Prophylactic Pelvic Drainage of Extraperitoneal Rectal Anastomoses: A Friend or a Foe?

The role of prophylactic drain placement after rectal resections with extraperitoneal anastomosis remains unclear and controversial. A systematic search was conducted using the PubMed database for randomized controlled trials (RCTs) and non-randomized controlled clinical trials (CCTs) comparing clinical outcomes of patients with drained and undrained extraperitoneal colorectal or coloanal anastomoses. The primary outcome was anastomotic leakage (AL), whereas secondary outcomes included the impact of drainage on mortality, postoperative bowel obstruction, wound infection, reoperation rate, and length of hospital stay.  Three RCTs and four CCTs that met the inclusion criteria were identified. Two RCTs were judged at a low risk of bias and one at unclear risk. Among CCTs, three were considered to be of fair and one of good methodological quality. Significant discrepancies were encountered among these studies in terms of study design, definition of endpoints, population characteristics, and several technical aspects that render patients' grouping for conclusion extraction at least demanding, if not unsafe.  In conclusion, there is not sufficient evidence to support routine drainage after rectal surgery with extraperitoneal anastomosis, although drain insertion does not appear to increase postoperative morbidity.