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Meckels diverticulum short note 5 mark in easy words

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Meckel diverticulum

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Meckel's Diverticulum (Short Note)

Definition Meckel's diverticulum is a true congenital diverticulum of the small intestine - a small pouch sticking out from the ileum. It's called "true" because it contains all 3 layers of the bowel wall (mucosa, muscularis, serosa), unlike acquired diverticula (like in the colon) which lack a proper muscle layer.
Cause It happens due to failure of the vitelline duct (omphalomesenteric duct) to close during fetal development. This duct normally connects the gut to the yolk sac and disappears before birth - if a part of it persists, you get this diverticulum.
"Rule of 2's" (easy way to remember)
  • Occurs in about 2% of the population (most common GI congenital anomaly)
  • Found within 2 feet (60 cm) of the ileocecal valve
  • About 2 inches (5 cm) long
  • Male:Female ratio = 2:1
  • Usually becomes symptomatic by age 2 years (though only ~4% ever cause symptoms)
  • Located on the antimesenteric border of the ileum (opposite side to where the mesentery attaches)
Pathology The lining may look like normal small intestine, but often contains ectopic (misplaced) tissue - most commonly gastric mucosa, sometimes pancreatic tissue. The gastric mucosa secretes acid, which can ulcerate the nearby normal ileal mucosa.
Clinical Features
  • Often asymptomatic, found incidentally
  • When symptomatic, presents with:
    • Painless rectal bleeding (due to peptic ulceration from ectopic gastric tissue) - most common presentation in children
    • Intestinal obstruction (due to intussusception, volvulus, or a fibrous band)
    • Diverticulitis - can mimic acute appendicitis in symptoms
Diagnosis
  • Meckel's (technetium-99m pertechnetate) scan - taken up by ectopic gastric mucosa, gold standard in children
  • CT/ultrasound in some cases
Treatment
  • Surgical resection (diverticulectomy or segmental bowel resection) if symptomatic
  • Asymptomatic ones found incidentally are usually left alone unless certain risk features are present (e.g., narrow neck, palpable ectopic tissue)
  • Robbins, Cotran & Kumar Pathologic Basis of Disease, p. 1490
Quick summary line for exam: Meckel's diverticulum is a true congenital ileal diverticulum from a persistent vitelline duct, following the "Rule of 2's," often containing ectopic gastric/pancreatic tissue, presenting with painless GI bleed, obstruction, or diverticulitis mimicking appendicitis, diagnosed by Meckel's scan, and treated by surgical resection.
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