Meckel's diverticulum

A Meckel's diverticulum is a true congenital diverticulum. It is a vestigial remnant of the omphalomesenteric duct and is the most frequent malformation of the gastrointestinal tract. It is present in about 2% of the population, with an equal distribution between males and females, but causing trouble more commonly in males than females. It is named after Johann Friedrich Meckel, who first described this type of diverticulum in 1809.

Most people with a Meckel's are asymptomatic but of those who do develop symptoms, most will do so in childhood.

Meckel's diverticulum is located in the distal ileum, usually within about 60-100cm of the ileocecal valve. It is usually about 3-5cm long, runs antimesenterically and has its own blood supply. Thus, a useful memory aid is "2 percent - 2 feet - 2 inches".

The most common presentation is of painless rectal bleeding, followed by intestinal obstruction, volvulus and intussusception. Occasionally, Meckel's diverticulitis may present with all the features of acute appendicitis.

A technetium-99m (99mTc) pertechnetate scan is the investigation of choice to look for a Meckel's. This scan detects gastric mucosa - as a Meckel's diverticulum often has ectopic gastric (stomach) cells contained within it, this shows up as a spot on the scan distant from the stomach proper. Other tests such as colonoscopy should be performed as well as screening for bleeding disorders.