Rather than meerely wait for bowel sounds to return after patients undergo surgery, we can try to get the gut working again sooner. An active approach might shorten the duration of postoperative ileus, allow patients to go home from the hospital sooner, and improve their outcomes.
In the pages that follow, we review the pathophysiology, diagnosis, and current therapies to alter the course of postoperative ileus.
ILEUS CAN AFFECT THE STOMACH OR SMALL OR LARGE INTESTINES
Ileus is the absence of intestinal peristalsis without mechanical obstruction; postoperative ileus refers to the time after surgery before coordinated electromotor bowel function resumes.
Gastroparesis refers to abnormal gastric motility leading to impaired gastric emptying. This disabling, potentially chronic condition is associated with certain medical conditions such as diabetes, but can also occur after some surgical procedures, as we will discuss. It has been estimated to affect approximately 4% of the adult population, with a strong female predilection.1 Postoperative gastroparesis is probably most common after pancreaticoduodenectomy, in which it occurs in up to 57% of patients.2 Consensus guidelines for grading the severity of gastroparesis have been devised to help standardize the reporting of outcomes.2
Acute colonic pseudo-obstruction (colonic ileus) is often seen in elderly hospitalized patients with multiple medical comorbidities. Of note, it often occurs after surgery to parts of the body other than the abdomen, such as after orthopedic procedures. One study documented an incidence of 1.3% after hip replacement surgery and 1.2% after spine procedures.3
The small bowel normally resumes activity several hours after surgery, the stomach 24 to 48 hours after surgery, and the colon 3 to 5 days after surgery.4 When postoperative ileus persists longer than this, it can be considered pathologic and is sometimes called paralytic ileus.4,5
ILEUS AFFECTS OUTCOMES AND COSTS
Although not usually considered life-threatening, postoperative ileus is harmful for the patient and costly for society.
For the patient, ileus is uncomfortable, leads to nausea and vomiting, delays return to enteral nutrition, and prolongs the stay in the hospital. For many if not most patients undergoing gastrointestinal surgery, return of bowel function is the factor that delays going home. A prolonged hospital stay increases the risk of hospital-acquired infections, deep vein thrombosis, and other conditions.
The economic burden is also considerable. A retrospective review of more than 800,000 patients who underwent surgery in the United States in 2002 found a rate of postoperative ileus of 4.25% according to International Classification of Diseases–Ninth Revision (ICD-9) codes.6 The mean hospital length of stay was 9.3 days in patients with postoperative ileus vs 5.3 days in those without it. The difference in mean total hospital costs was US $6,300 per patient. The costs certainly add up when you consider the number of surgical procedures performed every year.
NEURAL AND CHEMICAL FACTORS
While observing exteriorized bowel in 1872, Goltz7 first noted enhanced spontaneous contractions when the spinal cord was severed at the level of the medulla. Not long after, Bayliss and Starling8 used a device called an “enterograph” to monitor small-bowel activity in vivo in dogs and found that cutting the splanchnic nerves led to vigorous bowel contraction after laparotomy. These early observations formed the foundation of our understanding of postoperative ileus and some of its possible causes.
Normal bowel contractility is influenced by a host of neural and chemical factors, the relative contributions of which vary depending on the segment of bowel.
The migrating motor complex is the basal level of activity in the bowel in the fasting state, serving a “housekeeping” function.9 It has four phases, consisting of escalating electrical and contractile activity punctuated by periods of quiescence. The resumption of this motor complex after surgery is responsible for recovery from postoperative ileus.