Meckel diverticulum

Epidemiology

• Prevalence: most common congenital gastrointestinal tract anomaly
• Rule of 2s for Meckel’s Diverticulum
  • 2% of the population
  • 2 feet from the ileocecal valve
  • 2 inches in length
  • 2 years is the most common age for symptomatic presentation
  • 2 types of heterotopic mucosa (gastric and pancreatic)

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Etiology

• True congenital diverticulum resulting from incomplete obliteration of the vitelline (omphalomesenteric) duct.
• Contains all three layers of the small intestine wall.
• Often contains ectopic tissue, most commonly gastric mucosa (>60%), which can secrete acid and cause ulceration and bleeding. Pancreatic tissue is the second most common.
  • The vitelline duct is lined with pluripotent cells, meaning they have the ability to differentiate into various types of specialized cells.

Tip

Similar to Urachal abnormalities

Feature	Vitelline Duct	Allantois (Urachus)
Connects	Midgut to Yolk Sac	Bladder to Umbilicus
Adult Remnant	None (normally)	Median Umbilical Ligament
Pathology	Meckel Diverticulum	Patent Urachus
Classic Sx	Painless rectal bleeding (child)	Urine discharge from umbilicus
Cancer Risk	N/A	Adenocarcinoma of bladder (dome)

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Pathophysiology

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Clinical features

• Most are asymptomatic and found incidentally.
• If symptomatic, classic presentation is painless rectal bleeding (maroon or “currant jelly” stools) in a child &lt 2 years old.
• Can also present with symptoms of complications like intestinal obstruction or diverticulitis (mimicking appendicitis).
• In adults, intestinal obstruction is the most common presentation, while bleeding is less frequent.

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Diagnostics

Meckel scintigraphy scan (Meckel scan): a noninvasive nuclear medicine imaging technique using radiolabelled technetium (^99mTc), which is preferentially absorbed by the gastric mucosa and can identify ectopic gastric mucosa

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Treatment

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Complications

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• Bowel obstruction (usually affects terminal ileum) due to
  • Intussusception
  • Volvulus