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Meckel diverticulum is the most common congenital anomaly of the gastrointestinal tract, occurring in approximately 2% of the population as a remnant of the omphalomesenteric duct. It is a true diverticulum containing all layers of the bowel wall, typically located within 2 feet of the ileocecal valve and measuring about 2 inches in length.
The diverticulum results from incomplete obliteration of the omphalomesenteric duct during fetal development, leaving a blind-ending pouch that projects from the antimesenteric border of the ileum. Complications arise when the diverticulum contains ectopic gastric mucosa (found in 50% of cases), which can secrete acid and cause peptic ulceration of adjacent normal ileal mucosa.
Most Meckel diverticula remain asymptomatic throughout life, but complications can include gastrointestinal bleeding (most common in children), intestinal obstruction from intussusception or volvulus, and diverticulitis mimicking appendicitis. The classic presentation involves painless rectal bleeding in a young child, and diagnosis can be confirmed with a technetium-99m pertechnetate scan that detects ectopic gastric mucosa.