Colonic Electromechanical Abnormalities Underlying Post-operative Ileus: A Systematic and Critical Review.

Post-operative ileus (POI) is an inevitable consequence of major abdominal surgery, and may be prolonged in up to 30% of patients. Ileus is commonly presumed to result from paralysis of the GI tract, though there is little direct evidence to support this view. The aim of this review is to systematically search and critically review the literature investigating post-operative colonic electrical and mechanical activity. MEDLINE and Embase databases were systematically searched for articles investigating post-operative colonic motor or electrical activity in human patients. Nineteen original articles investigating post-operative colonic motor or electrical activity were identified. Most studies have used low-resolution techniques, with intermittent recordings of colonic motility. Numerous studies have shown that colonic electrical and motor activity does not cease routinely following surgery, but is of abnormal character for 3-6 days following laparotomy. One recent high-resolution manometry study identified hyperactive cyclic motor patterns occurring in the distal colon on the first post-operative day. Low-resolution studies have shown colonic slow waves are not inhibited by surgery, and are present even in the immediate post-operative period. Recovery of normal motility appears to occur in a proximal to distal direction and is temporally correlated with the clinical return of bowel function. No studies have investigated motility specifically in prolonged POI. Future studies should use high-resolution techniques to accurately characterise abnormalities in electrical and mechanical function underlying POI, and correlate these changes with clinical recovery of bowel function.