Colorectal Anastomotic Leakage: A new, Validated Rat Model

Background: Anastomotic leakage (AL) remains an important complication after colorectal surgery. Experimental research aims to find a solution to overcome this serious complication; however, no validated AL model exists in the rat. This study was designed to develop a feasible new, reproducible AL model for use in colorectal anastomotic research. Methods: Forty-four male Wistar rats, randomly divided into 4 groups, underwent a midline laparotomy and transection of the proximal colon. An anastomosis was created with 3, 4, 5, or 12 (control) sutures. After 7 days, the rats were euthanized and scored for the presence of AL. The secondary outcomes were anastomotic bursting pressure (ABP), histological evaluation, and maturation of collagen. After the initial experiment, the AL model was reproduced in an external academic center to ensure reproducibility. Results: AL occurred in 68.8% of rats treated with an insufficient anastomosis, compared to 10% of the control group (P=0.005). AL rates were highest (81.8%) in the 3-suture group and lowest (50%) when 5 sutures were used. The experiment with 4 sutures was reproduced at an external academic center and showed similar AL rates as in our center (72.7% vs. 63.6%). Conclusions: Our rat model for inducing AL by creating an anastomosis using an insufficient number of sutures is feasible and reproducible. When combining all outcome measures, the AL model for colorectal leakage using 4 sutures is the most suitable for use in future research.