Sample size calculation
hernia, hematoma, seroma
RECURRENCE, SURGICAL SITE INFECTION, COMPLICATION, SEROMA, HEMATOMA, COMPLICATIONS
The complication rate in the drainage group was estimated to reach 20%. No prospective study comparing drainage and without drainage was available in the literature when the study was started. Rates of complications were estimated according to a consensus between surgeons participating to the study. We hypothesized that the absence of drainage would decrease the occurrence of either surgical site infection, seroma, hematoma, or early hernia recurrence by 50% within 30 days after surgery. The sample size was calculated with an 80% power; and a significance level with a 