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- Meckel diverticulum (MD) is the most common congenital abnormality of the GI tract.
- Derives from the omphalomesenteric duct remnants
- The most common clinical presentation in children of MD is painless rectal bleeding.
- Classically characterized by “Rule of 2’s”
- Present in approximately 2% of the population
- Male-to-female ratio 2:1
- Within 2 feet of the ileocecal valve
- Can be up to 2 inches in length
- Symptoms usually present by 2 years of age.
- MD as an anomaly occurs in ~2% of the population, but only ~4% of patients with MD develop symptoms over their lifetime.
- MD is more common in patients with other malformations including anorectal atresia, esophageal atresia, omphalocele, and cardiac abnormalities.
- MD is considered to be more common in males, with a male/female ratio of 2:1.
- Males are also more likely to have symptomatic diverticula.
- Diverticula with ectopic tissue are more likely to be symptomatic.
- Ectopic tissue in MD is often of gastric origin; can also be comprised pancreatic, duodenal, or colonic tissue as well
- Bleeding occurs when gastric mucosa is present, resulting in peptic ulcerations of the small bowel downstream from the diverticulum (90% of cases).
- Alkaline secretions from ectopic pancreatic tissue can also cause ulcerations with bleeding.
- Obstruction can occur when the diverticulum acts as a lead point for intussusception, when the diverticulum becomes inflamed with subsequent lumen narrowing, or when the diverticulum induces a volvulus.
- True diverticulum (contains all 3 layers of the bowel wall)
- Originates from the antimesenteric border of the bowel in the region of the terminal ileum and proximal to the ileocecal valve
- Remnant of the omphalomesenteric (vitelline) duct which fails to involute completely during the 5th–6th week of gestation as the placenta replaces the yolk sac as the source of fetal nutrition
- MD accounts for 90% of the vitelline duct anomalies. Other anomalies include the following:
- Omphalomesenteric fistula
- Omphalomesenteric cyst
- Fibrous band
Commonly Associated Conditions
- MD has also been associated with several other congenital anomalies that include the following:
- Anorectal atresia (affects 11% of patients with MD)
- Esophageal atresia (12%)
- Minor omphalocele (25%)
- Cardiac malformations
- Cleft palate
- Annular pancreas
- Some central nervous system malformations
- Malignancies have also been reported in association with MD.
- Can be present within the diverticulum and can cause obstructive symptoms or can be found incidentally
- Sarcomas are the most common malignancy associated with MD, followed by carcinoids and adenocarcinomas.