Meckel's diverticulum

Meckel diverticulum (also referred to as Meckel's Diverticulum) is the most common congenital abnormality of the small intestine an is caused by an incomplete obliteration of the vitelline duct , also known as the omphalomesenteric duct. It is named after Johann Friedrich Meckel, a German anatomist, who established its embryonic origin in 1809 (1). Meckel diverticulum is found in about 2% of the population , and occurs on the antimesenteric border of the ileum, usually 40-60 cm ( 2 feet) proximal to the ileocecal valve. The diverticulum is about 3 cm long and 2 cm wide. The diverticulum is typically lined by ileal mucosa. 50% of the diverticula are lined by heterotopic mucosa , most commonly the gastric mucosa. Peptic ulceration of this mucosa , as in the stomach, can lead to painless gastrointestinal bleeding, and/ or perforation. Other complications associated with Meckel diverticulum include intestinal obstruction , most commonly seen in adults (2). Meckel diverticulum can also get inflamed resulting in diverticulitis, although is less common than the other diverticula in the body because of the wide mouth and little lymphoid tissue. Nuclear scanning, called Meckel scan, is the preferred modality for the diagnosis of Meckel diverticulum in patients presenting with gastrointestinal bleeding. It is performed using a technetium-99m pertechnetate scintiscan (0.2mCi/kg in children and 10-20mCi in adults). After intravenous injection of the isotope, the gamma camera is used to scan the abdomen. This procedure usually lasts approximately 30 minutes. Ectopic gastric mucosa in the Meckel diverticulum secretes the radioactive isotope thus allows visualization as a hot spot. Meckel scan has a reported sensitivity of 80-90%, a specificity of 95% and an accuracy of 90%.Accuracy of the scan may be enhanced with administration of cimetidine, glucagon, and pentagastrin. Cimetidine enhances the uptake and blocks the secretion of technetium-99m pertechnetate from ectopic gastric mucosa, thus improving lesion to backfround ratio (3). Advantages of this procedure includes noninvasive nature, less radiation exposure, and more accurate than an upper GI and small-bowel follow-through study. False positive results can occur whenever ectopic gastric mucosa is present anywhere outside the Meckel diverticulum. False negative results can occur when gastric mucosa is very little in the diverticulum, in presence of necrosis of the diverticulum, or if superimposed on the bladder. Definitive treatment of a bleeding Meckel diverticulum is the surgical excision of the diverticulum along with the adjacent ileal segment, either laparoscopically or by laparotomy.