequently classified as cohort studies.

For more details on the included studies, see Characteristics of included studies.

Excluded studies

No trials were eligible for inclusion in this section. See: Characteristics of excluded studies.

Risk of bias in included studies

Reeves et al. hypothesized that the risk of bias in NRS depends on the specific study features rather than on the design labels (such as cohort or case-control study) (Reeves 2011). Thus, we attempted to assess the study features that have a major impact on the risk of bias using the Newcastle-Ottawa Scale (NOS) for cohort studies. See Figure 2; Figure 3; Table 1. Furthermore, we analyzed risk of bias in the usual domains:

Selection bias

In NRS, groups are unlikely to be comparable due to the lack of concealed randomization within the allocation process. Consequently, NRS are more susceptible to selection bias as compared to RCTs, which is regarded as the main difference between RCTs and NRS (Reeves 2011). With regard to selection bias, we checked the representativeness of the intervention cohort (lateral pararectal stoma placement) and the comparability of the intervention (lateral pararectal) and control (transrectal) cohorts. The majority of the included studies were at unclear risk of selection bias since the authors did not sufficiently describe the derivation of the intervention cohort and whether the intervention and control cohorts were drawn from the same community.

Performance bias

We considered the risk of performance bias to be relatively low in the included studies because the surgical procedure (lateral pararectal versus transrectal stoma placement) was ascertained reliably either by reviewing secure records, such as operative reports and patient charts, or by CT or clinical examination, or both. In two radiological studies the position of the stoma in relation to the rectus abdominis muscle was assessed by CT scanning (Cingi 2006; Williams 1990). In another study the intervention was reassessed by CT examination if it remained unclear after clinical evaluation (Ortiz 1994). In one study the stomal site in relation to the rectus muscle was determined by clinical examination, through a surgeon and a staff nurse at the stoma therapy service (Sjodahl 1988). In the remaining studies the intervention must have been ascertained by chart review (though this was not always explicitly stated) (Eldrup 1982; Pilgrim 2010; von Smitten 1986) or review of a standard operative 'pro forma' (Leong 1994; Londono-Schimmer 1994).

Detection bias

Similarly, risk of detection bias was estimated to be low in most of the included studies as the outcome (parastomal herniation) was assessed either by clinical examination or CT scanning, or both, or by reviewing reliable patient records. In three studies, the outcome was assessed by physical examination and CT scanning (Cingi 2006; Ortiz 1994; Williams 1990). In two Scandinavian studies from the 1980s, parastomal herniation was assessed only by clinical examination (Sjodahl 1988; von Smitten 1986). In the most current included study, the outcome was ascertained by physical examination including "digital examination through the stomal opening" "by enterostomal nurse specialists" (Pilgrim 2010). In both studies from St. Mark's Hospital in London, UK, the outcomes (parastomal herniation and stomal prolapse) were assessed by reviewing standard operative pro formas (Leong 1994; Londono-Schimmer 1994). In the oldest of the included studies, a Danish study including patients from two Copenhagen county hospitals, all eligible living patients were screened for parastomal hernia by physical examination, whereas all eligible dead patients were assessed for the outcome by chart review (Eldrup 1982).

Incomplete outcome data

All included studies were at high risk of presenting incomplete outcome data (attrition bias). Applying the NOS, we identified that five of the nine included studies showed follow-up rates < 80% (Cingi 2006; Eldrup 1982; Leong 1994; Londono-Schimmer 1994; Williams 1990). The remaining three studies either did not present any numbers of the patients examined for eligibility or lost to follow-up (Ortiz 1994; Pilgrim 2010; Sjodahl 1988), or the numbers given seemed unreliable from a clinician's standpoint (von Smitten 1986).

Selective outcome reporting bias

The common lack of the use of a study protocol in NRS leads to a higher risk of potential selective outcome reporting bias for NRS as compared to RCTs (Reeves 2011). Features of RCTs to prevent reporting bias (for example a pre-specified protocol, ethical approval including progress and final reports, and the CONSORT statement) were missing in all included studies. Comparing the information given in the methods and results sections regarding outcomes to be assessed and the outcomes assessed, we did not discover any discrepancies. Hence, we concluded that the likelihood of selective outcome reporting remained unclear.

Other potential sources of bias

One study was supported by a grant, but no further information was provided (Ortiz 1994). This could potentially introduce additional bias.

Effects of interventions

See: Summary of findings for the main comparison Lateral pararectal versus transrectal enterostomy placement for parastomal herniation (prevention)

All included studies reported results for the primary outcome (parastomal herniation), and one study also reported data on one of the secondary outcomes (stomal prolapse) (Leong 1994). None of the included studies compared the two interventions with regard to other secondary outcomes.

There was neither a significant difference in terms of the risk for parastomal herniation (RR 1.29; 95% CI 0.79 to 2.1) (Analysis 1.1) nor with regard to the occurrence of stomal prolapse (RR 1.23; 95% CI 0.39 to 3.85) (Analysis 1.2). An I² value of 65% indicated substantial statistical heterogeneity in the meta-analysis (Analysis 1.1). The I² statistic describes the percentage of total variation across studies that is caused by heterogeneity rather than by chance (Higgins 2011). Both P values (0.31 and 0.73, respectively) were interpreted as a finding of uncertainty. The confidence intervals were very wide in both analyses. In Analysis 1.1, this could be the result of the small number of studies combined in the meta-analysis as well as the substantial heterogeneity. The wide confidence interval in Analysis 1.2 was likely to be caused by the small sample size of the only included study.

In summary, there was inconclusive evidence of a preventive effect of the compared interventions with regard to parastomal herniation.

Discussion

Parastomal herniation is one of the most common stoma complications and causes significant stoma-related morbidity, especially in patients with permanent enterostomies, for example patients with low rectal cancer who had to undergo abdomino-perineal resection. The patient relevance of this complication is high because parastomal herniation often results in further morbidity, such as skin irritation and maceration due to leakage. Moreover, it can even necessitate emergency surgery for strangulated bowel. A recent retrospective study from France, which included 782 stoma patients, showed that after a mean follow-up of 10.5 years the prevalence of parastomal herniation was 25.6% (n = 202). Of the 202 patients with parastomal hernia, more than one third (35%) complained of pain and almost one third (28%) suffered from leakage due to difficulties in fitting the stomal appliance. More than half of the patients (n = 114) underwent operative repair, but again in half of these patients (n = 57) parastomal herniation recurred within six months (Ripoche 2011). The high recurrence and morbidity rates after hernia repair make the situation of the affected patients even more precarious and underline the need for effective preventive measures.

With regard to the etiology of parastomal herniation, one has to differentiate between patient-related and surgical or technical risk factors for parastomal herniation. Ripoche et al. studied several patient-related potential risk factors such as age, gender, past medical history (ventral hernia, diabetes, corticosteroid therapy), and diagnosed condition requiring stoma formation (for example malignancy, inflammatory bowel disease, diverticulosis). The only patient factor which was significantly associated with parastomal herniation in a multivariate analysis was age > 60 years at the time of stoma placement (Ripoche 2011), which is supported by data from other studies investigating long term hernia rate and risk factors (Hong 2013; Mylonakis 2001; Pilgrim 2010). The influence of operative factors is also much debated. Trephine size, closure of the lateral space, stomal fixation to the fascia, intra- versus extraperitoneal route, and location in relation to the rectus abdominis muscle may have an influence on the occurrence of parastomal herniation (Carne 2003; Hotouras 2013). Furthermore, type of enterostomy (ileostomy versus colostomy, end versus loop ostomy), operative setting (emergency versus elective surgery), and whether a stoma therapist marked the site of the stoma preoperatively seem to have an impact on the risk of parastomal herniation.

Regardless of the fact that there was no evidence from randomized trials, the surgical dogma has emerged that a stoma should be placed through the rectus abdominis rather than lateral to the muscle in order to prevent parastomal herniation. This credo has been persistently repeated in the surgical literature, usually without any scientific evidence (Park 1999; Pearl 1985). But how could this surgical dictum arise? And why does it still persist despite the lack of evidence? In the mid 1930s Gabriel and Lloyd-Davies recommended transrectal colostomy formation for prevention of parastomal herniation (Gabriel 1935), which was approved by Turnbull 20 years later (Turnbull 1958). In the mid 1970s a study from St. Mark's Hospital in London, UK, was published reporting data on 227 patients undergoing surgery for rectal adenocarcinoma. In 35 of the included patients the colostomy was created transrectally and, after a follow-up of one to six years, six of the 35 patients were diagnosed with a parastomal hernia (Marks 1975). Thus, on the basis of their data, the authors concluded that the transrectal route cannot generally be recommended. One explanation why surgeons continued to adhere to the thesis that the stomata should be placed transrectally could be the assumption that pulling the stoma through the rectus abdominis muscle provides a more snug fit since the muscle contracts around the stomal aperture. On the other hand, the same thinking could lead to the concern that there is a higher risk of stoma-related stenosis and ileus due to tight muscle contractions around the enterostomy.

Recently, Stephenson described a novel approach to stoma formation, the lateral rectus abdominis positioned stoma (LRAPS) (Stephenson 2010), being convinced that preservation of the rectus abdominis muscle and its sheath could prevent parastomal herniation. The new technique implies that the anterior and posterior rectus sheath are only divided horizontally (not vertically) and that the rectus muscle is not incised but separated from its sheath by sharp and blunt dissection and is then retracted medially. After the bowel is delivered, any defect of the medial margins of the incisions in the anterior and posterior sheath is closed with interrupted absorbable sutures. Stephenson presented data from 29 consecutive, unselected patients who received a LRAPS. After a mean follow-up of 13 (range 7 to 18) months no parastomal hernia had been detected. In 2011 Evans published a further follow-up of the LRAPS (Evans 2011); at one year of follow-up the authors observed parastomal hernias in 5% of their patients with a LRAPS (3/62), and, at two years, the parastomal hernia rate had increased to 10% (4/41). Although the follow-up duration was still rather short, the reported parastomal herniation rates are lower than what is usually reported in the literature (Israelsson 2008; Robertson 2005).

Another emerging surgical trend is the use of prophylactic mesh for prevention of parastomal herniation. Recently, two systematic reviews of three randomized trials that included 129 patients were conducted (Shabbir 2012; Wijeyekoon 2010). Meta-analysis showed that mesh reinforcement of stomas was associated with a decreased incidence of parastomal herniation (RR 0.23; 95% CI 0.06 to 0.81; P = 0.02) as well as with a reduced proportion of patients with parastomal hernias requiring surgical repair (Wijeyekoon 2010). Though the results of these three small RCTs (Hammond 2008; Janes 2004; Janes 2009; Serra-Aracil 2009) showed a beneficial effect of mesh reinforcement with regard to prevention of parastomal herniation, with no excess morbidity, scepticism regarding the safety of placing prosthetic mesh adjacent to open bowel still seems justified. Furthermore, the overall follow-up period was relatively short (range 12 to 57 months). Hence, it remains unclear if the preventive treatment effect of prophylactic parastomal mesh reinforcement persists and is safe enough in the long term. In addition, the review authors concluded that there is a lack of evidence with regard to the preferable type of mesh and the optimal site for mesh placement; and that the role of prophylactic mesh in the emergency surgery setting is still obscure. In summary, further evidence from (multicenter) randomized trials is needed to clarify the role of prophylactic mesh placement for prevention of parastomal hernia.

On the premise that surgical prevention of parastomal herniation without the use of mesh is worthy of consideration, we aimed to collect all existing evidence regarding the question whether a stoma should be placed through or lateral to the rectus abdominis muscle. The main results of our reviewing process are summarized in the Summary of main results.

In conclusion, there is only very limited evidence from a few non-randomized cohort studies with high risk of bias regarding our review question. This lack of evidence gives rise to collective uncertainty within the surgical community as to which treatment is preferable, lateral pararectal or transrectal stoma formation. Thus, we assume 'clinical equipoise', which should be the ethical basis for the initiation of randomized trials comparing lateral pararectal to transrectal stoma placement. In the light of the complete absence of evidence from randomized trials the authors of this systematic review (JH, FH, PK, SP) designed PATRASTOM, a single-center RCT investigating the review objective (Hardt 2012), which started recruiting in April 2012.

Summary of main results

Currently, there are no RCTs assessing our review objective. However, there is one ongoing single-center pilot RCT comparing lateral pararectal to transrectal stoma placement that is scheduled for completion in 2014 (Hardt 2012). Due to the lack of RCT evidence, we reviewed the existing observational studies addressing our review objective. All included studies reported our primary outcome (parastomal hernia), and one study (Leong 1994), that included 145 patients, additionally reported one of our secondary outcomes (stomal prolapse). Seven of the nine included cohort studies, with a total of 491 participants, did not find a statistically significant difference in parastomal herniation rates after lateral pararectal compared to transrectal stoma formation. In contrast, the remaining two studies (Eldrup 1982; Sjodahl 1988) found a significant reduction of parastomal herniation if the stoma was pulled out through the belly of the rectus abdominis muscle. Eldrup presented data on the prevalence of paracolostomy hernia in 140 patients who had undergone permanent end-sigmoidostomy placement, either transrectally (n = 77) or lateral to the rectus abdominis in the left iliac fossa (n = 63) (Eldrup 1982). The second study, a Swedish study including 130 patients attending the stoma therapy service at a university hospital in Linköping, showed an almost 10-fold reduced risk of parastomal herniation after transrectal stoma placement compared to lateral pararectal stoma siting (Sjodahl 1988). Pooling the data of all included studies could not provide conclusive evidence (see Effects of interventions). Reasons for the widely differing estimates of the intervention effect (that is heterogeneity) across studies could be the lack of standardization of the surgical procedure as well as the absence of a uniform definition and detection method for parastomal hernia.

Also see Summary of findings for the main comparison.

Overall completeness and applicability of evidence

Our review aimed to compare lateral pararectal to transrectal stoma placement for prevention of parastomal herniation and other complications that are important to the patient. This was only partly accomplished. All included studies reported parastomal herniation, our primary outcome, but only one of them presented data on stomal prolapse. None of them reported any other of our secondary outcomes. Furthermore, we could only conduct one of the planned subgroup analyses and none of the sensitivity analyses because the required data were not reported in the included studies. Thus, the evidence with regard to our review objective is very limited and the identified studies could not address all of the objectives of the review. Consequently, no recommendations can be formulated on the basis of such incomplete and inconclusive evidence. The studies identified are all retrospective cohort studies and at high risk of bias, especially with regard to selection bias and incomplete outcome data (attrition bias). Since the participants were not randomly assigned to the two intervention groups, the risk of selection bias is high. Moreover, it mostly remained unclear whether the individual participants were representative of the population. Hence, external validity and generalizability of the results remain unclear, which greatly restricts the applicability of the evidence identified.

Quality of the evidence

Nine retrospective cohort studies with a total of 761 participants were identified and included in this systematic review. For key methodological features and limitations of the studies please see the Characteristics of included studies. Confidence in the estimates of the treatment effect is limited in respect to risk of bias, publication bias, imprecision, inconsistency, and indirectness. All these issues are included in the GRADE system and are summarized in the Summary of findings for the main comparison. Overall risk of bias in the included observational studies is high, especially due to possible selection bias (no randomization, unclear representativeness and comparability of the two cohorts) and high risk of attrition bias. It remains unclear whether publication bias affected the estimates of treatment effect, but it cannot be excluded because observational studies reporting higher rates of parastomal herniation and other stoma-related complications might be less likely to be published than studies presenting lower complication rates. This may be a particular concern in surgery. Since the 95% confidence interval around the estimate of effect includes both no effect and appreciable benefit or appreciable harm, and because the total number of events is less than 300, we assume that there is considerable imprecision. Moreover, the quality of evidence is diminished due to inconsistency because of the widely differing estimates of the intervention effect (that is heterogeneity) across studies, for which we failed to identify a plausible explanation. However, we did not find any evidence of indirectness with respect to the target population, intervention, and outcome of interest.

Hence, the quality of evidence is downgraded by one level, from low to very low, due to high risk of bias, imprecision, and inconsistency.

In summary, the body of evidence identified does not allow a robust conclusion regarding the objectives of the review.

Potential biases in the review process

Although we followed a strict protocol consistent with the Methodological standards for the conduct of new Cochrane Intervention Reviews, Version 2.1, 8 December 2011 (MECIR) and Meta-analysis of Observational Studies in Epidemiology (MOOSE) statements (Stroup 2000), and applied a comprehensive search strategy, this review is still prone to bias. For example, publication bias cannot be excluded in our review because NRS are not consistently indexed in trial registers (Reeves 2011). Consequently, it must be taken into consideration that we may have missed completed or ongoing NRS. Moreover, we did not screen conference proceedings, which could potentially lead to further publication bias.

Agreements and disagreements with other studies or reviews

To our knowledge, this is the first systematic review addressing this particular review question. However, several narrative reviews have discussed the objective of our review (Carne 2003; Hotouras 2013; Israelsson 2008; Martin 1996; Pearl 1989).

Authors' conclusions

Implications for practice

Based on the inconclusive evidence from nine non-randomized studies with a total of 761 participants, the authors cannot draw any conclusions with regard to implications for clinical practice. Since meta-analysis did not show a significant difference between the two compared interventions regarding their potential to prevent parastomal herniation, patients and clinicians should be aware of the clinical equipoise concerning the objective of our review. However, the fact that there is no evidence of effect does not imply that there is evidence of no effect. In summary, the knowledge that there is inconclusive evidence and clinical equipoise should be kept in mind by all practicing surgeons. Finally, the review findings may query or even abolish the surgical dictum favoring the transrectal approach.

Implications for research

This review highlights the need for randomized trials to evaluate the effectiveness of the lateral pararectal versus the transrectal approach in preventing parastomal herniation and other stoma-related morbidity in people requiring enterostomy placement. Future trials should overcome the limitations of the available evidence, that are the lack of randomization and long term results. Moreover, it is essential that future RCTs focus on patient-relevant outcomes and comprehensively assess quality of life.

Acknowledgements

Thanks to:

  • Gerta Rücker, Institute of Medical Biometry and Medical Informatics of the University Medical Center Freiburg, Freiburg i. Br., Germany, for statistical advice and methodological support;

  • Lasse T. Krogsbøll, Nordic Cochrane Center, Rigshospitalet, Copenhagen, Denmark, for the translation of Eldrup 1982 and the valuable discussion on how to review observational studies;

  • the Cochrane Colorectal Cancer Group (CCCG), Copenhagen, Denmark, especially to Henning K. Andersen and Marija Barbateskovic;

  • Gerd Antes and the team at the German Cochrane Center, Freiburg i. Br., Germany.

Data and analyses

Download statistical data

Comparison 1. Lateral pararectal versus transrectal enterostomy placement
Outcome or subgroup titleNo. of studiesNo. of participantsStatistical methodEffect size
1 parastomal hernia9761Risk Ratio (M-H, Random, 95% CI)1.29 [0.79, 2.10]
2 stomal prolapse1145Risk Ratio (M-H, Random, 95% CI)1.23 [0.39, 3.85]
Analysis 1.1.

Comparison 1 Lateral pararectal versus transrectal enterostomy placement, Outcome 1 parastomal hernia.

Analysis 1.2.

Comparison 1 Lateral pararectal versus transrectal enterostomy placement, Outcome 2 stomal prolapse.

Comparison 2. Subgroup analyses - ileostomy versus colostomy
Outcome or subgroup titleNo. of studiesNo. of participantsStatistical methodEffect size
1 parastomal hernia6521Risk Ratio (M-H, Random, 95% CI)1.21 [0.73, 1.99]
1.1 ileostomy2173Risk Ratio (M-H, Random, 95% CI)0.70 [0.21, 2.29]
1.2 colostomy4348Risk Ratio (M-H, Random, 95% CI)1.44 [0.78, 2.66]
Analysis 2.1.

Comparison 2 Subgroup analyses - ileostomy versus colostomy, Outcome 1 parastomal hernia.

Appendices

Appendix 1. MEDLINE search strategy

No.Search
#1stoma [tiab] OR stomas [tiab] OR stomata [tiab] OR stomal [tiab] OR parastom* [tiab]
#2enterostom* [tiab] OR colostom* [tiab] OR cecostom* [tiab] OR duodenostom* [tiab] OR ileostom* [tiab] OR jejunostom* [tiab]
#3"anus praeter" [tiab] OR "preternatural anus" [tiab] OR "artificial anus" [tiab]
#4Surgical Stomas [mh] OR Enterostomy [mh]
#5#1 OR #2 OR #3 OR #4
#6herni* [tiab]
#7hernia [Mesh:NoExp] OR hernia, abdominal [Mesh:NoExp]
#8#6 OR #7
#9#5 AND #8
#10animals [mh] NOT humans [mh]
#11#9 NOT #10

Appendix 2. EMBASE search strategy

No.Search
#1(stoma or stomas or stomata or stomal or parastom*).tw.
#2(enterostom* or colostom* or cecostom* or duodenostom* or ileostom* or jejunostom*).tw.
#3("anus praeter" or "preternatural anus" or "artificial").tw.
#4exp enterostomy/
#51 or 2 or 3 or 4
#6herni*.tw.
#7hernia/
#8abdominal wall hernia/
#96 or 7 or 8
#105 and 9

Appendix 3. The Cochrane Library search strategy

No.Search
#1"stoma" or "stomas" or "stomata" or "stomal" or parastom*
#2enterostom* or colostom* or cecostom* or duodenostom* or ileostom* or jejunostom*
#3"anus praeter" or "preternatural anus" or "artificial anus"
#4MeSH descriptor: [Surgical Stomas] explode all trees
#5MeSH descriptor: [Enterostomy] explode all trees
#6#1 or #2 or #3 or #4 or #5
#7herni*
#8MeSH descriptor: [Hernia] this term only
#9MeSH descriptor: [Hernia, Abdominal] this term only
#10#7 or #8 or #9
#11#6 and #10

Appendix 4. Science Citation Index Expanded (Web of Science) search strategy

No.Search
#1Topic=(stoma OR stomas OR stomata OR stomal OR parastom*)
#2Topic=(enterostom* OR colostom* OR cecostom* OR duodenostom* OR ileostom* OR jejunostom*)
#3Topic=("anus praeter" OR "preternatural anus" OR "artificial anus")
#4#3 OR #2 OR #1
#5Topic=(herni*)
#6#5 AND #4

Appendix 5. LILACS search strategy

(TW:stoma OR stomas OR stomata OR stomal OR estoma OR estomas OR parastom$ OR paraestom$ OR "surgical stomas" OR "estomas quirúrgicos" OR "estomas cirúrgicos" OR "anus praeter" OR "preternatural anus" OR "artificial anus" OR "anal artificial" OR enterostom$ OR colostom$ OR cecostom$ OR duodenostom$ OR ileostom$ OR jejunostom$ OR yeyunostom$) AND (TW:herni$)

Appendix 6. ClinicalTrials.gov search strategy

No.Search
#1(stoma OR stomas OR stomata OR stomal OR parastomal OR enterostomy OR enterostomies OR colostomy OR colostomies OR cecostomy OR cecostomies) AND (hernia OR hernias OR herniae OR herniation OR herniations OR hernial OR herniated)
#2(duodenostomy OR duodenostomies OR ileostomy OR ileostomies OR jejunostomy OR jejunostomies) AND (hernia OR hernias OR herniae OR herniation OR herniations OR hernial OR herniated)
#3((anus AND praeter) OR (preternatural AND anus) OR (artificial AND anus)) AND (hernia OR hernias OR herniae OR herniation OR herniations OR hernial OR herniated)

Appendix 7. ICTRP Search Platform search strategy

No.Search
#1stoma AND herni*
#2stomas AND herni*
#3stomata AND herni*
#4stomal AND herni*
#5parastom* AND herni*
#6enterostom* AND herni*
#7colostom* AND herni*
#8cecostom* AND herni*
#9duodenostom* AND herni*
#10ileostom* AND herni*
#11jejunostom* AND herni*
#12anus praeter AND herni*
#13preternatural anus AND herni*
#14artificial anus AND herni*

Contributions of authors

Design, data extraction, analysis, interpretation, and drafting of review: JH, FH.

Design, resolution of discrepancies, interpretation, drafting, and supervision of review: JM, PK, SP.

Design and execution of search strategies, search documentation, and drafting of review: MM.

Declarations of interest

None known.

Differences between protocol and review

We undertook a broader search approach than stated in the protocol, searching for all types of non-randomized studies, because study design labels are not used consistently by authors and are thus not indexed reliably by bibliographic databases. This applies especially for non-randomized studies. We proved this by adding a specificity search filter (Fraser 2006) to our subject search in MEDLINE, which resulted in exclusion of relevant references mentioned in the protocol. Therefore, we decided to search without any restriction by publication or study type.

In order to further enhance the overall recall of the search and to minimize language bias, we searched two more databases than stated in the review protocol: Science Citation Index Expanded and LILACS.

The German Clinical Trials Register, that is mentioned in the protocol, is included in the International Clinical Trials Research Platform (ICTRP) and was thus not searched separately. Three trial registers (HKUCTR, UKCTG, and UKRNPD),which were not mentioned in our protocol, were searched since they are not included in the ICTRP.

We also concretized the inclusion criteria for studies. Studies had to compare lateral pararectal versus transrectal enterostomy placement with regard to the incidence of parastomal herniation.

Only one of the planned subgroup analyses could be conducted (see Subgroup analysis and investigation of heterogeneity and Analysis 2.1). None of the planned sensitivity analyses were conducted (see Sensitivity analysis).

Characteristics of studies

Characteristics of included studies [ordered by study ID]

Cingi 2006

MethodsA retrospective cohort study (according to the definition of a cohort study by Dekkers 2012)
Participants

46 patients operated between January 2000 and January 2005 at Marmara University Hospital in Istanbul, Turkey:

  • 23 patients with any kind of diagnosis which had been an indication for enterostomy placement

  • 23 patients who had already undergone enterostomy reversal

Interventions
  • Interventions for the 23 patients who still had an enterostomy: 6 patients underwent lateral pararectal enterostomy placement versus 14 patients received a transrectal enterostomy (in 3 patients who still had an enterostomy the position of the enterostomy in relation to the rectus abdominis muscle remained unclear since the patients refused a CT scan)

  • Interventions for the 23 patients who had already received ileostomy reversal: 7 patients had undergone lateral pararectal enterostomy placement versus 16 patients had received a transrectal enterostomy

Standardization of the surgical procedure: unclear

Outcomes

Incidence of parastomal hernia:

  • assessed by physical examination

  • assessed by CT scan

Incidence of closed ostomy site incisional hernia

  • assessed by physical examination

  • assessed by CT scan

Notes

Definitions:

  • Definition of parastomal hernia on physical examination: "a bulging during the Valsalva maneuver and palpation of the fascial defect"

  • Definition of parastomal hernia on CT scan: "a loop of intestine or any abdominal organ, as well as preperitoneal fat, protruding through the defect alongside the ostomy"

Risk of bias
BiasAuthors' judgementSupport for judgement
Representativeness of the experimental intervention cohortHigh riskNo detailed description of derivation of the cohorts. All patients who underwent any kind of enterostomy for any underlying disease from January 2000 to January 2005 at Marmara University Hospital were contacted and invited for interview, physical examination, and CT evaluation.
Selection of the control cohortUnclear riskIt seems likely that both intervention groups (lateral pararectal versus transrectal stoma placement) were drawn from the same or at least a similar community.
Ascertainment of interventionLow riskType of intervention (lateral pararectal versus transrectal stoma placement) was ascertained by CT scanning.
Demonstration that outcome of interest was not present at start of studyLow riskIn the absence of an enterostomy, parastomal herniation and other stoma-related complications could not have been present.
Comparability of cohorts on the basis of the design or analysisHigh riskNeither the experimental intervention group and the control group were matched in the design nor confounders were adjusted for in the analysis.
Assessment of outcomeLow riskOutcome (parastomal hernia) was assessed by physical examination and CT scanning.
Was follow-up long enough for outcomes to occurHigh riskMedian follow-up was only 15 (range 2-63) months, which is rather short with regard to the likelihood of occurrence of parastomal hernia.
Adequacy of follow-up of cohortsUnclear riskThe authors identified 161 eligible patients of whom 58 had already died. Of the remaining 103, only 46 accepted the invitation for interview and re-examination. 23 of the 46 included patients still had an ostomy, whereas the other half had already undergone ostomy reversal. 3 of the 23 patients with ostomy refused to undergo CT evaluation. Follow-up rate < 80%.
Reporting biasUnclear riskUnclear whether selective outcome reporting was present.
Other biasUnclear riskUnclear whether other bias was present.

Eldrup 1982

MethodsA retrospective cohort study (according to the definition of a cohort study by Dekkers 2012)
Participants140 patients with colorectal (n=131) or gynecological malignancies (n=3) or with benign colorectal disease (n=6) who were operated at two different Danish county hospitals, one hospital in Herlev and one in Gentofte, between June 1976 and July 1980.
Interventions

63 patients underwent placement of a lateral pararectal end sigmoidostomy versus 77 patients underwent placement of a transrectal end sigmoidostomy

Standardization of the surgical procedure: unclear

OutcomesIncidence of paracolostomy hernia
NotesNo definition of paracolostomy hernia
Risk of bias
BiasAuthors' judgementSupport for judgement
Representativeness of the experimental intervention cohortUnclear riskThe cohorts were derived from two Copenhagen county hospitals, one hospital in Herlev and one in Gentofte. It remains unclear whether cohorts were representative of the average, elderly, community-dwelling resident.
Selection of the control cohortLow riskIt seems likely that both intervention groups (lateral pararectal versus transrectal stoma placement) were drawn from the same or at least a similar community.
Ascertainment of interventionLow riskType of intervention was ascertained by patient record (site of the stoma depended on the hospital where it was placed: in one hospital - not mentioned if this was the one in Herlev or the one in Gentofte - only transrectal stomas were constructed, in the other one only lateral pararectal stomas).
Demonstration that outcome of interest was not present at start of studyLow riskIn the absence of an enterostomy, parastomal herniation and other stoma-related complications could not have been present.
Comparability of cohorts on the basis of the design or analysisHigh riskNeither the experimental intervention group and the control group were matched in the design nor confounders were adjusted for in the analysis.
Assessment of outcomeUnclear risk

Outcome (paracolostomy hernia) was assessed by physical examination (in the 93 patients who were still alive and agreed to re-examination) or patient records were screened for the occurrence of paracolostomy hernia if patients had died (47 patients). Risk of detection bias remains unclear in the 47 cases where patients had already died since the following source of bias cannot be excluded:

It is unclear how much attention was paid during follow-up clinic visits to presence or absence of parastomal herniation, and it is also unclear whether this was checked at all during routine follow-up visits if there was no standard pro forma or standardized check list for clinic follow-up visits. Even if patients were examined for parastomal herniation, it is possible that examination findings were not recorded since they were not routinely assessed.

Was follow-up long enough for outcomes to occurHigh riskOnly 143 of 261 patients, who had received a permanent end sigmoidostomy during the 4-year inclusion period, had a minimum follow-up of 6 months, which was one of the inclusion criteria of the study (follow-up rate < 80%). 3 of the 96 eligible patients who were still alive were not assessed for parastomal herniation by clinical re-examination. Reasons for the 3 dropouts are not stated.
Adequacy of follow-up of cohortsUnclear riskSee above.
Reporting biasUnclear riskUnclear whether selective outcome reporting was present.
Other biasUnclear riskUnclear whether other bias was present.

Leong 1994

MethodsA retrospective cohort study (according to the definition of a cohort study by Dekkers 2012)
Participants150 patients operated at St Mark's Hospital in London, UK, during the decade January 1971 to December 1980 for the following underlying disease: ulcerative colitis (n=71), ulcerative colitis and carcinoma (n=13), Crohn’s colitis (n=59), indeterminate colitis (n=5), familial adenomatous polyposis (FAP) with malignant change (n=2)
Interventions

Proctocolectomy (n=82) or colectomy (n=68) with placement of lateral pararectal (n=42) versus transrectal (n=103) permanent end ileostomy (site of stoma unclear in 5 patients)

Standardization of the surgical procedure: unclear

Outcomes
  • Incidence of paraileostomy hernia

  • Incidence of stomal prolapse

  • Other stomal complications: necrosis, retraction, peristomal suppuration and fistulation (no comparison drawn between lateral pararectal and transrectal stoma)

NotesAll presented data on participants, interventions, and outcomes were extracted from a "standard pro forma" which was used for all patients undergoing surgery for inflammatory bowel disease at the hospital where the study was conducted.
Risk of bias
BiasAuthors' judgementSupport for judgement
Representativeness of the experimental intervention cohortUnclear riskAll patients had undergone (procto)colectomy with ileostomy placement for inflammatory bowel disease between 1971 and 1980 at the same hospital in London, UK. Consequently, one could deduce that both intervention groups (lateral pararectal versus transrectal ileostomy) were drawn from the same or at least a similar community.
Selection of the control cohortLow riskSee above.
Ascertainment of interventionLow riskType of intervention (lateral pararectal versus transrectal stoma placement) was ascertained by chart review: "A standard pro forma is used at St. Mark's for patients undergoing surgery for inflammatory bowel disease. From this were extracted the following details: (...) and siting of the stoma with regard to abdominal wall musculature (through or lateral to the rectus abdominis)."
Demonstration that outcome of interest was not present at start of studyLow riskIn the absence of an enterostomy, parastomal herniation and other stoma-related complications could not have been present.
Comparability of cohorts on the basis of the design or analysisHigh riskNeither the experimental intervention group and the control group were matched in the design nor confounders were adjusted for in the analysis.
Assessment of outcomeLow riskOutcomes (para-ileostomy hernia, prolapse, and other stomal complications) were assessed by chart review: "A standard pro forma is used at St. Mark's for patients undergoing surgery for inflammatory bowel disease. From this were extracted the following details: (...). Stomal complications evaluated were: (...); prolapse; (...); parastomal herniation; (...)".
Was follow-up long enough for outcomes to occurLow riskMean duration of follow-up was 9.2 (range 0.3 - 20.0) years.
Adequacy of follow-up of cohortsUnclear riskThe authors do not state how many patients were potentially eligible or examined for eligibility. There is also no information on patients lost to follow-up or dropouts. The authors only state that reasons for termination of follow-up were return to residence abroad, inability to travel due to poor health, and death. 150 patients were included in the analysis. It seems likely that follow-up rate was < 80%. All patients were operated 14 to 23 years before the study was published.
Reporting biasUnclear riskUnclear whether selective outcome reporting was present.
Other biasUnclear riskUnclear whether other bias was present.

Londono-Schimmer 1994

MethodsA retrospective cohort study (according to the definition of a cohort study by Dekkers 2012)
Participants203 patients operated at St Mark's Hospital in London, UK, during the decade January 1971 to December 1980: 184 patients with rectal cancer, 14 patients with squamous cell anal cancer, 1 patient with rectal leiomyosarcoma, 4 patients who had to undergo Hartmann’s procedure (diagnoses not stated)
Interventions

Abdomino-perineal resection (n=199) or Hartmann's procedure (n=4) with placement of a lateral pararectal (n=31) versus transrectal (n=72) end sigmoid colostomy

Standardization of the surgical procedure: unclear

Outcomes
  • Incidence of para-colostomy hernia

  • Other stomal complications: stenosis, prolapse, obstruction, retraction, skin complications (no comparison drawn between lateral pararectal and transrectal stoma)

Notes
  • The site of the colostomy in relation to the rectus abdominis muscle was known in only 103 of the patients

  • All presented data on participants, interventions, and outcomes were extracted from a standard operative proforma which was used for all patients undergoing surgery for anorectal malignancy at the hospital where the study was conducted

Risk of bias
BiasAuthors' judgementSupport for judgement
Representativeness of the experimental intervention cohortUnclear riskAll patients had undergone abdomino-perineal resection or Hartmann's procedure with sigmoidostomy placement between 1971 and 1980 at the same hospital in London, UK. The majority of patients suffered from colorectal cancer. Consequently, one could deduce that both intervention groups (lateral pararectal versus transrectal sigmoidostomy) were drawn from the same or at least a similar community.
Selection of the control cohortLow riskSee above.
Ascertainment of interventionLow riskType of intervention (lateral pararectal versus transrectal stoma placement) was ascertained by chart review: "There is a standard operative proforma at St. Mark's for patients undergoing surgery for colorectal cancer. From this proforma, the following details were extracted: (...) and the siting of the stoma with regard to abdominal wall musculature (through or lateral to the rectus abdominis)."
Demonstration that outcome of interest was not present at start of studyLow riskIn the absence of an enterostomy, parastomal herniation and other stoma-related complications could not have been present.
Comparability of cohorts on the basis of the design or analysisHigh riskNeither the experimental intervention group and the control group were matched in the design nor confounders were adjusted for in the analysis.
Assessment of outcomeLow riskOutcomes (para-colostomy hernia, other stomal complications) were assessed by chart review: "There is a standard operative proforma at St. Mark's for patients undergoing surgery for colorectal cancer. From this proforma, the following details were extracted: (...). The stomal complications evaluated were (...), parastomal herniation, (...)".
Was follow-up long enough for outcomes to occurLow riskPatients were followed up for at least 13 years after the intervention.
Adequacy of follow-up of cohortsUnclear risk289 patients had received a permanent end colostomy during the decade from 1971 to 1980 and were thus examined for eligibility. 203 of these patients were confirmed eligible. Reasons for exclusion in the remaining 86 patients were: 5 died early in the postoperative period, 11 were followed up at other hospitals, 27 lived abroad, 36 had no follow-up recorded, and in 7 cases files could not be found. Hence, the follow-up rate is about 70%. But in only 103 of 203 included patients the exact siting of the stoma with regard to the rectus abdominis muscle was known to the authors.
Reporting biasUnclear riskUnclear whether selective outcome reporting was present.
Other biasUnclear riskUnclear whether other bias was present.

Ortiz 1994

MethodsA retrospective cohort study (according to the definition of a cohort study by Dekkers 2012)
Participants54 patients with rectal cancer operated at Virgen del Camino Hospital, Pamplona, Spain
Interventions

Abdomino-perineal resection with placement of a lateral pararectal (n=29) versus transrectal (n=25) colostomy

Standardization of the surgical procedure: unclear

OutcomesIncidence of paracolostomy hernia (assessed by clinical examination and if unclear by CT scan)
Notes
  • The study was supported by a grant FIss-90/0725

  • The location of the colostomy in relation to the rectus abdominis muscle was assessed by clinical examination and, if unclear, by CT scan

  • Definition of para-colostomy hernia: "A para-colostomy hernia was defined as one which appears around the colostomy, either partially or totally surrounding it. Hernias through the laparotomy scar near to colostomy were excluded because it is impossible to determine the exact origin of the hernia in these cases."

Risk of bias
BiasAuthors' judgementSupport for judgement
Representativeness of the experimental intervention cohortUnclear riskAll patients had undergone abdomino-perineal excision with colostomy for rectal cancer at the same hospital in Pamplona, Spain, five years before the study was conducted. The authors state that all operations were performed by the same team of surgeons. Consequently, one could deduce that both intervention groups (lateral pararectal versus transrectal sigmoidostomy) were drawn from the same or at least a similar community.
Selection of the control cohortLow riskSee above.
Ascertainment of interventionLow riskType of intervention (lateral pararectal versus transrectal stoma placement) was determined by clinical examination (n=45) or if still doubtful by CT scanning (n=9).
Demonstration that outcome of interest was not present at start of studyLow riskIn the absence of an enterostomy, parastomal herniation and other stoma-related complications could not have been present.
Comparability of cohorts on the basis of the design or analysisHigh riskNeither the experimental intervention group and the control group were matched in the design nor confounders were adjusted for in the analysis.
Assessment of outcomeLow riskOutcome (parastomal hernia) was determined by clinical examination. 9 patients also underwent CT scanning because the anatomical position of the stoma still remained in doubt after physical examination.
Was follow-up long enough for outcomes to occurLow riskThe authors only state that they included "54 consecutive patients who had previously undergone an abdominoperineal excision for rectal cancer five years before" (follow up = 5 years). There are no data reported with regard to the number of patients who had been examined for eligibility. Additionally, it is not stated how many patients had been lost to follow-up.
Adequacy of follow-up of cohortsUnclear riskSee above.
Reporting biasUnclear riskUnclear whether selective outcome reporting was present.
Other biasUnclear riskThe study was supported by a grant FIss-90/0725, but no further information is provided. This could be a potential source of bias.

Pilgrim 2010

MethodsA retrospective cohort study (according to the definition of a cohort study by Dekkers 2012)
Participants90 "unselected consecutive patients attending routine outpatient clinic visits" at Alfred Hospital, Melbourne, Australia, between August 2004 and July 2006 with the following underlying diseases: cancer (n=40), inflammatory bowel disease (n=26), 4 patients requiring urinary diversion, diverticular disease (n=6), anastomotic breakdown (n=2), slow transit constipation (n=2), bowel ischemia (n=4), fecal incontinence (n=2), perianal sepsis (n=2), bowel perforation (n=2)
Interventions

Lateral pararectal (n=10) versus transrectal (n=80) stoma placement

Types of surgical procedures not reported. All patients underwent stoma formation and the following types of ostomies were created: 37 sigmoidostomies, 6 transversostomies, 41 ileostomies (of which 24 were loop ileostomies), 5 ileal conduits, 1 cecostomy

Standardization of the surgical procedure: unclear

OutcomesPrevalence of parastomal hernia (assessed by physical examination including digital examination through the stomal opening)
Notes
  • Definition of parastomal hernia: "a protrusion of abdominal contents through a widened trephine opening in close relation to the stomal loop (as opposed to subcutaneous prolapse or other stomal bulging), but it was not defined further in terms of subtype"

  • Grading of the parastomal hernia size: "Hernias were graded small, moderate, or large. Hernias more than twice the size of the stoma were considered large, hernias up to twice the size of the stoma were considered moderate, and hernias apparent on palpation but not obviously visible were considered small."

Risk of bias
BiasAuthors' judgementSupport for judgement
Representativeness of the experimental intervention cohortUnclear riskAll patients attended the outpatient stomal therapy service at the same hospital in Melbourne, Australia, during the two-year study inclusion period from August 2004 until July 2006. Underlying diseases and surgical therapies varied, but the majority of patients required stoma surgery due to cancer (n=40) or inflammatory bowel disease (n=26). It remains unclear whether both intervention groups (lateral pararectal versus transrectal stoma placement) were drawn from the same or at least a similar community.
Selection of the control cohortUnclear riskSee above.
Ascertainment of interventionLow riskThough it is not stated explicitly, one must assume that the type of intervention was ascertained by operative report and/or patient chart.
Demonstration that outcome of interest was not present at start of studyLow riskIn the absence of an enterostomy, parastomal herniation and other stoma-related complications could not have been present.
Comparability of cohorts on the basis of the design or analysisHigh riskNeither the experimental intervention group and the control group were matched in the design nor confounders were adjusted for in the analysis.
Assessment of outcomeLow riskOutcome (parastomal hernia) was ascertained by physical examination including "digital examination through the stomal opening" "by enterostomal nurse specialists".
Was follow-up long enough for outcomes to occurHigh riskMedian length of follow-up was 14.1 months. Follow-up rates cannot be calculated.
Adequacy of follow-up of cohortsUnclear riskThe authors only state that they "prospectively audited" 90 "unselected consecutive patients attending routine outpatient clinic visits".
Reporting biasUnclear riskUnclear whether selective outcome reporting was present.
Other biasUnclear riskUnclear whether other bias was present.

Sjodahl 1988

MethodsA retrospective cohort study (according to the definition of a cohort study by Dekkers 2012)
Participants130 patients attending the stoma therapy service at the university hospital in Linköping, Sweden, with the following underlying diseases: rectal cancer (n=54), ulcerative colitis (n=28), Crohn’s disease (n=22), fecal incontinence (n=14), gynecological disease (n=6), diverticulitis (n=3), colon cancer (n=1), anal cancer (n=1), pseudo-obstruction (n=1)
Interventions

Placement of a lateral pararectal (n=23) versus a transrectal (n=107) enterostomy (79 sigmoidostomies, 45 end ileostomies, 3 loop ileostomies, 2 end transversostomies, 1 loop transversostomy)

Standardization of the surgical procedure: unclear

OutcomesPrevalence of parastomal hernia (assessed by physical examination by a surgeon and a staff nurse at the stoma therapy service)
NotesDefinition of parastomal hernia on physical examination ("the patient was examined in both supine and standing position"): "a bulge restricted to that area and caused by protrusion of abdominal contents. Subcutaneous prolapse or general muscular weakness with bulging of the lower part of the abdomen were thus excluded from the definition".
Risk of bias
BiasAuthors' judgementSupport for judgement
Representativeness of the experimental intervention cohortUnclear riskAll included patients were attending the stoma therapy service at the Swedish university hospital where the study was conducted. Underlying diseases and indications for stoma placement varied widely, but the majority of patients suffered either from rectal cancer (54/130) or from inflammatory bowel disease (50/130). There is no information on socio-economic or educational background of the participants. Nonetheless, it seems likely that both intervention groups (lateral pararectal versus transrectal stoma placement) were drawn from the same or at least a similar community.
Selection of the control cohortLow riskSee above.
Ascertainment of interventionLow riskType of intervention (lateral pararectal versus transrectal stoma placement) was determined by clinical examination "performed by the surgeon and staff nurse at the stomatherapy service".
Demonstration that outcome of interest was not present at start of studyLow riskIn the absence of an enterostomy, parastomal herniation and other stoma-related complications could not have been present.
Comparability of cohorts on the basis of the design or analysisHigh riskNeither the experimental intervention group and the control group were matched in the design nor confounders were adjusted for in the analysis.
Assessment of outcomeLow riskOutcome (parastomal hernia) was ascertained by clinical examination "performed by the surgeon and staff nurse at the stomatherapy service". A clear definition of parastomal hernia was given.
Was follow-up long enough for outcomes to occurUnclear riskMean follow up was 84±80.4 months (+/-S.D.); range 12-432 months (1-36 years).
Adequacy of follow-up of cohortsUnclear riskThe authors state that they included "65 men and 65 women attending the stomatherapy service" at the hospital where the study was conducted. There are no data reported with regard to the number of patients who had been examined for eligibility or the number lost to follow-up. The authors only explain that they excluded patients "whose general health was too poor to permit attendance at the clinic, e.g. with end-stage cancer or senility". Again, no number is given.
Reporting biasUnclear riskUnclear whether selective outcome reporting was present.
Other biasUnclear riskUnclear whether other bias was present.

von Smitten 1986

MethodsA retrospective cohort study (according to the definition of a cohort study by Dekkers 2012)
Participants54 patients with rectal carcinoma (n=50), anal carcinoma (n=3), or anorectal melanoma (n=1) operated at Helsinki University Central Hospital, Helsinki, Finland, between 1973 and 1980
Interventions

Abdominoperineal excision (n=53) or Hartmann's procedure (n=1) with placement of a lateral pararectal (n=26) versus transrectal (n=25) end sigmoidostomy (for 3 patients the stomal site in relation to the rectus abdominis muscle is not reported)

Standardization of the surgical procedure: unclear

Outcomes

Late complications of end sigmoidostomy (assessed by interviewing the patient and clinical examination):

  • Paracolostomy hernia

  • other complications: stomal stenosis, inappropriate stoma site, retraction of stoma, peristomal eczema

NotesParastomal hernias with a diameter ≥10 cm were classified as large
Risk of bias
BiasAuthors' judgementSupport for judgement
Representativeness of the experimental intervention cohortUnclear riskAll included patients underwent surgery for anorectal malignancies at the Finnish university hospital where the study was conducted. The authors claim that there were only 58 patients who received a permanent end sigmoidostomy in the management of anorectal malignancy within a time period of 7 years. Considering the fact that this number is very small for such a time period in combination with the setting of a university hospital, one could assume that selection bias probably occurred. There is no information on socio-economic or educational background of the participants. Hence, it remains unclear whether the included patients were somewhat representative of the average, elderly, community-dwelling resident. Nonetheless, it seems likely that both intervention groups (lateral pararectal vs. transrectal stoma placement) were drawn from the same or at least a similar community.
Selection of the control cohortLow riskSee above.
Ascertainment of interventionLow riskThough it is not stated explicitly, one must assume that the type of intervention was ascertained by the operative report and/or patient chart.
Demonstration that outcome of interest was not present at start of studyLow riskIn the absence of an enterostomy, parastomal herniation and other stoma-related complications could not have been present.
Comparability of cohorts on the basis of the design or analysisHigh riskNeither the experimental intervention group and the control group were matched in the design nor confounders were adjusted for in the analysis.
Assessment of outcomeLow riskOutcome (parastomal hernia) was ascertained by interviewing the patient and clinical examination.
Was follow-up long enough for outcomes to occurUnclear riskLength of follow up ranged from 12-96 months.
Adequacy of follow-up of cohortsUnclear riskNo data presented on how many patients were examined for eligibility. The authors claim that there were only 58 patients who received a permanent end sigmoidostomy in the management of anorectal malignancy within a time period of 7 years. 54 of these patients could be included in the analysis. It is not stated why the remaining 4 patients were excluded. Since it is likely that important data are missing, no reliable follow-up rates can be calculated.
Reporting biasUnclear riskUnclear whether selective outcome reporting was present.
Other biasUnclear riskUnclear whether other bias was present.

Williams 1990

MethodsA retrospective cohort study (according to the definition of a cohort study by Dekkers 2012)
Participants46 patients with inflammatory bowel disease (13 with Crohn's disease, 33 with ulcerative colitis) operated at the Department of Surgery, University of Wales College of Medicine, Heath Park, Cardiff, UK, between 1972 and 1987
Interventions

16 patients underwent colectomy with placement of a lateral pararectal end ileostomy versus 12 patients underwent colectomy with placement of a transrectal end ileostomy (only 28/46 patients agreed to undergo CT scanning; for the remaining patients the stomal site in relation to the rectus abdominis muscle could not be assessed by CT scan and is thus not reported).

Standardization of the surgical procedure: unclear

Outcomes
  • Incidence of para-ileostomy hernia (assessed by clinical examination (n=46) and if patients agreed by CT scan (n=28))

  • Ability of CT to detect paraileostomy hernia

Notes

Definitions:

  • Definition of para-ileostomy hernia on physical examination ("with the patient supine and erect after removal of the stoma appliance"): "palpable cough impulse in the para-ileostomy region"

  • Definition of para-ileostomy hernia on CT scan: "if an extra loop of bowel was visible outside the abdominal cavity"

All CT scans were reviewed independently by two radiologists.

Risk of bias
BiasAuthors' judgementSupport for judgement
Representativeness of the experimental intervention cohortUnclear riskAll patients had undergone colectomy with ileostomy placement for inflammatory bowel disease under the care of one surgeon between 1972 and 1987. The authors claim that there were only 60 eligible patients within a time period of 15 years. Considering the fact that this number is very small for such a time period in combination with the setting of a university hospital, one could assume that selection bias probably occurred. There is no information on socio-economic or educational background of the participants. Hence, it remains unclear whether the included patients were somewhat representative of the average, elderly, community-dwelling resident. Nonetheless, one could deduce that both intervention groups (lateral pararectal versus transrectal ileostomy) were drawn from the same or at least a similar community.
Selection of the control cohortLow riskSee above.
Ascertainment of interventionLow riskType of intervention (lateral pararectal versus transrectal stoma placement) was ascertained by CT scanning.
Demonstration that outcome of interest was not present at start of studyLow riskIn the absence of an enterostomy, parastomal herniation and other stoma-related complications could not have been present.
Comparability of cohorts on the basis of the design or analysisHigh riskNeither the experimental intervention group and the control group were matched in the design nor confounders were adjusted for in the analysis.
Assessment of outcomeLow riskOutcome (para-ileostomy hernia) was assessed by physical examination and CT scanning. The CT scans were reviewed independently by two radiologists.
Was follow-up long enough for outcomes to occurLow riskMedian length of follow-up was 78 months (6.5 years).
Adequacy of follow-up of cohortsUnclear risk

The authors claim that there were only 60 potentially eligible patients. After examination for eligibility, there were only 46 patients available for review. The remaining 14 had either died (n=7), were lost to follow-up (n=5; reasons not stated) or had undergone ileorectal anastomosis (n=2).

Only 28 of the 46 patients agreed to be assessed for para-ileostomy hernia by CT scanning. Rates for clinical and radiological (CT scan) follow-up were 77% and 47%, respectively.

Reporting biasUnclear riskUnclear whether selective outcome reporting was present.
Other biasUnclear riskUnclear whether other bias was present.

Characteristics of excluded studies [ordered by study ID]

StudyReason for exclusion
Caricato 2007No information on stomal site in relation to the rectus abdominis muscle. Follow-up was rather short with a mean follow-up of 4 months (range: 3–23).
Carlstedt 1987Only transrectal stomas. Parastomal hernia not defined as an outcome measure, thus not assessed. Aim of the study was to investigate the need for surgical ileostomy revision.
Green 1966No information on stomal site in relation to the rectus abdominis muscle. Parastomal hernia not defined as an outcome measure, thus not assessed.
Hallböök 2002No information on stomal site in relation to the rectus abdominis muscle. Parastomal hernia not defined as an outcome measure, thus not assessed.
Hoffman 1992No information on stomal site in relation to the rectus abdominis muscle.
Leenen 1989Only transrectal stomas. No comparison drawn (not even with a historical control or data from literature) between transrectal and lateral pararectal stoma placement.
Miles 1983No information on stomal site in relation to the rectus abdominis muscle.
Park 1999No information on stomal site in relation to the rectus abdominis muscle in the Methods and Results sections. In the Discussion, the authors state that, at their hospital, it is taught to place all stomas through the rectus abdominis muscle claiming that this bears a lower risk for parastomal herniation as compared to lateral pararectal stoma siting.
Pearl 1985No information on stomal site in relation to the rectus abdominis muscle. In the Discussion section, the authors recommend to place all stomas through the rectus abdominis muscle without providing any data to support this recommendation.
Stephenson 2010Only lateral pararectal enterostomies. There is no internal transrectal control group. Though the authors of this prospective uncontrolled cohort study provide detailed information on the technique for lateral pararectal stoma formation as well as valuable data on the incidence of parastomal herniation after lateral pararectal stoma placement at a follow-up of up to two years, we decided to exclude the study because of the absence of a control arm.
Zanolla 1979The study compares complications of median (the stoma is pulled through the median explorative wound) versus lateral colostomy. No information on stomal site in relation to the rectus abdominis muscle.

Characteristics of ongoing studies [ordered by study ID]

Hardt 2012

  1. a

    Information given in this table according to http://apps.who.int/trialsearch/ and https://drks-neu.uniklinik-freiburg.de/drks_web/, respectively. The WHO International Clinical Trials Registry Platform including the German Clinical Trials Register (DRKS) was searched in October 2012.

Trial name or titlePATRASTOM: a randomized, open label, mono-center surgical pilot trial with two parallel study groups to investigate the feasibility of a randomized trial in this patient population as well as differences in parastomal hernia rate and/or other stoma-related complications
Methodsa randomized, open label, mono-center surgical pilot trial with two parallel study groups
Participants

Patients necessitating a temporary loop ileostomy

Key inclusion criteria:

  • patient (age >18 years) with indication for elective temporary loop ileostomy, e.g. patient with rectal cancer undergoing elective low anterior resection with placement of a temporary, protective loop ileostomy

  • written informed consent

Key exclusion criteria:

  • emergency operations

  • ostomies not definitely planned to be reversed/permanent ostomies

  • age <18 years

InterventionsLateral pararectal versus transrectal (control intervention) enterostomy placement
Outcomes

Primary endpoint is the incidence of parastomal hernias defined by any of the following events:

i) clinically manifest parastomal hernia as any palpable bulge or defect that appears after removal of the appliance during the Valsalva maneuver (photodocumentation)

ii) sonographically diagnosed parastomal hernia (definition: protrusion of intraabdominal contents adjacent to the stoma)

iii) intraoperative finding during stoma reversal (questionnaire for the surgeon)

Secondary endpoints:

  • Stoma-related morbidity (according to Dindo 2004): high-output stoma (> 2000 ml/day), ileus, stenosis, obstruction, prolapse, necrosis, retraction, fistulization, skin complications

Stratification into complications which can be managed in the ambulatory setting (clinic, outpatient wound therapy, outpatient stoma therapy) versus complications which require hospitalization and perhaps even surgical intervention/revision

  • Quality of Life (assessed by the EORTC questionnaires QLQ-CR29 and QLQ-C30)

Starting dateApril 2012
Contact information

Julia Hardt, MD, and Florian Herrle, MD

Dept. of General, Visceral, Vascular, Thoracic and Transplantation Surgery, University Medical Center Mannheim (UMM), University of Heidelberg, Theodor-Kutzer-Ufer 1-3, 68167 Mannheim, Germany

Phone: + 49-(621)-383-1501, Fax: +49-(621)-383-3809

Emails: julia.hardt@umm.de, florian.herrle@umm.de

NotesDRKS-ID: DRKS00003534