Wound drains after incisional hernia repair

  • Review
  • Intervention

Authors

  • Kurinchi Selvan Gurusamy,

    Corresponding author
    1. Royal Free Campus, UCL Medical School, Department of Surgery, London, UK
    • Kurinchi Selvan Gurusamy, Department of Surgery, Royal Free Campus, UCL Medical School, Royal Free Hospital,, Rowland Hill Street, London, NW3 2PF, UK. kurinchi2k@hotmail.com.

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  • Victoria B Allen

    1. Oxford University Hospitals NHS Trust, Oxford University Clinical Academic Graduate School, Oxford, UK
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Abstract

Background

Incisional hernias are caused by the failure of the wall of the abdomen to close after abdominal surgery, leaving a hole through which the viscera protrude. Incisional hernias are repaired by further surgery. Surgical drains are frequently inserted during hernia repair with the aim of facilitating fluid drainage and preventing complications. Traditional teaching has recommended the use of drains after incisional hernia repair other than for laparoscopic ventral hernia repair. More than 50% of open mesh repairs of ventral hernias have drains inserted. However, there is uncertainty as to whether drains are associated with benefits or harm to the patient.

Objectives

To determine the effects on wound infection and other outcomes, of inserting a wound drain during surgery to repair incisional hernias, and, if possible, to determine the comparative effects of different types of wound drain after incisional hernia repair.

Search methods

In November 2013, for this fourth update we searched the Cochrane Wounds Group Specialised Register, the Cochrane Central Register of Controlled Trials (CENTRAL), The Cochrane Library, Ovid MEDLINE, Ovid EMBASE, and EBSCO CINAHL.

Selection criteria

We considered all randomised trials performed in adult patients who underwent incisional hernia repair and that compared using a drain with no drain. We also considered trials that compared different types of drain.

Data collection and analysis

We extracted data on the characteristics of the trial, methodological quality of the trials, outcomes (e.g. infection and other wound complications) from each trial. For each outcome, we calculated the risk ratio (RR) with 95% confidence intervals (CI) and based on intention-to-treat analysis.

Main results

No new trials were identified by the updated searches. Only one trial was eligible for inclusion in the review with a total of 24 patients randomised to an electrified drain (12 patients) compared with a corrugated drain (12 patients). There were no statistically significant differences between the groups for wound infection or in the length of stay in hospital.

Authors' conclusions

There is insufficient evidence to determine whether wound drains after incisional hernia repair are associated with better or worse outcomes than no drains.

Résumé scientifique

Drains de plaies après la réparation d'une hernie incisionnelle

Contexte

Les hernies incisionnelles sont dues à une mauvaise cicatrisation de la paroi abdominale après une chirurgie abdominale, laissant place à un orifice dans lequel on observe une protrusion viscérale. Les hernies incisionnelles sont réparées grâce à une intervention chirurgicale supplémentaire. Des drains chirurgicaux sont couramment insérés pendant la réparation d'une hernie afin de faciliter le drainage des liquides et éviter toute complication. L'approche classique recommande l'utilisation de drains suite à la réparation d'une hernie incisionnelle autre que la réparation d'une hernie ventrale par laparoscopie. Des drains sont insérés dans plus de 50 % des réparations ouvertes avec résille des hernies ventrales. Toutefois, on ignore si ces drains sont bénéfiques ou nocifs pour le patient.

Objectifs

Déterminer les effets, au niveau de l'infection des plaies et d'autres résultats, liés à l'insertion d'un drain de plaies au cours d'une intervention chirurgicale pour la réparation d'hernies incisionnelles et, si possible, déterminer les effets comparatifs de différents types de drains de plaies après la réparation d'une hernie incisionnelle.

Stratégie de recherche documentaire

En novembre 2013, pour cette quatrième mise à jour, nous avons effectué des recherches dans le registre spécialisé du groupe Cochrane sur les plaies et les contusions, le registre Cochrane des essais contrôlés (CENTRAL), The Cochrane Library numéro, Ovid MEDLINE, Ovid EMBASE et EBSCO CINAHL.

Critères de sélection

Nous avons pris en compte tous les essais randomisés réalisés chez des patients adultes, qui ont fait l'objet d'une réparation d'une hernie incisionnelle, comparant l'utilisation d'un drain à l'absence de drain. Nous avons également tenu compte des essais comparant différents types de drains.

Recueil et analyse des données

Nous avons extrait des données relatives aux caractéristiques de chaque essai, leur qualité méthodologique et leurs critères de résultats (par ex. : infections et autres complications de cicatrisation). Pour chaque critère de résultat, nous avons calculé le risque relatif (RR) avec des intervalles de confiance (IC) à 95 % sur la base d'une analyse en intention de traiter.

Résultats principaux

Aucun nouvel essai n'a été identifié par les recherches mises à jour. Un seul essai était éligible pour être inclus dans la revue et totalisait 24 patients randomisés à un drain électrique (12 patients) comparés à ceux randomisés à un drain multitubulé (12 patients). Il n'y avait aucune différence statistiquement significative entre les groupes en termes d'infection de la plaie ou de durée d'hospitalisation.

Conclusions des auteurs

Les preuves sont insuffisantes pour déterminer si les drains de plaies insérés après la réparation d'une hernie incisionnelles améliorent ou aggravent les résultats par rapport à l'absence de drains.

Plain language summary

Using wound drains after incisional hernia repair

Incisional hernias are caused by the failure of the wall of the abdomen to close after abdominal surgery. This leaves a hole through which the viscera (guts) protrude. Hernias are repaired with further surgery, during which the insertion of a drain to remove excess fluid is common practice. It is not known whether or not these drains help the wounds to heal. Drains may produce undesired results such as an increased risk of infection, pain, and an increased length of hospital stay after surgery. We reviewed all the available trial evidence to see whether drains help or hinder recovery after operations for incisional hernia repair. We found that no trials that compared people who had drains inserted for this type of surgery against those who did not. One trial compared two types of drain against each other, and both models of drain performed similarly well. Further trials need to be carried out before being able to answer the question about the benefits, or otherwise, of drains inserted during repair of incisional hernias.

Résumé simplifié

Utilisation de drains de plaies après la réparation d'une hernie incisionnelle

Les hernies incisionnelles sont dues à une mauvaise cicatrisation de la paroi abdominale après une chirurgie abdominale, laissant place à un orifice dans lequel on observe une protrusion viscérale (intestins). Les hernies peuvent être réparées grâce à une intervention chirurgicale au cours de laquelle un drain est généralement introduit pour absorber l'excès de liquides. On ignore si ces drains contribuent ou pas à la cicatrisation des plaies. Ils peuvent entraîner des résultats inattendus, comme une hausse des risques d'infection, des douleurs et une prolongation de l'hospitalisation suite à l'intervention chirurgicale. Nous avons passé en revue toutes les preuves des essais disponibles afin de déterminer si les drains contribuent à ou empêchent la guérison après une chirurgie de réparation d'une hernie incisionnelle. Nous n'avons trouvé aucun essai comparant l'insertion d'un drain pour ce type de chirurgie à l'absence de drain. Un essai comparait deux types de drains et l'efficacité de ces deux modèles de drains était semblable. Des essais supplémentaires doivent être réalisés avant de répondre à la question concernant les avantages, ou autres, liés à l'insertion de drains lors de la réparation d'hernies incisionnelles.

Notes de traduction

Traduit par: French Cochrane Centre 18th May, 2012
Traduction financée par: Ministère du Travail, de l'Emploi et de la Santé Français

Background

Description of the condition

A hernia is defined as the protrusion of abdominal viscera outside the abdominal cavity through a natural or acquired defect (Maingot 1997). Incisional hernias result from a failure of abdominal wall to close after abdominal surgery (Maingot 1997). Although the true incidence of incisional hernias after abdominal surgery is difficult to estimate (they can occur many years after surgery) (Ellis 1983; Mudge 1985), figures of between 5% and 11% have been suggested (Bucknall 1981; Ellis 1983; Milbourn 2004; Mudge 1985). The incidence of incisional hernias through laparoscopic port sites varies between 0.2% and 3% depending on the size of the port (Kadar 1993).

There are a variety of methods for repairing incisional hernias including resuturing the defect, shoelace darn repair (Maingot 1997), open prosthetic mesh repair (Chrysos 2000; Machairas 2004), modified Rives-Stoppa prosthetic repair (Bauer 2002; Ferranti 2003; Temudom 1996) and laparoscopic ventral hernia repair (Aura 2002; Eid 2003; Franklin 2004). While resuturing the defect and shoelace darn repair involve using the body's own tissues to repair the defect, the other methods involve use of prosthetic or biosynthetic mesh.

Resuturing the defect involves opening the sac (the redundant peritoneal lining covering the hernia), dissecting the contents from the sac, excising the sac to the edge of the defect (to expose the normal tissue of linea alba) and closing the abdomen with a monofilament non-absorbable suture material (Maingot 1997). Shoelace darn repair involves reconstructing a new linea alba (by suturing together a strip of fascia from the medial edge of each anterior rectus sheath) and drawing the flat muscles back to their former length by drawing closer together the lateral cut edges of the anterior rectus sheaths where the medial strips were split off (using continuous suture of heavy monofilament nylon that passes to and fro between the cut edges and that also substitutes functionally and anatomically for the missing anterior rectus sheaths)(Maingot 1997).

Open prosthetic mesh repair involves identifying the sac, dissecting the contents from the sac, excising the sac to the edge of the defect and using a prosthetic mesh to repair the defect (Chrysos 2000). The mesh could be placed on-lay (pre fascial mesh) or in-lay (end-on suturing of mesh to muscle) or sub-lay (in the subfascial plane)(Kingsnorth 2004). The modified Rives-Stoppa prosthetic repair is a sub-lay repair, placing the prosthetic mesh in the plane between the rectus abdominis muscle and the posterior rectus sheath (Bauer 2002). Laparoscopic ventral hernia repair involves creating a pneumoperitoneum, breaking down the adhesions between the sac and its contents and covering the defect using an appropriately sized prosthetic or porcine derived mesh (Franklin 2004) without dissecting out the sac (Aura 2002). Thus the mesh is intra-peritoneal.

Potential complications of incisional hernia surgery include hernia recurrence, infection, seromas, haematomas, adhesions, bowel obstruction and erosion of mesh into the bowel or urinary bladder (Maingot 1997).

Description of the intervention

When repairing incisional hernias, surgeons frequently insert a surgical drain to facilitate the drainage of fluid. Surgical drains may be either open or closed. An open drain is an artificial conduit that is left in the wound to allow drainage of fluids to the exterior (outside the body), for example, corrugated drain, Penrose drain and Yeates drain. A closed drains is an artificial conduit that is left in the wound to allow drainage of fluids into a closed container. Closed drains may be either suction drains, for example the Redon drain, or passive drains, for example the Robinson drain. Traditional teaching has recommended the use of drains after incisional hernia repair (George 1986; Keen 1994; Kirk 2000; Maingot 1997) other than for the laparoscopic ventral hernia repair (Aura 2002; Franklin 2004) and at present more than 50% of the wounds of open mesh repair of ventral hernia have drains inserted (White 1998).

How the intervention might work

Surgeons who advocate the use of drains argue that this procedure reduces the accumulation of blood and fluid (Perkins 1997; Scevola 2002). Some have suggested that haematomas are predisposing factors for the recurrence of incisional hernia (George 1986). Others, who do not drain routinely, suggest that use of drains does not alter the rate of fluid collection (White 1998) or influence hernia recurrence rates (Hesselink 1993). Some argue that haematomas or seromas occur in spite of the presence of drains (Debry 1999; Pai 1999; Shaha 1993). Some argue that the drain itself acts as a foreign body and increases the chances of infection (Karayacin 1997; Moro 1996; Pessaux 2003; Tabaqchali 1999; Tang 2001; White 1998). A drain also increases the length of stay in hospital (Benedetti 1997; Hurtado-Lopez 2001) and can also be associated with pain (Debry 1999).

Why it is important to do this review

We were not able to identify any previous reviews addressing the question of whether it is necessary to insert drains after incisional hernia repair. We therefore sought to reduce this uncertainty by summarising the available research evidence regarding the effects of inserting wound drains during surgery to repair incisional hernia.

Objectives

Primary objective

To determine the effects on wound infection and other outcomes of inserting a wound drain during surgery to repair incisional hernias compared with no wound drain.

Secondary objective

To determine the comparative effects of different types of wound drain after incisional hernia repair.

Methods

Criteria for considering studies for this review

Types of studies

Only randomised clinical trials (RCTs) of parallel study design, where the allocation concealment is adequate or not reported, were eligible for inclusion in this review. Quasi-randomised trials in which allocation is unconcealed (for example, date of birth, hospital record number, alternation) were not eligible for inclusion.

Types of participants

RCTs involving adults (over 18 years old) undergoing repair of primary or recurrent incisional hernia by any technique except laparoscopic ventral hernia mesh repair were eligible for inclusion. Studies of people undergoing laparoscopic ventral hernia mesh repair were excluded because, with this type of surgery, the dissection is in a different plane compared with the other procedures for incisional hernia (Aura 2002; Franklin 2004).

Types of interventions

Studies reporting the following comparisons were eligible for inclusion:

  • Wound drainage compared with no wound drainage after incisional hernia repair.

  • One type of wound drain compared with another type of wound drain after incisional hernia repair.

Types of outcome measures

For the purposes of this review, studies which reported the following outcomes were eligible:

Primary outcomes
  1. Wound infection (however defined by the authors). Where study authors had used the CDC criteria and classification of surgical site infection (Mangram 1999), we intended to report the rates of superficial and deep infections separately.

  2. Post-operative wound dehiscence or 'burst abdomen', defined as frank evisceration or covered by skin (Maingot 1997).

  3. Complications associated with the use of the drain: for example, drain migration and injury to internal organs; problems with drain removal, for example, drain retention.

  4. Quality of life.

Secondary outcomes
  1. Re-operation for wound healing complications such as haematoma, seroma.

  2. Hernia recurrence (however defined).

  3. Length of hospital stay.

Search methods for identification of studies

For the search methods used in the third update of this review see Appendix 1.

Electronic searches

In November 2013, for this fourth update, we searched the following databases:

  • Cochrane Wounds Group Specialised Register (searched 28 November 2013);

  • The Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2013, Issue 10);

  • Ovid MEDLINE (1946 to November Week 3 2013);

  • Ovid MEDLINE (In-Process & Other Non-Indexed Citations November 27, 2013);

  • Ovid EMBASE (1974 to 2013 November 27);

  • EBSCO CINAHL (1982 to 22 November 2013)

The following strategy was used to search CENTRAL:

#1 MeSH descriptor: [Drainage] explode all trees 1986
#2 MeSH descriptor: [Suction] explode all trees 733
#3 drain* 4782
#4 #1 or #2 or #3 5377
#5 MeSH descriptor: [Hernia, Ventral] explode all trees 148
#6 hernia*:ti,ab,kw 2517
#7 herniorrhaphy:ti,ab,kw 374
#8 #5 or #6 or #7 2599
#9 #4 and #8 54

The search strategies for Ovid MEDLINE, Ovid EMBASE and EBSCO CINAHL can be found in Appendix 2, Appendix 3 and Appendix 4 respectively. The Ovid MEDLINE search was combined with the Cochrane Highly Sensitive Search Strategy for identifying randomised trials in MEDLINE: sensitivity- and precision-maximizing version (2008 revision); Ovid format (Lefebvre 2011). We combined the EMBASE search with the Ovid EMBASE filter developed by the UK Cochrane Centre (Lefebvre 2011). The CINAHL searches were combined with the trial filters developed by the Scottish Intercollegiate Guidelines Network (SIGN) (SIGN 2010). No date or language restrictions were applied.

Searching other resources

The reference lists in identified studies were also searched in order to identify further studies. We contacted major manufacturers of wound drains to identify any ongoing or completed trials.

Data collection and analysis

Selection of studies

Two review authors independently assessed the titles and abstracts of the identified studies. We obtained full articles for all studies that potentially met the inclusion criteria and included all those that met the inclusion criteria. Any differences in opinion between review authors at this stage were resolved by discussion.

Data extraction and management

Two review authors independently extracted data for the outcomes listed and independently assessed the risk of bias of each trial, without masking of study author names. In addition, we extracted the following data for each study using a custom designed extraction form:

  • Language of publication.

  • Country where study conducted.

  • Baseline characteristics of participants by group.

  • Type of hernia repair.

  • Type of intervention (drain).

  • Details of the comparison intervention.

  • Co-interventions (by group).

  • Duration of follow up.

  • Inclusion and exclusion criteria.

We contacted the study authors regarding any unclear or missing information. We did not identify any studies that potentially shared the same patients, and so did not contact the authors of the studies to clarify this issue.

Differences (between review authors) in data extraction were also resolved by discussion.

Assessment of risk of bias in included studies

Assessment of risk of bias in the trial was based on guidelines in the Cochrane Handbook for Systematic Reviews of Interventions (Higgins 2011). If information was not available in the published study, we contacted the study authors in order to assess the trials correctly.

The elements of risk of bias assessment were: generation of allocation sequence, allocation concealment, blinding, incomplete data outcomes, selective data reporting, and other bias (for example: early stopping, baseline imbalance, source of funding), see Appendix 5 for explanation of the criteria.

We considered trials which were of low risk of bias in all the above domains as trials of low risk of bias.

Measures of treatment effect

We used the software package RevMan 5.0 provided by The Cochrane Collaboration. For dichotomous variables, we calculated the risk ratio (RR) with 95% confidence interval (CI). For continuous outcomes we planned to enter the mean and standard deviation data into RevMan and calculate the mean difference (MD) for outcomes such as hospital stay and the standardised mean difference (SMD) for outcomes such as quality of life which can be reported in different scales.

Unit of analysis issues

The unit of allocation was individual participants. We did not consider cluster-randomised trials for inclusion.

Dealing with missing data

We planned to use an "available case analysis" i.e. whether participants were analysed in the groups to which they were originally randomised (Hollis 1999; Higgins 2011) without imputing any data for the patients for whom the outcomes were not reported. In case the authors did not report the standard deviation for continuous outcomes (and if we were unable to obtain this information from authors), we planned to impute the standard deviation from standard error, confidence intervals, or p-values using formulae given in the Cochrane Handbook (Higgins 2011). If it was not possible to impute the standard deviation from these measures, we planned to use the maximum standard deviation for the same measure in other trials (Higgins 2011). When medians are reported without the means, we will not include the median as a substitute for mean in the meta-analysis (see also Sensitivity analysis ). However, there were no post-randomisation drop-outs or withdrawals from the trial included in this review effectively making this analysis into an "intention-to-treat analysis".

Assessment of heterogeneity

Since we identified only one study, we did not explore heterogeneity. If we had identified more studies, we planned to explore heterogeneity using Higgins I2 (Higgins 2002) and p-value from the chi-squared test.

Assessment of reporting biases

Duplicate publication bias

In case there were any doubts whether a trial has been published twice or more (by identifying common authors, centres, and interventions), we planned to check with the study authors whether the trial report had been duplicated.

Location bias

We planned to investigate whether effect estimate varied with the database from which the report was identified (MEDLINE indexed versus MEDLINE not indexed).

Language bias

We planned to investigate whether effect estimate varied with the language in which the article was published (English versus no English). If a trial report had been published in English and other language(s), it would have been considered to be published in English.

Publication bias

We planned to investigate whether effect estimate varied with the publication of the trial report (as full text) or not. Since there was only one trial included, we did not explore bias. We planned to explore bias through a funnel plot of effect estimates and the standard error of the effect estimate (Egger 1997) using RevMan 5.1. We planned to use asymmetry in funnel plot of study size against treatment effect to identify this bias. We also intended to perform linear regression approach described by Egger 1997 to determine the funnel plot asymmetry.

Data synthesis

We planned to perform the meta-analyses according to the recommendations of The Cochrane Handbook for Systematic Reviews of Interventions (Higgins 2011). We planned to use the Mantel-Haenzel's methods to perform the meta-analysis. We planned to use a random-effects model (DerSimonian 1986) and a fixed-effect model (DeMets 1987). In case of discrepancy between the two models we planned to report both results; otherwise we planned to report only the results from the fixed-effect model.

Subgroup analysis and investigation of heterogeneity

Since there was only one study, we were not able to perform subgroup analyses to explore the effects of aspects of trials at low risk, unclear risk or high risk of bias. We also could not perform a subgroup analysis of 'open' drains compared with no drain and 'closed' drains compared with no drain (an open drain being when an artificial conduit is left in the wound to allow fluids to drain outs of the body, for example, corrugated drain, Penrose drain, Yeates drain, whereas a closed drain is an artificial conduit left in the wound to allow drainage of fluids into a closed container). We were also unable to perform a subgroup analysis of trials including mesh repairs and those including tissue repairs for the same reason. For the subgroup analysis, we planned to use the inverse-variance method of meta-analysis and use the chi-squared test for identifying subgroup differences (Higgins 2011). We also planned to use meta-regression to investigate heterogeneity using factors such as type of drain, criterion of removal of drain (fixed duration versus drain volume), and prophylactic antibiotic use (antibiotic used, route, duration) if there were enough trials.

Sensitivity analysis

We planned to perform a sensitivity analysis of using medians directly in the meta-analysis and determine if this changes the results of the meta-analysis.

Results

Description of studies

For this third update we identified no new trials which were eligible for inclusion.

Previously, we had identified a total of 116 references through electronic searches. We had excluded 15 citations that had been retrieved more than once and 100 clearly irrelevant references through reading abstracts. Only one reference was retrieved in full for further assessment. No references had been identified through scanning reference lists of this article. No references had been identified through contacting the drain manufacturers. In the metaRegister of Controlled Trials (mRCT), we identified one ongoing trial which is still recruiting patients (NCT00478348), on completion, this trial will be considered for inclusion in the next available update.The one article that had been retrieved for further assessment was included in the review (Shafik 1993).

Participants
A total of 24 male participants, with moderate-sized incisional hernia (as described by author) at the site of stomal closure, were randomised in this trial. The mean age was 48 years ranging between 38 to 62 years of age.

Experimental intervention
Electrified drain: this consisted of a corrugated rubber to which two electrodes were applied. Each electrode was placed in separate drain gutter 5 mm apart, and protruded 1 cm beyond the distal end of the drain. The electrodes were made of silver chloride wire that was fixed to the drain by three 2/0 chromic catgut stitches at the proximal, middle and distal end of the drain. Both electrodes were connected to a small 9 volt battery, which was fastened to the abdomen by an adhesive strip. The duration of the drain was fixed for all patients and was 72 hours.

Control intervention
Corrugated rubber drain, with dummy electrodes to blind the patients. The duration of the drain was fixed for all the patients at 72 hours.

Outcome measures
The outcome measures reported in this trial which were of interest in this review were clinical infection (as defined by author - redness, oedema and purulent discharge) and length of hospital stay.

Risk of bias in included studies

The only study included in the review (Shafik 1993) had an adequate method of generation of allocation sequence (random number table). However, the extent of allocation concealment was unclear and although the author was contacted, and provided answers to all other questions, he did not address this specific question. The participants and the outcome-assessors were blinded but the care-provider was not blinded. There were no withdrawals or loss to follow-up. The main outcomes were reported. The source of funding was not stated. The risk of bias is summarised in Characteristics of included studies.

Effects of interventions

We did not identify any additional trials in updating this review. There were no RCTs identified that compared wound drainage with no wound drainage after incisional hernia repair. Only one trial (24 patients) was identified that compared two different types of drains (Shafik 1993). Twelve patients were randomised to the electrified drain group and 12 patients to the corrugated drain group.

Clinical infection (redness, oedema, purulent discharge - as defined by authors)

Two patients in the corrugated drain group and none of the patients in the electrified drain group developed clinical infection. There was no statistically significant difference between the two groups for this outcome (RR 0.20, 95% CI 0.01 to 3.77) (Analysis 1.1).

Secondary outcomes

There was no difference in length of hospital stay (10 to 14 days for both groups).

Discussion

There were no RCTs comparing wound drainage with no wound drainage after incisional hernia repair.

There was only one trial that compared two different types of drains after incisional hernia repair. There was no difference in any of the outcomes measured, however this trial involved only 24 patients and therefore was grossly underpowered to detect clinically important differences in outcome. Furthermore, we were unable to identify further published trials of electrified drains (not only in incisional hernia, but also in other fields of surgery), suggesting that these drains are not commonly used and that these results are currently not clinically relevant.

As previously discussed, the use of drains after incisional hernia repair is controversial. However, we did not find any randomised trial evidence to enable us to recommend or advise against the use of drains. However, randomised trials are necessary to justify the continued use of drains in incisional hernia.

A sample size of 480 (240 in each group) would be required to detect an absolute reduction in infection rates of 9% (White 1998, observational study, from 19% to 10%) at 80% power and an alpha-error set at 0.05 (Stats Direct 2.5.6). The period of follow-up should be long enough to identify at least the early recurrence (at least one year). Such a randomised trial should follow the recommendations of modified Consort Statement (http://www.consort-statement.org/Statement/revisedstatement.htm) in order to ensure that the trial is reported correctly.

Authors' conclusions

Implications for practice

There is an absence of evidence for or against the use of drains after incisional hernia repair.

Implications for research

It is surprising that we have identified no research evidence relating to this commonly used intervention. RCTs are needed to establish whether there is any clinical benefit of inserting wounds drains after repair of incisional hernias.

Acknowledgements

We would like to thank:

  1. M.J. Parker, first author on more than 15 Cochrane reviews, who taught the first author how to write a scientific paper and created his interest in writing Cochrane reviews.

  2. Sally Bell-Syer, the Cochrane Wounds Group Managing Editor, for her guidance.

  3. The referees Suzanne Hartley, Stephanie Kondos, Gill Cranny, Lars Naver and Erik Nilsson and Wounds Group editors Nicky Cullum and Andrew Jull for their comments on the review.

  4. Copy Editor, Elizabeth Royle.

  5. Dr Ahmed Shafiq, who answered most of the questions related to his study.

  6. Ruth Foxlee, Trial Search Coordinator of the Wounds Group who ran the searches for the review updates.

  7. K Samraj who independently extracted data and assessed study quality for the first publication and the two previous updates.

Data and analyses

Download statistical data

Comparison 1. Electrified drain vs corrugated drain
Outcome or subgroup titleNo. of studiesNo. of participantsStatistical methodEffect size
1 Clinical infection (redness, oedema, purulent discharge)124Risk Ratio (M-H, Fixed, 95% CI)0.2 [0.01, 3.77]
Analysis 1.1.

Comparison 1 Electrified drain vs corrugated drain, Outcome 1 Clinical infection (redness, oedema, purulent discharge).

Appendices

Appendix 1. Search strategy for the third update of the review - 2011

Electronic searches

For the third update, we searched the following databases:

  • Cochrane Wounds Group Specialised Register (searched 8 September 2011);

  • The Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2011, Issue 8);

  • Ovid MEDLINE (2010 to August Week 5 2011);

  • Ovid MEDLINE (In-Process & Other Non-Indexed Citations September 07, 2011);

  • Ovid EMBASE (2010 to 2011 Week 35);

  • EBSCO CINAHL (2010 to 2 September 2011)

The following strategy was used to search CENTRAL:

#1 MeSH descriptor Drainage explode all trees
#2 MeSH descriptor Suction explode all trees
#3 drain*
#4 (#1 OR #2 OR #3)
#5 MeSH descriptor Hernia, Ventral explode all trees
#6 hernia*:ti,ab,kw
#7 herniorrhaphy:ti,ab,kw
#8 (#5 OR #6 OR #7)
#9 (#4 AND #8)

The search strategies for Ovid MEDLINE, Ovid EMBASE and EBSCO CINAHL can be found in Appendix 2, Appendix 3 and Appendix 4 respectively. The Ovid MEDLINE search was combined with the Cochrane Highly Sensitive Search Strategy for identifying randomised trials in MEDLINE: sensitivity- and precision-maximizing version (2008 revision); Ovid format (Lefebvre 2011). The EMBASE and CINAHL searches were combined with the trial filters developed by the Scottish Intercollegiate Guidelines Network (SIGN) (SIGN 2010). No date or language restrictions were applied.

We also searched the metaRegister of Controlled Trials (mRCT) (September 2011).

Searching other resources

The reference lists in identified studies were also searched in order to identify further studies. We contacted major manufacturers of wound drains to identify any ongoing or completed trials.

Appendix 2. Ovid MEDLINE search strategy

1 exp Drainage/ (44681)
2 exp Suction/ (10365)
3 drain*.tw. (87420)
4 or/1-3 (111941)
5 exp Hernia, Ventral/ (7689)
6 hernia*.tw. (50565)
7 herniorrhaphy.tw. (1780)
8 or/5-7 (54010)
9 4 and 8 (1156)

Appendix 3. Ovid EMBASE search strategy

1 exp Wound Drainage/ (18268)
2 exp Suction Drainage/ (1501)
3 drain*.tw. (120785)
4 or/1-3 (130740)
5 exp Abdominal Wall Hernia/ (24759)
6 hernia*.tw. (65425)
7 exp Herniorrhaphy/ (2812)
8 herniorrhaphy.tw. (2118)
9 or/5-8 (72627)
10 4 and 9 (1520)

Appendix 4. EBSCO CINAHL search strategy

S9 S4 and S8
S8 S5 or S6 or S7
S7 TI herniorrhaphy or AB herniorrhaphy
S6 TI hernia* or AB hernia*
S5 (MH "Hernia+")
S4 S1 or S2 or S3
S3 TI drain* or AB drain*
S2 (MH "Suction+")
S1 (MH "Drainage+")

Appendix 5. Risk of bias criteria

1.  Was the allocation sequence randomly generated?

Low risk of bias

The investigators describe a random component in the sequence generation process such as: referring to a random number table; using a computer random number generator; coin tossing; shuffling cards or envelopes; throwing dice; drawing of lots.

High risk of bias

The investigators describe a non-random component in the sequence generation process. Usually, the description would involve some systematic, non-random approach, for example: sequence generated by odd or even date of birth; sequence generated by some rule based on date (or day) of admission; sequence generated by some rule based on hospital or clinic record number.

Unclear

Insufficient information about the sequence generation process to permit judgement of low or high risk of bias.

2.  Was the treatment allocation adequately concealed?

Low risk of bias

Participants and investigators enrolling participants could not foresee assignment because one of the following, or an equivalent method, was used to conceal allocation: central allocation (including telephone, web-based and pharmacy-controlled randomisation); sequentially-numbered drug containers of identical appearance; sequentially-numbered, opaque, sealed envelopes.

High risk of bias

Participants or investigators enrolling participants could possibly foresee assignments and thus introduce selection bias, such as allocation based on: using an open random allocation schedule (e.g. a list of random numbers); assignment envelopes were used without appropriate safeguards (e.g. if envelopes were unsealed or non opaque or not sequentially numbered); alternation or rotation; date of birth; case record number; any other explicitly unconcealed procedure.

Unclear

Insufficient information to permit judgement of low or high risk of bias. This is usually the case if the method of concealment is not described or not described in sufficient detail to allow a definite judgement, for example if the use of assignment envelopes is described, but it remains unclear whether envelopes were sequentially numbered, opaque and sealed.

3.  Blinding - was knowledge of the allocated interventions adequately prevented during the study?

Low risk of bias

Any one of the following.

  • No blinding, but the review authors judge that the outcome and the outcome measurement are not likely to be influenced by lack of blinding.

  • Blinding of participants and key study personnel ensured, and unlikely that the blinding could have been broken.

  • Either participants or some key study personnel were not blinded, but outcome assessment was blinded and the non-blinding of others unlikely to introduce bias.

High risk of bias

Any one of the following.

  • No blinding or incomplete blinding, and the outcome or outcome measurement is likely to be influenced by lack of blinding.

  • Blinding of key study participants and personnel attempted, but likely that the blinding could have been broken.

  • Either participants or some key study personnel were not blinded, and the non-blinding of others likely to introduce bias.

Unclear

Any one of the following.

  • Insufficient information to permit judgement of low or high risk of bias.

  • The study did not address this outcome.

4. Were incomplete outcome data adequately addressed?

Low risk of bias

Any one of the following.

  • No missing outcome data.

  • Reasons for missing outcome data unlikely to be related to true outcome (for survival data, censoring unlikely to be introducing bias).

  • Missing outcome data balanced in numbers across intervention groups, with similar reasons for missing data across groups.

  • For dichotomous outcome data, the proportion of missing outcomes compared with observed event risk not enough to have a clinically relevant impact on the intervention effect estimate.

  • For continuous outcome data, plausible effect size (difference in means or standardised difference in means) among missing outcomes not enough to have a clinically relevant impact on observed effect size.

  • Missing data have been imputed using appropriate methods.

High risk of bias

Any one of the following.

  • Reason for missing outcome data likely to be related to true outcome, with either imbalance in numbers or reasons for missing data across intervention groups.

  • For dichotomous outcome data, the proportion of missing outcomes compared with observed event risk enough to induce clinically relevant bias in intervention effect estimate.

  • For continuous outcome data, plausible effect size (difference in means or standardised difference in means) among missing outcomes enough to induce clinically relevant bias in observed effect size.

  • ‘As-treated’ analysis done with substantial departure of the intervention received from that assigned at randomisation.

  • Potentially inappropriate application of simple imputation.

Unclear

Any one of the following.

  • Insufficient reporting of attrition/exclusions to permit judgement of low or high risk of bias (e.g. number randomised not stated, no reasons for missing data provided).

  • The study did not address this outcome.

5. Are reports of the study free of suggestion of selective outcome reporting?

Low risk of bias

Any of the following.

  • The study protocol is available and all of the study’s pre-specified (primary and secondary) outcomes that are of interest in the review have been reported in the pre-specified way.

  • The study protocol is not available but it is clear that the published reports include all expected outcomes, including those that were pre-specified (convincing text of this nature may be uncommon)

High risk of bias

Any one of the following.

  • Not all of the study’s pre-specified primary outcomes have been reported.

  • One or more primary outcomes is reported using measurements, analysis methods or subsets of the data (e.g. subscales) that were not pre-specified.

  • One or more reported primary outcomes were not pre-specified (unless clear justification for their reporting is provided, such as an unexpected adverse effect).

  • One or more outcomes of interest in the review are reported incompletely so that they cannot be entered in a meta-analysis.

  • The study report fails to include results for a key outcome that would be expected to have been reported for such a study.

Unclear

Insufficient information to permit judgement of low or high risk of bias. It is likely that the majority of studies will fall into this category.

6. Other sources of potential bias

Low risk of bias

The study appears to be free of other sources of bias.

High risk of bias

There is at least one important risk of bias. For example, the study:

  • had a potential source of bias related to the specific study design used; or

  • had extreme baseline imbalance; or

  • has been claimed to have been fraudulent; or

  • had some other problem.

Unclear

There may be a risk of bias, but there is either:

  • insufficient information to assess whether an important risk of bias exists; or

  • insufficient rationale or evidence that an identified problem will introduce bias.

What's new

DateEventDescription
10 December 2013New search has been performedFourth update, new search, no new trials identified.
10 December 2013New citation required but conclusions have not changedConclusions remain unchanged.

History

Protocol first published: Issue 1, 2006
Review first published: Issue 1, 2007

DateEventDescription
22 November 2011New citation required but conclusions have not changedNew author added to the review team.
22 November 2011New search has been performedThird update, new search, no new trials identified.
11 May 2010AmendedContact details updated.
20 January 2010New search has been performedNew search, no new trials were identified, conclusions remain unchanged.
26 March 2008New search has been performedSearch has been updated in March 2008. Methods of assessment of risk of bias have been updated to reflect the new guidelines on assessment of bias risk. Statistical sections on how new studies will be handled has been revised. There is no change to the discussion or the conclusion of the review.
25 March 2008AmendedContact details updated.
20 March 2008AmendedConverted to new review format.
4 October 2006New citation required and conclusions have changedSubstantive amendment

Contributions of authors

K Gurusamy wrote the protocol, contacted the trial author and drain manufacturers, searched the trials register, performed the meta-analysis, wrote the review and undertook all updates of the review.
V Allen independently searched the references for inclusion and extracted the data for the third update. She also helped in the revision of outcomes.

Declarations of interest

None.

Sources of support

Internal sources

  • University College London, UK.

External sources

  • NIHR/Department of Health (England), (Cochrane Wounds Group), UK.

Differences between protocol and review

Differences between previous versions and current version: The review was updated according to the current Cochrane handbook (Higgins 2011). In particular, the outcomes were revised. Only important clinical outcomes irrespective of whether they were reported were included in this review. Surrogate outcomes such as the growth of organisms from culture were removed. Requirement for antibiotic was removed from the list of outcomes since all clinical infections require treatment.

Characteristics of studies

Characteristics of included studies [ordered by study ID]

Shafik 1993

MethodsRandomised clinical trial (parallel study design)
ParticipantsCountry: Egypt.
Number randomised: 24.
Mean age: 48 years.
Females: 0 (0%).
Patients with incisional hernia following stoma closure.
Interventions

Participants were randomly assigned to two groups.
Group 1: Electrified drain (n = 12).
Group 2: Corrugated drain (n = 12).

Co-interventions: all patients had a three day course of antibiotics post-operatively.
All were tissue repairs.

Outcomes1. Infection (>10,000 organisms per ml in culture of swab from drain site).
2. Clinical infection (redness, oedema and purulent discharge).
3. Need for additional course of antibiotics.
NotesContacted author to obtain information regarding allocation sequence, allocation concealment, blinding and hospital stay.
Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Low riskQuote: "Random number table" (author replies).
Allocation concealment (selection bias)Unclear riskComment: This information could not be obtained.
Blinding of participants and personnel (performance bias)
All outcomes
High risk

Quote: "Participants and outcome assessors were blinded by use of dummy electrodes".

Comment: The surgeons were not blinded to the groups.

Blinding of outcome assessment (detection bias)
All outcomes
Low risk

Quote: "Participants and outcome assessors were blinded by use of dummy electrodes".

Comment: Since the participants or the outcome assessors could not determine whether the drain was electrified, they were adequately blinded.

Incomplete outcome data (attrition bias)
All outcomes
Low riskComment: There were no drop-outs or withdrawals after randomisation (author replies).
Selective reporting (reporting bias)Low riskComment: Important primary outcome namely wound infection was reported.
No bias due to source of funding?Unclear riskComment: The source of funding was not stated.

Characteristics of ongoing studies [ordered by study ID]

NCT00478348

Trial name or titleShould Prosthetic Repair of Incisional Abdominal Hernias be Drain or Not?
MethodsPrevention, Randomized, Open Label, Active Control, Parallel Assignment, Safety/Efficacy Study
Participants

Inclusion Criteria:

  1. Clinical diagnosis of midline abdominal wall incisional hernia

  2. Adults of 20 to 80 years old

  3. ASA I to III

  4. Inform consent signed by the patient and investigators

Exclusion Criteria:

  1. Incisional hernia less than 2 cm

  2. Groin hernia

  3. Antibiotic treatment before and during hospital admission

  4. Emergency admission for strangulated incisional hernia

  5. Immunosuppressing treatment

InterventionsInsertion of three drains (Redon)
OutcomesEvidence of early clinical infection, hematoma, seroma or recurrence confirmed by ultrasonography or/and laboratory findings at 30 days
Starting dateMay 2007
Contact informationAlexandre Paroz, MD
Department of Visceral Surgery, University Hospital Center, Lausanne, Vaud, 1011
telephone: +41 21 314 52 34
alexandre.paroz@chuv.ch
Notes 

Ancillary