Intussusception is invagination of one bowel segment into an adjacent bowel segment. It is rare in adults. Types - ileocolic, colocolic, enteroenteric, or jejunogastric.

Causes in adults are generally mechanical. Lead points involving colon are usually malignant (carcinoma, lymphoma) and of small bowel tend to be benign like lipoma, polyp, Meckel's diverticulum, sprue or lymphoid hyperplasia secondary to viral infection.

Gastrointestinal lipoma may be submucosal or subserosal. Intestinal intussusception by lipoma is uncommon. Rare when lipoma located in small intestine. Found in the ileum, duodenum and jejunum in decreasing order of frequency.

Adult intussusception is a rare disease and symptoms tend to be more chronic or intermittent with vague abdominal pain, nausea and vomiting, abdominal distension with partial obstruction, or palpable abdominal mass at physical examination.

CT - Target-like or sausage-like mass, the inner central area represents the invaginated intussusceptum surrounded by its mesenteric fat and associated vasculature, all of which are surrounded by the thick-walled intussuscipiens. If blood supply is compromised there is thickening of bowel loops.

Ultrasonography - Multilayered appearance consisting of the alternating hyperechoic and hypoechoic concentric rings that represent alternating layers of mucosa, bowel wall, and mesenteric fat in cross section.