Incidence of Incisional Hernia in the Specimen Extraction Site for Laparoscopic Colorectal Surgery: Systematic Review and Meta-analysis

Maria Abou-Khalil, MD, MSc¹, Lawrence Lee, MD, PhD¹, Sender Liberman, MD¹, Marylise Boutros, MD², Gerald M Fried, MD¹, Liane S Feldman, MD¹. ¹McGill University Health Centre, ²Sir Mortimer B Davis Jewish General Hospital

INTRODUCTION: The incidence of incisional hernia(IH) after laparoscopic colorectal surgery has not decreased compared to open surgery. However, IH may be affected by the choice of specimen extraction site(SES) 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 SES incisions in patients undergoing laparoscopic colorectal surgery.

METHODS: A systematic search was performed according to PRISMA guidelines to identify all comparative studies published from 01/1991 to 08/2016 that reported 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 two main comparative groups were midline and off-midline(further subdivided into transverse and Pfannenstiel) SES incisions, with the incidence of IH as the main outcome measure. The MINORS instrument was used for quality assessment for observational studies. Weighted estimates were calculated using a random effects model.

RESULTS: The systematic search identified 946 unique records, of which 54 underwent full-text review. A total of 17 articles were included for quantitative 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. Outcomes for transverse SES incisions were reported in 14 studies(mean N 144, range 7-710) and Pfannenstiel SES incisions in 7 studies(mean N 137, range 6-636). Follow-up was reported in 14 studies and 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. The incidence of IH was significantly higher in the midline compared to off-midline SES groups(weighted OR 4.1, 95%CI2.0-8.3, I2=79.7%, p for heterogeneity<0.001)[Figure 1]. Midline incisions were also at higher risk of IH versus transverse(weighted OR 3.0, 95%CI1.4-6.7, I2=72.7%, p for heterogeneity<0.001) and Pfannenstiel(weighted OR 8.6, 95%CI3.0-24.6, I2=43.5%, p for heterogeneity=0.101) SES incisions. There was no publication bias according the funnel plot or statistically(Egger’s p=0.336).

CONCLUSIONS: Midline incisions for the SES in laparoscopic colorectal surgery are at significantly higher risk of IH compared to off-midline(transverse or Pfannenstiel) incisions, but these data are poor quality and heterogeneous.