Ileocolic intussusception in an adult

Clinical History

The patient presenting with acute onset of severe right-sided abdominal pain and a palpable right iliac fossa mass.

Imaging Findings

The patient presented with acute onset of severe right-sided abdominal pain associated with nausea, vomiting and one episode of diarrhoea. This was preceded by similar episodes of pain over a 3-week period. On examination the patient had a palpable right iliac fossa mass. Plain film of the abdomen showed a paucity of bowel gas in the right side of the abdomen with an impression of a soft tissue mass in this area. Abdominal ultrasound showed an abnormal loop of bowel in the right iliac fossa with a "pseudokidney" appearance suggestive of an intussusception. CT scanning confirmed an ileocolic intussusception and also showed proximal small bowel dilatation and free intraperitoneal fluid. The intussusception was surgically resected and a polyp was found at the lead point.

Discussion

Intussusception is common in children, but remains a rare clinical entity in adults. In adults the condition is associated with underlying pathology in over 80% of cases. Causes include benign and malignant tumours, lipomas, polyps, Meckle's diverticulum and adhesions. Patients typically present with recurrent, non-specific abdominal pain, although acute presentations can occur as in this case. Ileoileal are more common than ileocolic intussusceptions.

Plain film findings are often not helpful and include soft tissue mass and small bowel obstruction. Ultrasound or CT examination is usually required for diagnosis. Ultrasound has been shown to have typical appearances in this condition. On transverse sections a "doughnut" or "bull's eye" sign is often seen and on longitudinal sections a "pseudokidney" or "hayfork" sign is typical. Characteristic CT patterns have been observed including an inhomogenous soft tissue mass, which may be target- or sausage-shaped. Alternating layers of high and low attenuation or a fatty component can also be seen on CT. The fascial planes around the target mass are typically retained.

Bowel obstruction is not common and the presence of intramural air is indicative of vascular compromise of the intussuscepting bowel. Malignant lesions are the most common cause of intussusception in the adult, so early diagnosis and prompt intervention is essential. Malignancy is more likely in colonic intussusceptions compared with those involving small bowel alone. Surgical resection is advocated, with or without prior reduction. In small intestine intussusceptions primary malignancy is uncommon, so initial reduction followed by limited resection is the treatment of choice.

Intussusception is an unusual entity in the adult with characteristic sonographic and CT appearances. As a large proportion of these patients have an underlying malignancy prompt diagnosis and treatment is essential.

Differential Diagnosis List

Final Diagnosis

Ileocolic intussusception secondary to an intestinal polyp

URL:	https://www.eurorad.org/case/1612
DOI:	10.1594/EURORAD/CASE.1612
ISSN:	1563-4086