Short segment, nonobstructing intussusceptions are commonly seen, rarely significant
• US: “Target,” “doughnut,” or bull’s-eye sign
TOP DIFFERENTIAL DIAGNOSES
• Primary bowel tumor
• Metastases and lymphoma
• Endometrial implant
• Meckel diverticulum
PATHOLOGY
• Tumor-related lead point
Benign: Polyp, leiomyoma, lipoma
Malignant: Primary (more common in colon), metastases and lymphoma (more common in SB)
• Physical cause, but no neoplasm
Postoperative causes are most common (e.g., adhesions, anastomoses)
• Intussusception in children
Usually attributed to lymphoid hyperplasia in distal SB
CLINICAL ISSUES
• Obstruction and ischemia are more common in long-segment intussusception with lead mass
(Left) Graphic shows an ileocolic intussusception with a tumor in the bowel wall as the lead mass. Note the vascular compromise and ischemia of the intussusceptum .
(Right) Coronal CECT shows invaginated mesenteric fat and vessels from an ileocolonic intussusception. The lead mass proved to be carcinoma.
(Left) Transverse color Doppler ultrasound of SB intussusception shows vascular flow within an intraluminal mass and 2 echogenic submucosal rings representing intussusceptum and intussuscipiens .
(Right) Transverse power Doppler ultrasound in the same patient reveals marked hyperemia within the mass, which proved to be a metastatic melanoma.
TERMINOLOGY
Definitions
• Invagination or telescoping of proximal segment of bowel (intussusceptum) into lumen of distal segment (intussuscipiens)
IMAGING
General Features
• Best diagnostic clue
Bowel-within-bowel, “coiled spring” appearance
• Location
Ileoileal > ileocolic > colocolic
Usually small bowel (SB) in adults, ileocolic in children
Colon: Malignant tumors more common than benign
SB: Benign tumors more common than malignant
Radiographic Findings
• Radiography
Air-fluid levels, proximal bowel dilatation, absence of gas in distal collapsed bowel
Fluoroscopic Findings
• Barium study
Classic “coiled spring” appearance
– Trapping of contrast between folds of intussusceptum and intussuscipiens
as the lead mass. Note the vascular compromise and ischemia of the intussusceptum 
.
and vessels 
from an ileocolonic intussusception. The lead mass proved to be carcinoma.
and 2 echogenic submucosal rings representing intussusceptum 
and intussuscipiens 
.
within the mass, which proved to be a metastatic melanoma.
