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Abstract

  1. Top of page
  2. Abstract
  3. Introduction
  4. Methods
  5. Results
  6. Discussion
  7. Disclosure
  8. References
  9. Supporting Information

Background:

Single-incision laparoscopic cholecystectomy (SILC) may offer advantages over conventional laparoscopic cholecystectomy (LC).

Methods:

MEDLINE, Embase, PubMed, CINAHL, Cochrane Central Register of Controlled Trials and the Cochrane Library were searched for randomized clinical trials on SILC versus LC until May 2012. Odds ratio (OR) and weight mean difference (WMD) were calculated with 95 per cent confidence intervals (c.i.) based on intention-to-treat analysis.

Results:

Thirteen randomized clinical trials included a total of 923 procedures. SILC had a higher procedure failure rate than LC (OR 8·16, 95 per cent c.i. 3·42 to 19·45; P < 0·001), required a longer operating time (WMD 16·55, 95 per cent c.i. 9·95 to 23·15 min; P < 0·001) and was associated with greater intraoperative blood loss (WMD 1·58, 95% of c.i. 0·44 to 2·71 ml; P = 0·007). There were no differences between the two approaches in rate of conversion to open surgery, length of hospital stay, postoperative pain, adverse events, wound infections or port-site hernias. Better cosmetic outcomes were demonstrated in favour of SILC as measured by Body Image Scale questionnaire (WMD − 0·97, 95% of c.i. − 1·51 to − 0·43; P < 0·001) and Cosmesis score (WMD − 2·46, 95% of c.i. − 2·95 to − 1·97; P < 0·001), but this was based on comparison with procedures in which multiple and often large ports (10 mm) were used.

Conclusion:

SILC has a higher procedure failure rate with more blood loss and takes longer than LC. No trial was adequately powered to assess safety. Copyright © 2012 British Journal of Surgery Society Ltd. Published by John Wiley & Sons, Ltd.


Introduction

  1. Top of page
  2. Abstract
  3. Introduction
  4. Methods
  5. Results
  6. Discussion
  7. Disclosure
  8. References
  9. Supporting Information

Laparoscopic cholecystectomy (LC) is largely accepted as the standard procedure for treating benign gallbladder disease1. Single-incision laparoscopic cholecystectomy (SILC) was first described in 19952, but it has not enjoyed widespread use to date. This approach emerged as a form of natural orifice surgery, but criticisms have been raised3 and some surgeons are still reluctant to utilize this type of approach if its safety has not been established4–6. Although the introduction of SILC into the surgical community dates back to the mid-1990s, the evidence supporting this minimally invasive technique is still based largely on the results of small observational studies5, 7–10. Current UK National Institute for Health and Clinical Excellence guidelines, published in May 2010, affirmed: ‘Current evidence on the safety and efficacy of single-incision laparoscopic cholecystectomy (SILC) is limited to small numbers of patients. Since the main potential advantage to patients of this procedure is cosmetic, there is a particular need for good safety data. Therefore this procedure should only be used with special arrangements for clinical governance, consent and audit or research’.

Two well conducted meta-analyses have already compared SILC with conventional LC4, 11. The first, by Markar and colleagues11, which analysed seven studies (375 operations), six randomized12–17 and one quasi-randomized18, suggested that SILC is a safe technique. Clearly, as suggested by the same authors, the data were not mature or numerous enough to make firm conclusions. There was no meta-analysis of cosmetic results or quality of life (QoL) and postoperative pain was evaluated only on the day of surgery. A more recent meta-analysis by Garg and co-workers4 including nine randomized clinical trials (RCTs) (659 procedures) concluded that SILC does not confer any benefits in terms of postoperative pain and hospital stay. According to these authors, SILC has postoperative complications similar to those of LC, but better cosmetic results.

In view of the shortcomings of previous analyses due to the lack of the published RCTs on this topic and for the availability of data from a further four RCTs19–22, it was considered necessary to perform a thorough meta-analysis to compare all available data.

Methods

  1. Top of page
  2. Abstract
  3. Introduction
  4. Methods
  5. Results
  6. Discussion
  7. Disclosure
  8. References
  9. Supporting Information

This review was conducted in accordance with the guidelines of the Quality of Reporting of Meta-analysis (QUORUM)23 statement and Cochrane Handbook for Systematic Reviews of Interventions24.

Literature search

Two authors performed an online bibliographical search of the MEDLINE, Embase, PubMed, Cumulative Index to Nursing and Allied Health Literature (CINAHL), Cochrane Central Register of Controlled Trials and Cochrane Library databases (to May 2012). The following medical subject heading (MeSH) terms and words was used for the search, in all possible combinations: ‘cholecystectomy’, ‘LESS’, ‘SILC’, ‘SILS’, ‘single port’, ‘transumbilical’, ‘single incision’, ‘single access’, ‘single site’ and ‘Triport’. We used the filter suggested by Cochrane Collaboration24 for the selection of RCTs in Medline and Embase database.

The ‘related article’ function was used to expand the search. We also performed a manual search of the Google Scholar database and six high-impact journals, from January 1997 to May 2012 (Annals of Surgery, British Journal of Surgery, Surgery, Archives of Surgery, Surgical Endoscopy and Journal of the American College of Surgeons). The reference lists of articles selected for full-text review were searched for additional articles. In the event of overlap of authors, institutions or patients, the most recent or highest-quality article was chosen.

Study selection

SILC was defined as laparoscopic excision of the gallbladder performed through a single abdominal incision using either a multiport device or different individual ports through the same single skin incision. LC was defined as a conventional multiple-incision procedure performed with the use of three or four ports through the same number of abdominal incisions irrespective of their size and location.

Studies were considered for inclusion if: they were RCTs (irrespective of publication status, language, sample size or blinding), they compared SILC with LC for benign gallbladder disease irrespective of type of surgical care (emergency or elective), and they reported at least one of the outcomes considered in the meta-analysis.

Studies were not considered in the meta-analysis if: they did not report at least one outcome of interest or it was impossible to calculate these, they reported the outcomes of procedures using minilaparoscopic instruments or natural-orifice transluminal endoscopic surgery techniques, or they included patients aged less than 18 years.

Two authors evaluated the titles and abstracts of the studies found with the online research. Those considered irrelevant were excluded and full texts of potentially suitable articles were retrieved. The same authors determined whether these articles satisfied the inclusion criteria for this systematic review.

Data extraction

Data from included RCTs were extracted by one author. A second author checked the extracted data and a third author was ask to resolve any disagreements. An intention-to-treat analysis was performed.

The primary purpose of this meta-analysis was to evaluate the feasibility of SILC compared with LC in terms of failure of the surgical technique. In the SILC group, procedure failure was defined as: addition of an extra port or needlescopic instruments through a second abdominal incision, conversion to LC or conversion to open surgery. In the LC group, failure of surgical technique was defined as conversion to open surgery, conversion to SILC (surgical procedure on a patient initially allocated to LC or in whom the procedure started with three or four ports but was then carried out through only one of them), or addition of an extra trocar or needlescopic instruments through a further abdominal incision.

In the comparison of SILC versus LC the following endpoints were considered as secondary outcomes. Intraoperative outcomes were: conversion to open surgery, duration of surgery and intraoperative blood loss (amount of blood lost during the operation). Postoperative outcomes were: length of hospital stay after operation, adverse events, wound infection, port-site hernia, mortality, early and late postoperative pain intensity, cosmetic outcomes and QoL measured using validated scales. Pain was measured using an 11-point visual analogue scale (VAS, ranging from 0 to 10). Postoperative pain intensity was considered to reflect abdominal pain at rest, unless specified otherwise. Early postoperative pain included assessments done between 2 and 72 h after surgery, whereas late postoperative pain was that evaluated from 72 h to 30 days after surgery.

Conversion was not considered as a complication. Procedures converted from SILC to LC, from LC to SILC, or from either SILC or LC to open surgery, were accounted for in the group of the technique initially planned (intention-to-treat analysis). If adverse events and/or mortality had not been reported, corresponding authors were contacted to obtain these data. The study was excluded from analysis of the outcome if the author failed to respond. The number of events was registered as zero only when it was specified clearly in the manuscript or confirmed by the corresponding author that no patient in either treatment group had experienced adverse events or died.

Assessment of methodological quality and bias risk of the included studies

Three reviewers assessed the methodological quality of all included RCTs by means of the modified Jadad scale25–27, and used the Cochrane Collaboration's tool to assess the risk of bias24. The weighted κ value was calculated to verify the agreement between authors regarding the risk of bias.

Statistical analysis

Quantitative statistical analysis for dichotomous variables was carried out using the odds ratio (OR) as the summary statistic with the Mantel–Haenszel method28, 29. The weighted mean difference (WMD) was used as the summary statistic for quantitative statistical analysis of continuous variables. OR and WMD values are reported with 95 per cent confidence intervals (c.i.). P < 0·050 was considered statistically significant. Where studies reported continuous data as medians with ranges, the mean and standard deviation were calculated using the methods described by Hozo and colleagues30; if only mean values were provided, standard deviations were obtained from the authors, or were calculated as described in the Cochrane handbook24.

Statistical heterogeneity was determined using the χ2 test, with P < 0·050 indicating statistically significant heterogeneity. Clinical heterogeneity was tested by means of the I2 value; a value exceeding 50 per cent was indicative of clinical heterogeneity. If heterogeneity was found, random-effects analysis was performed; otherwise the results of fixed-effects analysis are presented31. In the event of heterogeneity, sensitivity analysis was performed considering only trials of fair or good methodological quality according to the modified Jadad scale (at least 6 points)25–27. Funnel plots were used for investigating publication bias.

Subgroup analysis was performed, where possible, to assess the procedure failure rate between the two techniques, depending on the methods used to retract the gallbladder in SILC (anchoring it to the abdominal wall with a suture versus suspending it with an instrument), the types of laparoscopic instrument used in SILC (non-conventional, such as curved, flexible, roticulating, articulating instruments versus conventional ones) and the type of surgical care (emergency versus elective). Subgroup analyses of postoperative pain were carried out, considering separately SILC performed with the use of a single special SILC trocar device versus insertion of multiple trocars through the same number of fascial incisions (without use of special devices).

Meta-analysis was carried out using Review Manager version 5.0 (The Cochrane Collaboration, The Nordic Cochrane Centre, Copenhagen, Denmark). If meta-analysis of the data was not possible because of heterogeneity in measurement methods, descriptive (qualitative) analyses were carried out by reporting the number of studies finding a significant difference between the procedures (P < 0·050).

Results

  1. Top of page
  2. Abstract
  3. Introduction
  4. Methods
  5. Results
  6. Discussion
  7. Disclosure
  8. References
  9. Supporting Information

A flow diagram summarizing the systematic literature search is shown in Fig. 1. A total of 241 publications were identified through the electronic searches. A total of 218 studies were excluded as they were duplicates or irrelevant. Thirteen RCTs12, 14–17, 19–22, 32–35 were finally included in the meta-analysis. They included a total of 923 patients, 481 (52·1 per cent) in the SILC group and 442 (47·9 per cent) in the LC group. The RCT of Marks and colleagues16 was included, even though it reported preliminary data from the trial reported by Phillips and co-workers34, which was also included. This was decided because Marks et al. reported data on cosmetic outcomes in a form suitable for meta-analysis, whereas this was not possible with data from Phillips' study (as there was no response from corresponding author). Data from Marks and colleagues16 were included only in the meta-analysis of cosmesis evaluated by means of the Body Image Scale.

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Figure 1. QUORUM diagram of selection of articles for meta-analysis. RCT, randomized clinical trial; LC, conventional laparoscopic cholecystectomy; SILC, single-incision laparoscopic cholecystectomy

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Study characteristics

The characteristics of the included trials are summarized in Table 1. The trials were conducted in Asia, Europe and North America, and published between 1999 and 2012. Three were multicentre studies14, 16, 34. The sample size ranged from 34 to 197 patients. Eight studies reported sample size calculation by power analysis14–17, 21, 22, 33, 34. The power calculation was based only on pain scores (assessed by VAS) in four studies15, 17, 22, 33, on pain scores and cosmetic outcomes in one21, on QoL (calculated as a combination of LoS, postoperative pain, cosmetic results and SF-36 questionnaire results) in one14, and on safety in two16, 34.

Table 1. Characteristics of included trials
 No. of patients  Intraoperative cholangio- graphyProcedures with trocar addition  Conversion to open 
ReferenceSILCLCCountry YearPower calculations done/OutcomesSILCLCSILCLCConversion to SILCConversion to LCSILCLCfollow-up
  1. Values in parentheses are percentages. SILC, single-incision laparoscopic cholecystectomy; LC, conventional laparoscopic cholecystectomy; NR, not reported; ASA, American Society of Anesthesiologists; BMI, body mass index; VAS, visual analogue scale; GI, gastrointestinal; AST, aspartate aminotransferase; ALT, alanine aminotransferase; QoL, quality of life.

Aprea2525ItalyNo3 (12)2 (8)2 (8)1 (4)0 (0)0 (0)0 (0)0 (0)NR
 et al.12  2011          
Bresadola4545ItalyNo25 (56)32 (71)13 (29)0 (0)0 (0)0 (0)0 (0)0 (0)NR
 et al.19  1999          
Bucher7575SwitzerlandYes57 (76)62 (83)2 (3)0 (0)1 (1)0 (0)0 (0)0 (0)1 month
 et al.21  2011Postop. pain (VAS score) and cosmetic outcomes         
Cao5751ChinaNo0 (0)0 (0)0 (0)0 (0)0 (0)1 (2)1 (2)0 (0)1 month
 et al.32  2011          
Lai2427HongKongYesNRNR0 (0)0 (0)0 (0)0 (0)0 (0)0 (0)NR
 et al.33  2011Postop. pain (VAS score)         
Lirici2020ItalyYesNRNR2 (10)0 (0)0 (0)0 (0)0 (0)1 (5)1 month
 et al.14  2011Quality of life, postop. pain (VAS score), length of hospital         
     stay, cosmetic         
     score         
Ma et al.152122USAYes0 (0)0 (0)14 (67)0 (0)0 (0)0 (0)0 (0)0 (0)NR
   2011Postop. pain (VAS score)         
Marks5033USAYesNRNR0 (0)0 (0)0 (0)1 (2)0 (0)0 (0)Maximum
 et al.16  2011Safety        3 months
Mehmood3030PakistanNoNRNRNRNRNRNR0 (0)0 (0)NR
 et al.20  2010          
Philipps11780USAYesNRNR0 (0)0 (0)0 (0)1 (1)0 (0)0 (0)Maximum
 et al.34  2012Safety         12 months
Sinan1717TurkeyYes0 (0)0 (0)0 (0)0 (0)0 (0)0 (0)0 (0)0 (0)Median (weeks)
 et al.22  2012Postop. pain        29·9 SILC,
 (VAS score) 22·7 LC
Tsimoyiannis2020GreeceYes0 (0)0 (0)0 (0)0 (0)0 (0)0 (0)0 (0)0 (0)Mean
 et al.17  2010Postop. pain (VAS score)        38 months
Zheng3030ChinaNoNRNR0 (0)0 (0)0 (0)2 (7)0 (0)0 (0)Median (months),
 et al.35  2011         9·4 SILC 11·6 LC

Only seven studies reported the rate of intraoperative cholangiography12, 15, 17, 19, 21, 22, 32. This ranged from 0 per cent15, 17, 22, 32 to 76 per cent21 in the SILC group, and from 0 per cent15, 17, 22, 32 to 83 per cent in the LC group21. All of the included studies considered biliary complex disorders or acute gallbladder disease as exclusion criteria, except the study by Cao32, and none reported data on emergency cholecystectomy.

Among the SILC procedures, an extra trocar was added in a total of 33 patients (7·3 per cent). This occurred in 14 patients in the SILC group in the study by Ma and colleagues15, in which an extra 3-mm grasper was used through a new abdominal incision to retract the gallbladder during the dissection.

Bresadola and co-workers19 excluded data from a total of 25 randomized patients (8 LC, 17 SILC) from their analysis. Thirteen SILC procedures were excluded from the outcomes analysis because they required an extra port through a new abdominal incision (not intention-to-treat analysis).

Only four procedures, in the Cao (1)32, Phillips (1)34 and Zheng (2)35 studies, were converted from SILC to LC; the rate of conversion to LC ranged from 0 to 7 per cent. Only one LC procedure was converted to SILC, because dense and diffuse adhesions were discovered after placement of the first port21.

Technical details of the surgical procedures are described in Table 2. The number, size and location of the trocars used in LC were very heterogeneous. In only three studies included in the meta-analysis was LC performed with a three-port access technique12, 32, 35 whereas in the remainder a four-port access technique was preferred.

Table 2. Technical details of included trials
ReferenceNo., size and placement of trocars in LC proceduresTypes of trocar in SILC proceduresOptical for SILC proceduresTypes of instrument in SILC proceduresGallbladder retraction technique in SILC
  1. LC, conventional laparoscopic cholecystectomy; SILC, single-incision laparoscopic cholecystectomy; NR, not reported.

Aprea3TriPort Laparoscopic0° endoscopicConventional2/0 polypropylene suture
 et al.1212-mm umbilical, 12-mm left flank, 5-mm right flank Access Device (Olympus) (2 × 5-mm and 1 × 12-mm) camera with  flexible head  through abdominal wall subcostally at mid- clavicular line
Bresadola41 × 10-mm and30° angledRoticulatingPercutaneous anchorage
 et al.19(diameters and placement not reported) 1 × 5-mm ports through umbilical incision laparoscope  with 2 sutures
Bucher et al.214 2 × 5-mm and 2 × 10-mm, placement not specifiedTriPort (Advanced Surgical Concepts, Wicklow, Ireland) (2 × 5-mm and 1 × 12-mm)Deflectable tip endoscopeFlexibleAs in LC without suture to abdominal wall
Cao et al.323 2 × 10-mm, 1 × 5-mm1 × 10-mm and 2 × 5-mm ports through umbilical incision30° laparoscopeConventional2/0 polypropylene suture through abdominal wall subcostally at mid-clavicular line
Lai et al.334 10-mm umbilical, 5-mm subxiphoid, 5-mm right hypochondrium on mid-clavicular line, 5-mm right flank on anterior axillary lineSILS Port (Covidien, Norwalk, Connecticut, USA) (3 ports)30° laparoscopeConventionalCalot's triangle exposed with help of 2 slings of sutures over fundus and Hartmann's pouch
    or flexible  
    0° scope  
Lirici et al.144 12-mm umbilical, 12-mm left upper quadrant, 5-mm subxiphoid, 5-mm right flank midlineTriPort (Olympus America, Center Valley, Pennsylvania, USA) (2 × 5-mm and 1 × 12-mm)5-mm video endoscopeConventionalNeedlescopic grasper (1·8–3 mm in diameter) or transfixed suture of gallbladder fundus to abdominal wall only if  necessary
Ma et al.154 10-mm umbilical, 5-mm epigastric, 5-mm right hypochondrium mid-clavicular line, 5-mm right flank anterior axillary lineASC Triport (Advanced Surgical Concepts, Wicklow, Ireland)NRArticulatingConventional gallbladder retraction without suture
Marks et al.164 2 or 3 × 5-mm, 1 or 2 × 10-mm or 12-mm, placed at discretion of surgeonSILS Port (Covidien, Norwalk, Connecticut, USA) (3 ports)NRCurved or  articulatingConventional gallbladder retraction without suture
Mehmood et al.204 10-mm umbilical,10-mm epigastric, 2 × 5-mm right laterallySILS Port (Covidien) (3 ports)NRConventional or articulating2/0 polypropylene suture on straight needle introduced through abdominal wall to retract gallbladder fundus
Philipps et al.344 2 or 3 × 5-mm, 1 or 2 × 10-mm or 12-mm, placed at discretion of surgeonSILS Port (Covidien, Norwalk, Connecticut, USA) (3 ports)NRCurved orConventional gallbladder retraction without suture
     articulating 
Sinan et al.224 10-mm subumbilical, 10-mm subxiphoid area, 2 × 5-mm in right upper quadrantSingle port designed for SILC (Covidien, North Haven, Connecticut, USA)5-mm 30°RoticulatingExtracorporeal 3/0 polypropylene suture
    optical  
    device  
Tsimoyiannis et al.174 11-mm umbilical, 5-mm subxiphoid, 5-mm right hypochondrium mid-clavicular line, 5-mm right flank anterior axillary line1 × 10-mm trocar with 2 × 5-mm trocars through single umbilical incision10-mm 45°ConventionalOne straight-needle suture passed transabdominally into right subcostal plane and placed at gallbladder fundus for suspension
    long scope Only 
     endograsper 
     roticulator 
Zheng et al.353 10-mm umbilical, 10-mm subxiphoid, 5-mm right hypochondrium mid-  clavicular lineTriport (Advanced Surgical Concepts, Wicklow, Ireland)Rigid 30°, 10-mm laparoscopeConventionalInstrument in right hand used to retract the ampulla of gallbladder

Seven trials reported use of a suture to anchor the gallbladder to the abdominal wall in SILC12, 17, 19, 20, 22, 32, 33; in the remaining studies the gallbladder was retracted conventionally with instruments. Lirici and colleagues14 used a needlescopic grasper (1·8–3 mm in diameter) to facilitate exposure of Calot's triangle in difficult dissections; these authors did not consider the use of this instrument as a procedure failure. In contrast, this was considered as a procedure failure in the present meta-analysis as it involved the use of a further abdominal incision. Non-conventional laparoscopic instruments were used in eight trials15–17, 19–22, 34 (Table 2).

The length of follow-up ranged from 1 month14, 21, 32 to a maximum of 38 months (as reported by corresponding author)17 (Table 1).

Assessment of methodological quality and bias risk

Evaluation of the methodological quality of the included trials by means of the modified Jadad score found that ten studies were of fair quality (6–10 points)12, 15–17, 19, 20, 22, 32, 34, 35 and three of good quality (11–15 points)14, 21, 33. Table 3 shows the results of the bias risk assessment. All procedures were performed by surgeons expert in the laparoscopic approach but with different levels of expertise with SILC. The minimum number of SILC procedures performed by each surgeon before the beginning of the trial was fifty21, ten16, 34 and fewer than five15; this information was not reported in the other trials. There was a risk of underestimation of beneficial treatment (SILC) effects in RCTs with a high or unclear risk of operator bias.

Table 3. Risk of bias summary of included randomized clinical trials
ReferenceRandom sequence generation (selection bias)Allocation concealment (selection bias)Blinding of patients (performance bias)Blinding of outcome assessment (detection bias)Incomplete outcome data (attrition bias)Selective reporting (reporting bias)Operator biasOther bias
  1. +, Low risk of bias; −, high risk of bias; ?, uncertain risk of bias.

Aprea et al.12??+???
Bresadola et al.19???+?
Bucher et al.21+???++?
Cao et al.32++++??
Lai et al.33+++++??
Lirici et al.14++++++??
Ma et al.15+???++?
Marks et al.16+?+??+??
Mehmood et al.20?+??+??
Philipps et al.34+?+??+?+
Sinan et al.22+??++???
Tsimoyiannis et al.17???+????
Zheng et al.35+????+??

In four of the 13 trials the randomization process was unclear12, 17, 19, 20, whereas in the remaining studies an appropriate randomization process was used. In only four studies was concealment of allocation performed using appropriate methods14, 20, 32, 33; in the remaining studies the concealment of allocation process was unclear. Blinding involved both the patient and assessors of outcomes in only one study14. Two studies reported the blinding of patients alone16, 34, and four indicated that only the assessors were blinded17, 19, 32, 33. In one study, only nurses assessing the VAS score were blinded to the treatment22. No study had blinding of data analysis.

The study by Bresadola and colleagues19 had a high risk of attrition bias because the authors excluded a total of 25 patients from the overall analysis, 12 (8 SILC, 4 LC) with incomplete data and 13 from the SILC group who required insertion of an extra trocar through an additional abdominal incision (not intention-to-treat analysis).

Weighted κ values, calculated to evaluate the agreement for the items of the risk of bias, were: 0·94 for random sequence generation, 0·86 for allocation concealment, 1·00 for blinding of patients, 1·00 for blinding of outcome assessors, 0·90 for addressing incomplete data, 0·58 for selective reporting, 0·83 for operator bias and 0·64 for other bias. The overall risk of bias assessment and agreement between the reviewers is shown in Table 4.

Table 4. Overall assessment of risk of bias for each included trial
ReferenceRisk of bias
  1. κ = 0·89.

Aprea et al.12High
Bresadola et al.19High
Cao et al.32Unclear
Ma et al.15Unclear
Mehmood et al.20Unclear
Sinan et al.22Unclear
Tsimoyiannis et al.17Unclear
Zheng et al.35Unclear
Bucher et al.21Low
Lai et al.33Low
Lirici et al.14Low
Marks et al.16Low
Philipps et al.34Low

Intraoperative outcomes

Procedure failure

Eleven trials reported the number of patients requiring conversion to an open procedure or the addition of a port in SILC procedures, or conversion to LC or SILC procedures12, 14, 15, 17, 19, 21, 22, 32–35. The failure rate for SILC was 8·4 per cent, compared with 0·7 per cent in the LC group. The pooled OR was 8·16 (95 per cent c.i. 3·42 to 19·45) in favour of LC (P < 0·001) and there was no significant heterogeneity between studies (χ2 = 8·08, 7 d.f., I2 = 13 per cent) (Fig. 2).The funnel plot was symmetrical (not shown).

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Figure 2. Pooled estimate of rate of surgical failure of single-incision laparoscopic cholecystectomy (SILC) versus conventional laparoscopic cholecystectomy (LC). A Mantel–Haenszel fixed-effects model was used for meta-analysis. Odds ratios are shown with 95 per cent confidence intervals

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Considering SILC procedures in which the gallbladder was routinely anchored to the abdominal wall with a suture12, 17, 19, 22, 32, 33, the OR for failure compared with LC was 9·91 (2·33 to 42·19) in favour of LC (P = 0·002); there was no heterogeneity between studies (χ2 = 3·56, 2 d.f., I2 = 23 per cent). In studies in which the gallbladder was retracted conventionally with a grasper15, 21, 34, 35, there was a higher failure rate in the SILC group (OR 9·22, 2·63 to 32·27; P < 0·001), with no heterogeneity between studies (χ2 = 4·69, 3 d.f., I2 = 36 per cent).

Considering only the studies in which non-conventional laparoscopic instruments were used in the SILC group15, 19, 21, 22, 34, the OR for procedure failure was 14·93 (4·28 to 52·15) in favour of LC (P < 0·001), with no heterogeneity between studies (χ2 = 5·85, 3 d.f., I2 = 49 per cent). For studies in which the surgeons used conventional laparoscopic instruments in the SILC group12, 14, 32, 33, 35, the OR was 3·10 (0·81 to 11·81; P = 0·10), with no heterogeneity between studies (χ2 = 0·38, 3 d.f., I2 = 0 per cent).

Conversion to an open procedure

Twelve studies reported rates of conversion to open surgery for each procedure12, 14, 15, 17, 19–22, 32–35. The overall conversion rate was 0·2 per cent in both SILC and LC groups, and the meta-analysis did not show any significant differences between the two approaches (OR 0·94, 0·13 to 6·97; P = 0·96). There was no significant heterogeneity between studies (χ2 = 0·85, 1 d.f., I2 = 0 per cent) (Fig. 3). The funnel plot was symmetrical (not shown).

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Figure 3. Pooled estimate of rate of conversion to an open procedure for single-incision laparoscopic cholecystectomy (SILC) versus conventional laparoscopic cholecystectomy (LC). A Mantel–Haenszel fixed-effects model was used for meta-analysis. Odds ratios are shown with 95 per cent confidence intervals

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Duration of operation

All included studies reported the duration of operation. The pooled WMD was 16·55 (9·95 to 23·15) min in favour of LC (P < 0·001). The studies showed significant heterogeneity (χ2 = 103·79, 11 d.f., I2 = 89 per cent) (Fig. 4). The funnel plot was symmetrical (not shown).

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Figure 4. Pooled estimate of duration of operation for single-incision laparoscopic cholecystectomy (SILC) versus conventional laparoscopic cholecystectomy (LC). An inverse variance random-effects model was used for meta-analysis. *Values are mean(s.d.). Weighted mean differences (WMDs) are shown with 95 per cent confidence intervals

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Blood loss

Intraoperative blood loss was reported in six studies15, 17, 22, 32–34. The pooled WMD was 1·58 (0·44 to 2·71) ml in favour of LC (P = 0·007) and there was no heterogeneity between studies (χ2 = 3·64, 5 d.f., I2 = 0 per cent) (Fig. 5). The funnel plot was symmetrical (not shown).

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Figure 5. Pooled estimate of blood loss for single-incision laparoscopic cholecystectomy (SILC) versus conventional laparoscopic cholecystectomy (LC). An inverse variance fixed-effects model was used for meta-analysis. *Values are mean(s.d.). Weighted mean differences (WMDs) are shown with 95 per cent confidence intervals

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Postoperative outcomes

Hospital stay

Length of hospital stay was reported in all but two of the included trials22, 34. The pooled WMD among the studies that investigated this outcome was − 0·10 (−0·46 to 0·26) days in favour of SILC (P = 0·58). There was significant heterogeneity between the studies (χ2 = 133·80, 9 d.f., I2 = 93 per cent) (Fig. 6). The funnel plot was symmetrical (not shown).

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Figure 6. Pooled estimate of length of hospital stay for single-incision laparoscopic cholecystectomy (SILC) versus conventional laparoscopic cholecystectomy (LC). An inverse variance random-effects model was used for meta-analysis. *Values are mean(s.d.). Weighted mean differences (WMDs) are shown with 95 per cent confidence intervals

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Early postoperative pain

Eight trials investigated early postoperative abdominal pain intensity using an 11-point VAS (0–10 points), at various times during the first 72 h after surgery (2, 4, 6, 8, 12, 24, 48 and 72 h)12, 17, 19–22, 32, 33. Bresadola and colleagues19 reported the results of pain intensity scoring at 0, 4, 8, 12, 24 and 48 h in a graphical fashion and it was impossible to extract the raw data. These authors found a significant difference between the groups only at 8 and 12 h, in favour of SILC (P < 0·01).

Meta-analysis of the data amenable to pooling showed no significant reduction in pain scores at any the early time points. The overall WMD in early postoperative pain, based on a total of 1227 observations, was − 0·25 (−0·64 to 0·14) in favour of SILC (P = 0·22), but the heterogeneity between studies was high (χ2 = 424·40, 20 d.f., I2 = 95 per cent) (Fig. 7). The funnel plot was symmetrical (not shown).

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Figure 7. Pooled estimate of early postoperative abdominal pain a 2 h, b 4 h, c 6 h, d 8 h, e 12 h, f 24 h, g 48 h, h 72 h and i overall after single-incision laparoscopic cholecystectomy (SILC) versus conventional laparoscopic cholecystectomy (LC). An inverse variance random-effects model was used for meta-analysis. *Values are mean(s.d.) scores on a visual analogue scale ranging from 0 to 10. Weighted mean differences (WMDs) are shown with 95 per cent confidence intervals

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No difference in early postoperative pain between LC and SILC performed with a multiport device12, 20, 21, 22, 33 was demonstrated, with an overall WMD of − 0·05 (−0·75 to 0·65) in favour of SILC (P = 0·89); there was significant heterogeneity between studies (χ2 = 369·05, 11 d.f., I2 = 97 per cent). Comparison of LC with SILC procedures performed with the insertion of multiple ports through as many fascial incisions17, 32 (without use of a multiport device) showed a significant reduction in early postoperative pain in the SILC group, with an overall WMD of − 0·47 (−0·77 to − 0·17) (P = 0·002), but there was significant heterogeneity between the studies (χ2 = 45·22, 8 d.f., I2 = 82 per cent).

Late postoperative pain

Three studies reported the abdominal pain score intensity using an 11-point VAS (0–10 points) at various times more than 72 h after surgery21, 33, 35. Analysis of data amenable to pooling, based on 261 observations at several time points, showed an overall WMD in late postoperative pain score of − 0·22 (−1·65 to 1·21) in favour of SILC (P = 0·77); there was significant heterogeneity between the studies (χ2 = 136·51, 2 d.f., I2 = 99 per cent). The funnel plot was symmetrical (not shown). Subgroup analysis of postoperative late pain after SILC with or without use of the multiport device was not possible because of the paucity of available data.

Abdominal pain intensity measured on a ten-point scale

In four trials pain was assessed at different time points using a ten-point pain scale14–16, 34 and for this reason the data were not pooled in meta-analysis. The raw data on pain assessment reported in each of these studies are shown in Table 5.

Table 5. Postoperative pain measured on a ten-point intensity scale
 Mean pain score
ReferencePostop. pain*DischargeDay of surgeryPOD 1POD 2POD 3POD 5POD 7POD 14POD 30First clinical visit
  • Pain intensity was measured on a ten-point visual analogue scale.

  • *

    Time of pain assessment not specified. POD, postoperative day; SILC, single-incision laparoscopic cholecystectomy; LC, conventional laparoscopic cholecystectomy; NS, not significant.

Lirici et al.14           
 SILC  3·752·551·35    0·6 
 LC  3·152·250·1    0·3 
 P  0·041NSNS    NS 
Ma et al.15           
 SILC 2·7        1·8
 LC 1·8        1·8
 P 0·06        0·52
Phillips et al.34           
 SILC4·8  4·9 4·03·22·81·61·6 
 LC4·5  4·4 3·32·52·31·61·3 
 P0·350  0·120 0·0260·0090·0660·4350·028 
Adverse events

There were no deaths reported in any of the included studies. All studies investigated adverse events. The pooled OR for adverse events was 1·14 (0·69 to 1·91) in favour of LC (P = 0·61), with no heterogeneity between the studies (χ2 = 5·41, 10 d.f., I2 = 0 per cent) (Fig. 8). The funnel plot was symmetrical (not shown). The types and numbers of considered adverse events are shown in Table 6.

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Figure 8. Pooled estimate of rate of adverse events after single-incision laparoscopic cholecystectomy (SILC) versus conventional laparoscopic cholecystectomy (LC). A Mantel–Haenszel fixed-effects model was used for meta-analysis. Odds ratios are shown with 95 per cent confidence intervals

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Table 6. Adverse events
 SILC (n = 481)LC (n = 442)
  1. Values in parentheses are percentages. SILC, single-incision laparoscopic cholecystectomy; LC, conventional laparoscopic cholecystectomy.

Bile leak2 (0·4)3 (0·7)
Choledocholithiasis2 (0·4)1 (0·2)
Wound infection and hernia15 (3·1)9 (2·0)
Wound bleeding, haematoma and seroma5 (1·0)8 (1·8)
Gallbladder perforation9 (1·9)6 (1·3)
Urinary retention0 (0)1 (0·2)
Intra-abdominal abscess2 (0·4)0 (0)
Postoperative ileus0 (0)1 (0·2)
Total adverse events35 (7·3)29 (6·6)
Wound infection

It was possible to extract the number of wound infections in each treatment group from all of the included studies. Nine wound infections were reported in the SILC group and eight in the LC group. The pooled OR was 1·03 (0·40 to 2·63) in favour of LC (P = 0·96). There was no heterogeneity between the studies (χ2 = 1·65, 4 d.f., I2 = 0 per cent). The funnel plot was symmetrical (not shown).

Port-site hernia

It was possible to extract the rate of postoperative port site hernia from all of the included studies. The follow-up period was not specified in five trials12, 15, 19–20, 33; in the other trials it was 1 month14, 21, 32, a maximum of 12 months34, a median of 9·4 and 11·6 months in the SILC and LC groups respectively35, a mean of 38 months17, and a mean of 29·9 and 22·7 weeks in the SILC and LC groups respectively22. Six port-site hernias were reported in the SILC group and only one in the LC group. The pooled OR was 2·99 (0·60 to 14·80) in favour of LC (P = 0·18), with no significant heterogeneity between the studies (χ2 = 0·01, 2 d.f., I2 = 0 per cent). The funnel plot was symmetrical (not shown).

Cosmetic result

Eight studies assessed cosmetic outcomes12, 14–16, 21, 33–35. Only two reported data on the Body Image Scale questionnaire, ranging from 5 (best) to 20 (worst results). Data obtained at different time points (1 and 2 weeks, 1 and 3 months after surgery) were amenable to pooling (Fig. 9)16, 21. Marks and colleagues16 described LC performed using two or three 5-mm ports plus one or two 10- or 12-mm port according to surgeons' personal preferences, whereas Bucher et al.21 used two 5-mm and two 10-mm ports. In both studies single-port devices were used in SILC procedures. There was no difference between SILC and LC at 1 week after surgery (pooled WMD − 0·92, − 3·07 to 1·24; P = 0·40), and there was significant heterogeneity between the two studies (χ2 = 51·73, 1 d.f., I2 = 98 per cent) (Fig. 9). On pooling the data, statistically significant differences were found in favour of SILC after 2 weeks (WMD − 1·40, − 2·67 to − 0·12; P = 0·03) (χ2 = 13·26, 1 d.f., I2 = 92 per cent) and 1 month (WMD − 1·00, − 1·08 to − 0·92; P < 0·001) (χ2 = 0·17, 1 d.f., I2 = 0 per cent) (Fig. 9). The overall WMD, based on a total of 694 observations on the Body Image Scale at several time points, was − 0·97 (−1·51 to − 0·43) in favour of SILC (P < 0·001), but there was significant heterogeneity (χ2 = 316·63, 6 d.f., I2 = 98 per cent). The funnel plot was symmetrical (not shown).

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Figure 9. Pooled estimate of cosmetic outcome a 1 week, b 2 weeks, c 1 month, d 3 months and e overall after single-incision laparoscopic cholecystectomy (SILC) versus conventional laparoscopic cholecystectomy (LC). An inverse variance random-effects model was used for meta-analysis. *Values are mean(s.d.) scores on the Body Image Scale ranging from 5 (best) to 20 (worst). Weighted mean differences (WMDs) are shown with 95 per cent confidence intervals

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Only Phillips and colleagues34 reported data on a Cosmesis score, ranging from 3 (worst) to 24 (best) at different times after surgery (1 and 2 weeks, 1 and 3 months, 1 year), that were amenable to pooling. In this study LCs were performed using two or three 5-mm ports and one or two 10- or 12-mm ports; all SILCs were performed using a single-port device. The overall WMD, based on a total of 791 observations, was − 2·46 (−2·95 to − 1·97) in favour of SILC (P < 0·001), with no heterogeneity (χ2 = 2·37, 4 d.f., I2 = 0 per cent) (Fig. 10). The funnel plot was symmetrical (not shown).

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Figure 10. Pooled estimate of cosmesis score a 1 week, b 2 weeks, c 1 month, d 3 months, e 1 year and f overall after single-incision laparoscopic cholecystectomy (SILC) versus conventional laparoscopic cholecystectomy (LC). An inverse variance fixed-effects model was used for meta-analysis. *Values are mean(s.d.) cosmesis scores on a scale ranging from 3 (worst) to 24 (best). Mean values at each time point have been multiplied by − 1 in order to invert the direction of the scale. Weighted mean differences (WMDs) are shown with 95 per cent confidence intervals

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In six trials the cosmetic outcome was assessed by means of additional cosmetic evaluation items or a questionnaire12, 14, 15, 33–35, but pooled analysis was impossible owing to the lack of homogeneity in items and time points studied. In the study by Lai and colleagues33 each incision was rated by the patients on a scale from 1 (worst) to 10 (best) at 3 months after surgery. The cosmesis score was significantly higher in the SILC group than in the LC group (median 7 versus 6; P = 0·023). Aprea and co-workers12 registered a wound satisfaction score (very dissatisfied, 1; dissatisfied, 2; acceptable, 3; satisfied, 4; very satisfied, 5) on day 7 after surgery. There was a statistically significant difference between the two groups in favour of SILC (mean 3·5 versus 4·9; P < 0·05). Lirici et al.14 evaluated the cosmetic results using a VAS system ranging from 0 per cent (worst result) to 100 per cent (best result). There were no significant differences in VAS scores on the day of discharge (mean 75 per cent in LC versus 83·5 per cent in SILC group). However, cosmetic satisfaction was significantly higher in the SILC group after 1 month (mean 95·5 per cent versus 86 per cent in the LC group; P = 0·025). Ma and colleagues15 measured overall patient satisfaction using a ten-point scale at the first outpatient follow-up appointment (2–3 weeks after surgery); this was reported to be 8·9 for SILC versus 9·2 for LC (P = 0·59), with cosmetic satisfaction scores of 9·3 and 8·9 respectively (P = 0·41). In the trial by Phillips and co-workers34 SILC produced better cosmetic outcomes, evaluated using the Photo Series Questionnaire at 1 week, 2 weeks, 1 month, 3 months (all P < 0·001) and 1 year (P = 0·002). Using a ten-point questionnaire (0, worst; 10, best), Zheng et al.35 found that mean satisfaction scores relating to the operation were 8·9 in the SILC group and 8·1 in the LC group 1 month after surgery (P = 0·012).

Quality of life

Only four studies reported on QoL outcomes14, 15, 21, 34, but heterogeneity in items measured and time points used did not allow pooled analysis. Bucher and colleagues21 reported that the median summarized postoperative QoL score in the Short Form 12 (SF-12®; QualityMetric, Lincoln, Rhode Island, USA) was 40 points in the SILC group versus 35 in the LC group (P = 0·02). Lirici and colleagues14 used the SF-36® questionnaire to compare QoL in the SILC and LC groups at 30 days' follow-up. A statistically significant different was found only for the ‘emotional role’ items (mean 80·05 versus 68·33 respectively; P = 0·001). Ma et al.15 measured QoL during the first postoperative follow-up appointment by patient-reported SF-36® questionnaire and reported no significant difference between SILC and LC groups. Phillips et al.34 compared SF-8 QoL questionnaire scores between groups; they found a statistically significant difference on postoperative day 3 after surgery (P = 0·02) in favour of SILC, but not on day 1 (P = 0·43), day 5 (P = 0·13) or at 1 week (P = 0·80) after surgery. SF-12® questionnaires were administered 2 weeks and 1 month after surgery, with results significantly in favour of SILC only at 2 weeks (P = 0·03).

Discussion

  1. Top of page
  2. Abstract
  3. Introduction
  4. Methods
  5. Results
  6. Discussion
  7. Disclosure
  8. References
  9. Supporting Information

The recently published meta-analyses by Markar and colleagues11 and Garg et al.4 comparing SILC with LC did not evaluate the feasibility of SILC. The present meta-analysis showed a procedural failure rate for SILC ranging from 0 to 67 per cent, significantly higher than for LC. This finding is in contrast with the median procedure failure rate of 2 per cent in a review of the literature based only on non-randomized data and that do not consider port addiction as a procedure failure36.

The duration of operation was significantly longer for the SILC approach. In a study of surgical training for SILC, Qiu and colleagues37 found that surgeons approach an acceptable level of expertise only after having performed at least 20 procedures, and only after the 40th procedure do they reach a well developed phase of experience. On the other hand, others have suggested that five38 or ten39 SILC procedures represents a sufficient learning curve for experienced laparoscopic surgeons. Some of the surgeons who took part in the trials included in this analysis had modest experience, if any, in the SILC approach. This heterogeneity largely explains the range of operating times and seriously limits an evaluation of the feasibility of SILC. In a separate analysis of procedures carried out using non-conventional instruments, it was found that the procedure failure rate was significantly higher in the SILC group. Perhaps the use of innovative non-traditional instruments by inexpert surgeons actually impairs operative technique.

A remarkable heterogeneity of technical aspects and laparoscopic instruments used is evident. Only three of the included RCTs did not use a single-port device but inserted instruments separately through different fascial incisions, all passing through the same skin incision17, 19, 32. A comprehensive evaluation of SILC technique would require a cost-effectiveness comparison with the conventional laparoscopic techniques. Only one study reported the costs of the two types of procedure21, so it was not possible to perform this analysis. Operating costs, calculated on the basis of disposables used and operating room charges including salaries, were higher for SILC procedures (an additional US $400 per procedure)21.

The mean intraoperative blood loss was significantly higher in the SILC group, although the effect size was small. The authors believe that a number of factors could have contributed to this result. In SILC the loss of triangulation makes the use of instruments for suction/irrigation and diathermy extremely difficult, resulting in less accurate haemostasis than with LC. A less sharp image in SILC can lead to underestimation of the presence of bleeding, and the ergonomic limitation to the versatility of the instruments can lead to a less smooth dissection, especially during detachment of the gallbladder from its hepatic bed when most subtle bleeds occur. It is also important to note that in most of the included studies the SILC procedures were performed during the surgeon's learning curve.

There was no difference in hospital stay between the two approaches, as would be predicted as both are minimally invasive. The overall adverse event rates were comparable (SILC 7·3 per cent, LC 6·6 per cent). These data were consistent with the results reviewed by Allemann and colleagues36, who estimated a 5·4 per cent global complication rate after SILC. In the present analysis the bile leakage rate was 0·4 per cent in the SILC and 0·7 per cent in the LC group. No common bile duct injuries were reported in either group. Although major complications have been reported after SILC40, a previous meta-analysis11 suggested that SILC is a safe procedure. The wide confidence interval found in the present analysis of SILC safety confirms the need for adequately powered randomized trials in the evaluation of SILC safety.

No significant differences were found in postoperative port site hernia rate, but follow-up times were short. Moreover, several studies did not report on the technique and material used for closure12, 14, 15, 19, 33, 34.

Although postoperative pain has not been a major concern since the introduction of routine LC, supporters of SILC advocate the hypothesis that reduction in the number of incisions may result in a lower postoperative pain. On the other hand, some authors believe that SILC increases postoperative pain because of the additional stress on the port incision necessary to allow triangulation of the instruments and exposure, or owing to a longer incision at the port site34. Previous meta-analyses4, 11 showed no difference in pain on the day after surgery between the two approaches. In the present meta-analysis no differences in postoperative pain were found up to 30 days after surgery. Nevertheless, the large confidence interval again limited the clinical value of the statistical findings. Notably, several trials used more than one 10-mm port for LC.

A previous meta-analysis found a significant advantage for SILC versus LC in terms of cosmesis4. The present study compared cosmetic outcomes in the two groups, considering homogeneous cosmetic evaluation scales (Cosmesis score and Body Image Scale) at predefined time points. Cosmetic satisfaction was found to be greater in patients who had undergone SILC, but these results should be considered with caution as the analyses included only three trials16, 21, 34 and the results require confirmation in further randomized trials. Furthermore, patients were blinded to the treatment received in none of studies included in the meta-analysis of postoperative pain and in only two that studied cosmetic outcomes16, 34, exposing the analysis to performance bias.

Disclosure

  1. Top of page
  2. Abstract
  3. Introduction
  4. Methods
  5. Results
  6. Discussion
  7. Disclosure
  8. References
  9. Supporting Information

The authors declare no conflict of interest

Supporting information

Additional supporting information may be found in the online version of this article:

Appendix S1 Characteristics of included trials - inclusion and exclusion criteria

References

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  2. Abstract
  3. Introduction
  4. Methods
  5. Results
  6. Discussion
  7. Disclosure
  8. References
  9. Supporting Information
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Supporting Information

  1. Top of page
  2. Abstract
  3. Introduction
  4. Methods
  5. Results
  6. Discussion
  7. Disclosure
  8. References
  9. Supporting Information
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