Histological study of the left colon of rats after extra-mucosal seromyotomy (continent valves): evaluation of colonic emptying

Abstract

PURPOSE: To elaborate an animal model with the objective of studying the continence of the biological valves surgically performed in the left colon of rats. METHODS: Thirty four rats were operated on and divided into three groups (G). G1 (sham) animals which underwent laparotomy only; G2 (perineal amputation without valves): animals which underwent amputation of the anal sphincter complex combined with a perineal colostomy; G3 (abdominoperineal amputation combined with valves): animals which underwent abdominoperineal amputation combined with three, equidistant and circumferential (360(0)), extra-mucosal seromyotomies, of the descending colon, which were sutured to create biological valves combined with perineal colostomy. Animals were euthanized in the late postoperative period and surgical valves were saved for histopathological study. RESULTS: Surgical procedure provoked intestinal dilation, as well as segmented chambers along the descending colon. Retained fecalomas between the valves and proximal to them were also noted. Six rats died of intestinal obstruction due to fecal impaction at the surgical site. The sequence of events was: stasis, obstruction, distention, perforation, peritonitis and death. Histopathology showed inflammation due to foreign body type reaction around the sutured colon causing partial concentric stenosis, capable of interfering normal mechanical activity of the distal colon. This process resulted in retardation of the intestinal transit. CONCLUSION: Extra-mucosal seromyotomies, with seromuscular suture, can be used as an operative procedure capable of causing retardation in the intestinal transit of rats.