The most common cause of ileus is
Other causes include
Metabolic disturbances (eg, hypokalemia)
Drugs (eg, opioids, anticholinergics, sometimes calcium channel blockers)
Gastric and colonic motility disturbances after abdominal surgery are common. The small bowel is typically least affected, with motility and absorption returning to normal within hours after surgery. Stomach emptying is usually impaired for about 24 hours or more. The colon is often most affected and may remain inactive for 48 to 72 hours or more.
Symptoms and signs of ileus include abdominal distention, nausea, vomiting, and vague discomfort. Pain rarely has the classic colicky pattern present in mechanical bowel obstruction. There may be obstipation or passage of slight amounts of watery stool. Auscultation reveals a silent abdomen or minimal peristalsis. The abdomen is not tender unless the underlying cause is inflammatory.
The most essential task is to distinguish ileus from intestinal obstruction. In both conditions, x-rays show gaseous distention of isolated segments of intestine. In postoperative ileus, however, gas may accumulate more in the colon than in the small bowel. Postoperative accumulation of gas in the small bowel often implies development of a complication (eg, obstruction, peritonitis). In other types of ileus, x-ray findings are similar to obstruction; differentiation can be difficult unless clinical features clearly favor one or the other. A contrast-enhanced CT may help differentiate between the two and suggest an underlying cause of the ileus.
Treatment of ileus involves continuous nasogastric suction, nothing by mouth, IV fluids and electrolytes, a minimal amount of sedatives, and avoidance of opioids and anticholinergic drugs. Maintaining an adequate serum potassium level (> 4 mEq/L [> 4.00 mmol/L]) is especially important. Ileus persisting > 1 week probably has a mechanical obstructive cause, and laparotomy should be considered.
Sometimes colonic ileus can be relieved by colonoscopic decompression; rarely, cecostomy is required. Colonoscopic decompression is helpful in treating pseudo-obstruction (Ogilvie syndrome), which consists of apparent obstruction at the splenic flexure, although no cause can be found by contrast enema or colonoscopy for the failure of gas and feces to pass this point. Some clinicians use IV neostigmine (which requires cardiac monitoring) to treat Ogilvie syndrome.