Ileal diverticulum

Ileal diverticulum (Meckel's diverticulum) is the most common congenital anomaly of the gastrointestinal tract and results from incomplete obliteration of the embryonic vitelline (omphalomesenteric) duct. It is a true diverticulum, containing all layers of the intestinal wall, and arises from the anti-mesenteric border of the ileum, typically about 60 cm (2 feet) proximal to the ileocaecal valve. Meckel's diverticulum usually measures approximately 5 cm (2 inches) in length and occurs in about 2% of the population, with symptomatic cases being more common in males.

Clinical correlates

The ileal diverticulum may contain ectopic gastric or pancreatic mucosa, with gastric mucosa being the most common. Acid secretion from ectopic gastric tissue can cause ulceration of the adjacent ileal mucosa, resulting in painless gastrointestinal bleeding, the most common presentation in children. Other complications include intestinal obstruction, intussusception, Meckel's diverticulitis, perforation, and peritonitis.

Although most individuals remain asymptomatic throughout life, Meckel's diverticulum is an important differential diagnosis in children with unexplained lower gastrointestinal bleeding and in patients presenting with symptoms that mimic acute appendicitis.

The rule of 2's for ileal diverticulum

The ileal diverticulum is commonly remembered by the rule of twos: it occurs in 2% of the population, is approximately 2 inches long, lies 2 feet from the ileocaecal valve, may contain two common types of ectopic mucosa (gastric and pancreatic), is twice as common in males, and often presents before the age of two years.