The impact of defunctioning ileostomies on postoperative kidney function in rectal cancer surgery

Aim To investigate short‐ and long‐term kidney injury incidence in patients undergoing low anterior resection for rectal cancer, comparing those with and without a defunctioning ileostomy. Method We identified all Swedish rectal cancer patients ≤80 years old, with ASA fitness grade ≤III and tumour height ≤12 cm from the anal verge, who underwent anterior resection between 2007 and 2021 using CRCBaSe, a nationwide registry linkage. Patients who received a defunctioning ileostomy during surgery were compared with those who did not. Outcomes included chronic kidney failure, chronic kidney disease, acute kidney injury, and dehydration. Cox proportional hazards models were fitted for each outcome, using overlap weights derived from propensity scores for receiving a defunctioning ileostomy. Stoma reversal impact and mediation by anastomotic leakage were also examined. Results Among 5286 patients, 4623 (87%) received a defunctioning ileostomy and 663 (13%) did not. A defunctioning ileostomy was not significantly associated with chronic kidney failure (HR 1.68, 95% CI: 0.19–15.16) or chronic kidney disease (HR 1.65, 95% CI: 0.91–2.98) but increased risks of acute kidney injury (HR 3.01, 95% CI: 1.61–5.64) and dehydration (HR 4.02, 95% CI: 2.33–6.94). Risks declined after stoma reversal. Stomas reduced anastomotic leakage with negligible mediation effects on short‐term kidney damage. Conclusion A defunctioning ileostomy after low anterior resection increases the risks of acute kidney injury and dehydration but not chronic kidney failure or chronic kidney disease. These risks decrease following stoma reversal, highlighting the need for careful perioperative management.