GI Radiology > Small Bowel > Structural Abnormalities

Structural Abnormalities

Meckel’s Diverticulum

Meckel’s diverticulum is the failed obliteration of intestinal end of omphalomesenteric duct.  It is a true diverticulum, containg all three muscular layers of the bowel wall. It occurs in the distal ileum, usually within 100cm of the ileocecal valve. It is common, present 2-3% of autopsies. The majority of Meckel’s diverticula are asymptomatic, and 50% contain heterotopic mucosa (usually gastric, or less commonly pancreatic). Those that do present clinically have variable presentations. The most common presentation in adults is GI bleeding, a result of ectopic gastric mucosa. Children more often present with small bowel obstruction, as the diverticulum acts as a lead point for intussusception. Rarer complications include diverticulitis (“pseudoappendicitis”) or perforation.

Radiological

Plain films are often normal, but demonstrate distal SBO or enteroliths. Generally, plain films do not play a major role in the diagnosis of Meckel’s.

Fluoroscopy demonstrates the diverticulum as a contrast-filled outpouching from the distal ileum. Rugae may be seen as a result of ectopic gastric mucosa, and and complications, such as intussusception or ulceration, may be identified.

Nuclear medicine can aid in the diagnosis of Meckel’sdiverticulum, but only if it contains gastric mucosa. A “Meckel’s scan” (technetium-99m-pertechnetate) selectively localizes to gastric mucosa, with a positive study showing abnormal activity in the lower abdomen. This test is particularly effective at identifying Meckel’s diverticula as the cause of GI bleeding, because a bleeding Meckel’s diverticulum invariably contains ectopic gastric mucosa.

         

Meckel’s diverticulum.  Enteroclysis demonstrates a saccular outpouching. Meckel's scan (Tc-99m-labeled RBCs) shows abnormal uptake in the lower abdomen. Increased uptake is seen in diverticula that contain ectopic gastric mucosa.

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