Magnitude of abdominal incision affects the duration of postoperative ileus in rats

Background: The pathogenesis of reduced postoperative ileus (POI) in laparoscopic gastrointestinal (GI) surgery still remains controversial. The aim of this study was to investigate the effect of surgical incision on postoperative ileus. Methods: The effects of length, depth, and site of the incision on GI transit were compared using the geometric center of Cr-51 in rats. The Inhibitory mechanism of abdominal incision on GI transit also was studied. Results: The findings showed that 5 cm of abdominal skin and the 5-cm back muscle incision had no significant effect on GI transit. However, the 5-cm abdominal muscle-fascia incision and a 5-cm laparotomy significantly delayed GI transit. Gastrointestinal transit after a 5-cm laparotomy was significantly delayed, as compared with that of a 1-cm laparotomy regardless whether intestinal manipulation was performed or not. Guanethidine and yohimbine, but not propranolol, significantly improved the impaired GI transit after a 5-cm laparotomy. Conclusions: The results suggest that the longer and deeper abdominal incision more profoundly inhibits GI transit. The inhibitory effect of abdominal incision is mediated via the activation of the somatosympathetic reflex and alpha-2 adrenoceptors.