Prophylactic Abdominal Drainage after Bariatric Surgery: A Narrative Review of the Evidence and Practical Considerations for Drain Selection

Surgeons have long placed an intra-abdominal drain after sleeve gastrectomy and gastric bypass to detect staple-line leak or bleeding early and to control a leak without reoperation. Enhanced-recovery pathways and large registry analyses have challenged this practice. This review summarises the evidence on whether, when and how to drain after metabolic and bariatric surgery. Four PubMed/MEDLINE searches were run through the NCBI E-utilities on 6 November 2026 (publication dates 1 January 1990 to 31 October 2026), supplemented by targeted look-ups. Records were screened in two stages; outcomes were extracted as reported, without re-pooling. Every reference was checked against PubMed and Crossref (DataCite for the one Zenodo record). The searches returned 2345 records (2169 unique); 81 reports were included. Only small randomised trials compared drain with no drain (66 and 84 patients after gastric bypass); both found more pain with drains and no detectable benefit. Registry analyses of 142,631 to 526,723 patients associated drains with higher adjusted odds of leak and reoperation and, in the most recent analyses, of organ-space infection and prolonged stay; these associations are probably confounded by selective drain use in higher-risk cases. Reported sensitivity of drains for leak ranged from 0% to 94.1%. Many leaks present after the usual drain-removal window. Drain amylase, judged against study-specific cut-offs, had high sensitivity and specificity in three single-centre series. The 2021 ERAS Society guideline and Canadian and Italian consensus statements advise against routine drainage; the 2016 ERAS guideline judged it probably unnecessary. Current evidence does not support routine prophylactic drainage after primary bariatric surgery. Selective use in revisional operations, difficult anastomoses or recognised bleeding risk is common practice but remains unproven. If a drain is used, its type, position and removal should be planned.