Postoperative paralytic ileus refers to obstipation and intolerance of oral intake due to nonmechanical factors that disrupt the normal coordinated propulsive motor activity of the gastrointestinal tract following abdominal or nonabdominal surgery [1-3]. There is general consensus that some degree of postoperative ileus is a normal obligatory and physiologic response to abdominal surgery [4,5]. Physiologic postoperative ileus is generally a benign condition that resolves without serious sequelae. However, when ileus is prolonged, it leads to patient discomfort, dissatisfaction, and prolonged hospitalization, and must be differentiated from mechanical bowel obstruction or other postoperative complications.
The epidemiology, clinical features, and diagnosis of postoperative ileus are reviewed here. Measures to prevent prolonged postoperative ileus are reviewed separately. (See "Measures to prevent prolonged postoperative ileus".)
PHYSIOLOGIC VERSUS PATHOLOGIC POSTOPERATIVE ILEUS
Postoperative ileus refers to obstipation and intolerance of oral intake due to factors that disrupt the normal coordinated propulsive motor activity of the gastrointestinal tract [1,2,4]. The nature of the surgery, intraoperative complications, and medical comorbidities need to be taken into consideration when distinguishing physiologic from pathologic causes of postoperative ileus. Some degree of postoperative ileus is a normal obligatory and physiologic response to abdominal surgery. The physiologic postoperative ileus that typically follows surgery has a benign and self-limited course. However, when ileus is prolonged, it leads to patient discomfort and dissatisfaction, and must be differentiated from other potential complications. However, a lack of consensus on what constitutes a normal physiologic response has hindered the development of a meaningful clinical definition of prolonged (or pathologic) postoperative ileus.
Following abdominal surgery, "normal" physiologic postoperative ileus due to postoperative gut dysmotility is widely reported as lasting 0 to 24 hours in the small intestine, 24 to 48 hours in the stomach, and 48 to 72 hours in the colon [2,6-9]. However, this belief has been challenged; the duration of postoperative gastrointestinal dysmotility appears to be shorter than previously thought. Generally, gastric and small intestinal activity appear to return within hours of surgery, and colonic activity returns by postoperative day two or three [5,10-16]. Although the most affected parts of the intestine are those that have been manipulated during the surgery, there is experimental evidence that inflammation of the intestinal muscle extends from manipulated areas to nonmanipulated parts of the intestinal tract [17,18]. When the expected period of time extends beyond what is acceptable, the patient is diagnosed as having postoperative ileus, provided there are no signs of mechanical intestinal obstruction (see 'Diagnosis' below).
A wide variety of endpoints have been used to measure gut recovery with no consensus as to which one is most clinically meaningful. In randomized trials of patients undergoing major abdominal surgery, time to recovery of gastrointestinal function has been assessed as time to first solid food, and time to either bowel movement or flatus, whichever occurs later [19-21]. Systematic reviews note that when a definition of postoperative ileus is stated, the timeframe is not given or is inconsistent between studies [20,21]. Definitions have included: