Etiology of Ileus
The most common cause of ileus is
Other causes include
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Intraperitoneal or retroperitoneal inflammation (eg, appendicitis Appendicitis Appendicitis is acute inflammation of the vermiform appendix, typically resulting in abdominal pain, anorexia, and abdominal tenderness. Diagnosis is clinical, often supplemented by CT or ultrasonography... read more
, diverticulitis Colonic Diverticulitis Diverticulitis is inflammation with or without infection of a diverticulum, which can result in phlegmon of the bowel wall, peritonitis, perforation, fistula, or abscess. The primary symptom... read more 
, perforated duodenal ulcer Peptic Ulcer Disease A peptic ulcer is an erosion in a segment of the gastrointestinal mucosa, typically in the stomach (gastric ulcer) or the first few centimeters of the duodenum (duodenal ulcer), that penetrates... read more 
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Retroperitoneal or intra-abdominal hematomas (eg, from ruptured abdominal aortic aneurysm Abdominal Aortic Aneurysms (AAA) Abdominal aortic diameter ≥ 3 cm typically constitutes an abdominal aortic aneurysm. The cause is multifactorial, but atherosclerosis is often involved. Most aneurysms grow slowly (~10%/year)... read more
, blunt abdominal trauma Overview of Abdominal Trauma The abdomen can be injured in many types of trauma; injury may be confined to the abdomen or be accompanied by severe, multisystem trauma. The nature and severity of abdominal injuries vary... read more ) -
Drugs (eg, opioids, anticholinergics, sometimes calcium channel blockers)
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Sometimes renal or thoracic disease (eg, lower rib fractures Rib Fracture One or more ribs can be fractured due to blunt chest injury. (See also Overview of Thoracic Trauma.) This x-ray of the chest shows multiple fractures to the right ribs (seen on left). Typically... read more
, lower lobe pneumonias Community-Acquired Pneumonia Community-acquired pneumonia is defined as pneumonia that is acquired outside the hospital. The most commonly identified pathogens are Streptococcus pneumoniae, Haemophilus influenzae, atypical... read more 
, myocardial infarction Acute Myocardial Infarction (MI) Acute myocardial infarction is myocardial necrosis resulting from acute obstruction of a coronary artery. Symptoms include chest discomfort with or without dyspnea, nausea, and diaphoresis.... read more 
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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
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 Intestinal Obstruction Intestinal obstruction is significant mechanical impairment or complete arrest of the passage of contents through the intestine due to pathology that causes blockage of the bowel. Symptoms include... read more 
. 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.
Diagnosis of Ileus
The most essential task is to distinguish ileus from intestinal obstruction Diagnosis Intestinal obstruction is significant mechanical impairment or complete arrest of the passage of contents through the intestine due to pathology that causes blockage of the bowel. Symptoms include... read more . 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 Intestinal Obstruction Intestinal obstruction is significant mechanical impairment or complete arrest of the passage of contents through the intestine due to pathology that causes blockage of the bowel. Symptoms include... read more , peritonitis Peritonitis Abdominal pain is common and often inconsequential. Acute and severe abdominal pain, however, is almost always a symptom of intra-abdominal disease. It may be the sole indicator of the need... read more ). 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
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.
