Abstract: We identified three eligible trials involving a total of 222 participants with 333 groin wounds. Suction drainage was compared with no drainage in all studies. Two studies were parallel-group, randomized controlled trials, and one was a split-body, randomized controlled trial. Trial settings were not clearly described. Patients undergoing bypass and endarterectomy procedures were included, but none of the studies provided details on the severity of the underlying arterial disease. We deemed all of the studies to be at a high risk of bias in three or more domains of the 'Risk of bias' assessment and overall the evidence was of very low quality. Two out of three studies had unit of analysis errors (with multiple wounds within patients analysed as independent) and it was not possible to judge the appropriateness of the analysis of the third. Meta-analysis was not appropriate, firstly because of clinical heterogeneity, and secondly because we were not able to adjust for the analysis errors in the individual trials. One trial yielded data on surgical site infections (SSI; the primary outcome of the review): there was no clear difference between drained and non-drained wounds for SSI (risk ratio 1.33; 95% confidence interval 0.30 to 5.94; 50 participants with bilateral groin wounds; very low quality evidence). It was not possible to evaluate any other outcomes from this trial. The results from the other two studies are unreliable because of analysis errors and reporting omissions. The data upon which to base practice in this area are limited and prone to biases. Complete uncertainty remains regarding the potential benefits and harms associated with the use of wound drains in lower limb arterial surgery due to the small number of completed studies and weaknesses in their design and conduct. Higher quality evidence is needed to inform clinical decision making. To our knowledge, no trials on this topic are currently active.

Plain-language summary: In June 2016 we searched for randomised controlled trials (RCTs) involving the use of drains after leg artery surgery. We identified three eligible trials involving 333 wounds in 222 patients, mainly aged over 65, who had leg artery surgery. Both men and women were included and all of the wounds were in the groin area as part of bypass and endarterectomy operations to improve blood flow. The studies involved small numbers of patients and were not clearly described. All three studies had serious weaknesses in the way they were designed and performed. The results of the individual studies do not provide reliable information because of weaknesses in study design. It is unclear whether wound drains are beneficial or harmful because we did not find any useful information. None of the studies gave information on whether drains shortened or lengthened the number of days that patients had to spend in hospital. None of the studies gave information about how drains affect patients' quality of life. Overall, we found that the quality of the evidence about the effects of drains after leg artery surgery was very low and we were not able to tell whether drains lead to benefits or harms for patients. Better quality research is needed if patients and healthcare providers think that this is an important topic. This plain language summary is up to date as of 8 June 2016.