FREQUENCY: 2% of the population
PATIENT HISTORY: This was an incidental finding in a 20 year old woman who died of an unrelated cause.
Proximal to the ileo-caecal valve by 75cm was this unusually large Meckel diverticulum. On histology there was no evidence of any heterotopia, as is commonly seen.
This common congenital anomaly is usually a 1-5cm finger-like projection on the anti-mesenteric surface of the mid-ileum. It is a blind outpouching of the ileum that includes all three layers of the intestinal wall, viz. mucosa, submucosa and muscularis propria. However, ectopic gastric or pancreatic tissue is quite often present (known as heterotopia). Gastric mucosa which secretes acid can cause ulceration of the adjacent intestinal mucosa, causing pain (resembling appendicitis), bleeding per rectum or even intestinal perforation. Another occasional complication of Meckel diverticulum occurs when the diverticulum inverts into the intestinal lumen and becomes the lead point of an intussusception.
The "rule of 2's" is can be used to remember characteristics of Meckel diverticulae:
They occur in approximately 2% of the population.
They are generally found within 2 feet (60cm) of the ileocaecal junction.
They are approximately 2 inches (5cm) long.
They are twice as common in males as in females
Though a very small percentage are symptomatic, those that are, are symptomatic by the age of two years.
A Meckel diverticulum occurs when the omphalomesenteric duct (vitelline duct), which connects the yolk sac to the lumen of the developing gut, is incompletely obliterated. See diagram.
PREVENTION & TREATMENT:
If symptomatic, a Meckel diverticulum is surgically excised.