Incidence of incisional hernia in the specimen extraction site for laparoscopic colorectal surgery: systematic review and meta-analysis

Introduction: The incidence of incisional hernia(IH) may be affected by the choice of specimen extraction incision. The objective of this study was to perform a systematic review and meta-analysis comparing the incidence of IH after midline and off-midline incisions in patients undergoing laparoscopic colorectal surgery. Methods: A systematic search was performed according to PRISMA guidelines to identify all comparative studies from January 1991–August 2016 on the incidence of IH after midline and off-midline(transverse or Pfannenstiel) incisions in patients undergoing laparoscopic colorectal surgery. Case series and studies reporting the IH after stoma site extraction, SILS, or NOTES were excluded. The MINORS instrument was used for quality assessment for observational studies. Weighted estimates were calculated using a random-effects model. Results: A total of 17 articles were identified and included for meta-analysis, 16 of which were observational studies and 1 was an RCT. The mean MINORS score for observational studies was 12.9 (SD 3.2, range 7–17). Sample sizes in the midline (mean 185, range 20–995) and off-midline(mean 184, range 20–903) groups were similar. Follow-up ranged from 17.3 to 42 months. The pooled incidence of IH was 10.6% (338/3177) in midline, 3.7% (48/1314) in transverse, and 0.9% (9/956) in Pfannenstiel incisions. IH was significantly higher in the midline compared to off-midline groups (weighted OR 4.1, 95% CI 2.0–8.3, I = 79.7%, p for heterogeneity <0.001). Midline incisions were also at higher risk of IH versus transverse (weighted OR 3.0, 95% CI 1.4–6.7, I = 72.7%, p for heterogeneity <0.001) and Pfannenstiel (weighted OR 8.6, 95% CI 3.0–24.6, I = 43.5%, p for heterogeneity = 0.101) incisions. There was no publication bias according the funnel plot or statistically (Egger’s p = 0.336). Conclusions: Midline incisions for specimen extraction in laparoscopic colorectal surgery are at significantly higher risk of IH compared to off-midline (transverse or Pfannenstiel) incisions, but these data are of poor quality and heterogeneous.