Extracellular Matrix Hydrogel Reduces Anastomotic Leaks in a Rodent Model of Rectal Anastomosis.

Introduction: Anastomotic leaks remain a significant source of morbidity following rectal resections. Despite advances in technique, the incidence of leaks remains high, often necessitating temporary fecal diversion which carries its own risks and requires additional surgery for restoration of intestinal continuity. Reducing leak rates could minimize the need for prophylactic diversion. Extracellular matrix (ECM)-based surgical devices have shown potential to support gastrointestinal healing. Urinary bladder matrix (UBM), a versatile, acellular ECM material that promotes constructive tissue remodeling, has not been extensively studied in colorectal anastomoses. A lack of reliable small animal models has limited progress in this field.

Methods: A reproducible rat model of low rectal anastomosis was developed to evaluate ECM-based interventions. Female Sprague-Dawley rats underwent standardized distal colonic resection and sutured anastomosis below the peritoneal reflection. Rats were randomized to receive no adjunct, UBM extraluminal wraps, or UBM hydrogel applied directly to the anastomosis. Healing was assessed using a multimodal evaluation strategy.

Results: Control animals demonstrated a 46% anastomotic leak rate, while UBM hydrogel treatment significantly reduced leak rates to 8%. Extraluminal wraps did not confer a protective effect. Rats treated with hydrogel also exhibited fewer perianastomotic adhesions. Histological analysis showed improved composite healing scores in the hydrogel group.

Conclusions: This reliable small animal model provides a valuable platform for testing surgical adjuncts. UBM hydrogel shows promise in reducing rectal anastomotic leak rates through both mechanical support and biochemical modulation of healing. This model enables further investigation into anastomotic healing mechanisms and potential therapeutic strategies.