The axial images of the contrast-enhanced CT scan of the abdomen and pelvis, as well as the associated sagittal reformation, demonstrated a transverse colonic intussusception. Figures 1-4 show the proximal contrast-filled intussusceptum invaginating into the distal intussuscipiens (which is relatively hypodense in appearance, because it does not contain oral contrast) in the left upper quadrant. Mesenteric fat and vessels are noted between the intussusceptum and intussuscipiens, which creates a "target" or "bowel-within-bowel" appearance. This is a characteristic CT appearance of an intussusception.
An adult presenting with intussusception is uncommon. Children constitute most patients affected by intussusception, with adults representing only 5% of cases. Adult intussusception accounts for 1% of bowel obstructions and only 0.002% of all hospital admissions. In 70%-90% of cases of adult intussusception, an underlying organic cause is found. This is in contrast to the pediatric population, which has an idiopathic form in over 95% of cases.[1,2]
Intussusception occurs between adjacent segments of bowel. The intussusceptum, a prolapsing segment of bowel, invaginates with its mesentery into a recipient segment of bowel, known as the intussuscipiens, like a telescope. This may be transient, but if it is persistent, it can cause bowel obstruction; if left untreated, it can result in bowel ischemia, eventual sepsis, and death.
Intussusception is commonly classified according to location: enteroenteric, ileocolic, ileocecal, or colocolic. Most cases in adults involve the small bowel or a combination of the small and large bowels. In adults, colocolic intussusception occurs in less than 20% of cases.[3,4]
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