GI Anomalies: Idiopathic Ileal Intussusception

For 2 days, an 81-year-old man had episodes of sharp, intermittent, nonradiating periumbilical pain that lasted about 1 to 5 minutes. He also reported decreased appetite and nausea. He had a percutaneous endoscopic gastrostomy (PEG) tube, which had been changed 6 months earlier. The patient recently had 4 loose stools but no hematochezia or melena. He had dyspnea, which he attributed to chronic obstructive pulmonary disease. He denied vomiting, fevers, chills, and chest pain.

A year earlier, the patient had similar abdominal pain; diverticulitis was diagnosed. He was treated with piperacillin and tazobactam injection and metronidazole. Results of a colonoscopy and esophagogastroduodenoscopy performed during the past year were normal.

Vital signs were stable. Heart sounds were regular without murmurs. Fine, diffuse bilateral rales were noted on auscultation. The abdomen was nondistended, soft with normal active bowel sounds; there was minimal tenderness to palpation diffusely throughout. The PEG tube site was clean, dry, and intact. There was no rebound, guarding, or hepatosplenomegaly. Neurological findings were nonfocal.

The white blood cell count was at the upper limit of normal. Urinalysis showed 10 white blood cells with no leukocyte esterase or nitrites. Results of other laboratory tests, including a basic metabolic panel and liver enzyme levels, were normal.

A CT scan of the abdomen and pelvis with contrast revealed a 2-cm ileo-ileal intussusception in the right abdomen without small-bowel obstruction or visualized mass (A). No free air, ascites, or acute inflammatory changes were identified.

Ileal intussusception is a telescoping of a segment of the bowel into the lumen of adjacent distal bowel. This results when peristalsis carries a lead point, or intussusceptum, downstream.¹

About 80% of cases of intussusception occur in infancy and present by age 2 years. Adults account for about 5% to 10% of all reported cases.2 Intussusceptions can be enteroenteric, colocolic, or enterocolic. In adults, they are most commonly ileo-ileal.²

About 54% to 65% of cases are caused by underlying malignancy, including primary bowel carcinomas, polyps, leiomyomas, lymphomas, lipomas, and rarely metastatic disease.2 Other causes include Meckel diverticulum, adhesions from previous surgery, hypertrophied Peyer patches secondary to infection, inflammatory bowel disease, hemangiomas, foreign bodies, endometriosis, parasitic infestations, adenovirus and rotavirus infections, celiac disease, and trauma.3 Intussusceptions that involve the small bowel are usually associated with benign pathology, whereas those that involve the colon are more likely to have a malignant lesion.³ Although a cause is identified in almost 90% of affected adults,² this patient’s lesion was idiopathic.

Adults usually present with intermittent colicky abdominal pain, nausea, hematochezia, and vomiting. Abdominal imaging confirms the diagnosis. Abdominal radiographs are not useful unless there is perforation or significant obstruction, which is rare in adults (less than 1% of all cases). Axial CT scans show the classic target sign of bowel within bowel (B, arrow). Barium studies show a coiled-spring appearance from the trapping of contrast between the portions of bowel.¹

Management involves bowel rest and attempted reduction of enteroenteric lesions, although the use of reduction as a first-line treatment in adults has been debated. Because malignant neoplasms cause most adult intussusceptions, surgery is widely advocated as the procedure of choice.

Prognosis depends on the duration of the intussusception, time to diagnosis, and the underlying cause.^2,3 Complications with long-standing intussusception include gangrene, bowel obstruction, perforation, septicemia, and severe vascular compromise.

This patient did well with intravenous fluids and bowel rest. A small-bowel follow-through revealed no evidence of the intussusception on day 4. On day 5, the patient was able to tolerate his full diet through the PEG tube and he was discharged. The condition did not recur.