Meckel Diverticulum

Descriptive text is not available for this imageBASICS

DESCRIPTION

  • Meckel diverticulum (MD) is the most common congenital abnormality of the gastrointestinal (GI) tract.
  • Derives from remnants of the omphalomesenteric (vitelline) duct
  • Clinical presentation of MD in pediatric patients include the following:
    • Intestinal obstruction
    • Painless GI bleeding
    • Acute intraabdominal inflammation
    • Umbilical anomalies
  • Classically characterized by “Rule of 2’s”
    • Presents in approximately 2% of the population
    • Male-to-female ratio of 2:1 in symptomatic patients
    • Within 2 feet of the ileocecal valve
    • Can be up to 2 inches in length
    • Symptoms usually present by 2 years of age.

EPIDEMIOLOGY

  • MD as an anomaly occurs in ~2% of the population.
  • Majority of patients with MD will be asymptomatic.
  • Lifetime risk of developing a complication from a MD is 4%.
  • MD is considered to be more common in males, with a male-to-female ratio of 2:1.
  • Males also more likely to have symptomatic diverticula

PATHOPHYSIOLOGY

  • Normal development
    • Omphalomesenteric duct serves as a communication between the yolk sac and intestine in the fetus.
    • Obliteration of this duct normally occurs during the 5th week of gestation.
  • MD is a congenital anomaly resulting from the incomplete obliteration of the omphalomesenteric duct found in the distal ileum.
    • True diverticulum (contains all layers of the bowel wall) originating from the antimesenteric border of the bowel in the region of the terminal ileum proximal to the ileocecal valve
    • Diverticula with ectopic tissue are more likely to be symptomatic.
    • Ectopic tissue in MD is often of gastric origin; can also be composed of pancreatic, duodenal, or colonic tissue
  • 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 occurs 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 segmental volvulus.
  • MD accounts for 90% of the vitelline duct anomalies. Other anomalies include the following:
    • Omphalomesenteric fistula
    • Omphalomesenteric cyst
    • Fibrous band from diverticulum to abdominal wall

COMMONLY ASSOCIATED CONDITIONS

  • MD has also been associated with several other congenital anomalies that include the following:
    • Anorectal malformations (affects 11% of patients with MD)
    • Esophageal atresia (12%)
    • Minor omphalocele (25%)
    • Cardiac malformations
    • Exophthalmos
    • 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.

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