The differential diagnosis for this child's painless hematochezia includes Meckel's diverticulum as well as
vascular malformations. Meckel's diverticulum results from a failure of the vitelline duct to obliterate during the
first 8 weeks of gestation, leaving behind a blind pouch often containing ectopic gastric tissue. Meckel's
diverticulum classically affects children age ~:2 but can also occur in older children or even adults. Young
children are more likely to experience painless bleeding due to mucosal irritation from gastric acid;
adolescents and adults are more likely to have signs of obstruction.
A technetium-99 nuclear scan will identify the diverticulum, which is usually located in the right lower
quadrant of the abdomen within 2 feet of the ileocecal valve. Technetium-99 concentrates in the parietal cells
of the diverticulum and stomach. The scan is also known as "Meckel's scan" due to its high specificity. A
symptomatic Meckel's diverticulum is generally treated with surgical resection.