COMPASS (management of COMPlicAted intra-abdominal collectionS after colorectal Surgery) was an international, matched prospective cohort study aiming to describe the international variation in practice regarding intraperitoneal drain placement in elective colorectal surgery and the associated effects on postoperative outcomes. The study was designed and led by the student and trainee-led collaborative, EuroSurg with support from STARSurg and other organisations in dissemination, data collection and analysis.

Peritoneal drains are considered to be vital in the prevention and early detection of anastomotic leak following elective colorectal surgery, providing therapeutic benefit. Recently, evidence has shown that these drain can actually stimulate serous fluid production and therefore increase the risk of surgical-site infections and adhesions, resulting in worse mobility, postoperative pain, discomfort and anxiety. This has led to the enhanced recovery after surgery (ERAS) guidelines recommending against the use of routine drains. Nevertheless, their prophylactic use remains widespread.

COMPASS aimed to address the following key questions:

• How many patients get a prophylactic drain in modern practice?
• Which patients get drains, and, when is it safe to remove them?
• Can a drain allow for earlier detection of collections?
• What is the incidence of drain-related complications?

The study analysed 1,805 patients, 51.9% of which received a drain. 67.8% of drains were placed prophylactically and 32.2% were placed for a specific indication. The most common indications were excessive intraoperative fluid loss (14.8%), contamination or dirty surgery (10%), excess intraoperative blood loss (6.8%), poor anastomotic vascularisation (3.5%) and positive air leak test (0.6%).

The study also confirmed previous findings which showed no clinical benefit for routine drain placement, with no difference in the odds of detection of postoperative major complications and intraperitoneal collections. In addition, drain placement did not alter the time of diagnosis of intraperitoneal collections.