The Effect of Marginal Ischemia on Colonic Anastomotic Leakage: A Rat Model

Background: Anastomotic leakage remains a serious complication of colorectal surgery, often linked to impaired blood supply at the incision site. Objective: To develop and validate a reproducible rat model of colonic anastomotic leakage induced by graded mesocolon ischemia. Methods: Of 144 operated rats, 138 survived surgery and underwent end-to-end colonic anastomosis with five levels of mesocolon ligation (0–2 cm of unilateral mesocolic ischemia). Postoperative outcomes, including anastomotic integrity, abscess formation, and mortality, were assessed on postoperative day 10. Anastomotic bursting pressures were also measured in a subset of animals. Results: Leak rates increased with ischemia severity: 0% in controls, 16.7% at 0.2 cm, 42.6% at 0.4 cm, 95.8% at 1 cm, and 100% at 2 cm (p < 0.0001, trend test). Bursting pressures decreased progressively with increasing anastomotic severity. The 0.4 cm ischemia condition produced a reproducible intermediate leak rate suitable for experimental interventions. Conclusions: This rat model reliably induces graded anastomotic leaks and can serve as a platform for testing strategies to prevent leakage in high-risk colorectal surgery.