Meckel diverticulum, and true vs false diverticula
- Lesion
A small pouch left over from the yolk-sac duct sits on the ileum; it can bleed, block the bowel or mimic appendicitis.
What it is
Meckel diverticulum is the commonest congenital anomaly of the gut and the classic true diverticulum: a blind pouch that keeps all layers of the bowel wall. It forms when the vitelline (omphalomesenteric) duct, which links the embryonic gut to the yolk sac, fails to involute. Most cause no trouble; when they do, it is usually because ectopic gastric mucosa in the pouch secretes acid and ulcerates the ileum beside it.
Structure
- A solitary finger-like pouch on the antimesenteric side of the distal ileum.
- Wall: mucosa, submucosa and muscularis propria, like the normal bowel.
- Lining: small-bowel mucosa, sometimes with islands of gastric (acid-secreting) or pancreatic tissue.
- Peptic ulcer in the adjacent ileal mucosa when gastric tissue is present.
True vs false diverticula
| Feature | True diverticulum | False (pseudo-) diverticulum |
|---|---|---|
| Wall | All layers, including muscularis propria | Mucosa and submucosa only, through a gap in the muscle |
| Origin | Usually congenital | Acquired, from raised pressure |
| Examples | Meckel diverticulum; the appendix itself | Sigmoid diverticula, Zenker, epiphrenic diverticula |
Clinical notes
- Painless bright or dark rectal bleeding in a young child: think of ectopic gastric mucosa.
- Inflammation (Meckel diverticulitis) mimics acute appendicitis.
- The pouch can act as the lead point of an intussusception or twist the bowel (volvulus).
In the lab
- A technetium-pertechnetate scan picks up the ectopic gastric mucosa.
Test yourself
Think of the answer, then tap the question to see it.
Why is Meckel diverticulum called a true diverticulum?
Its wall contains all the layers of the bowel, including the muscularis propria.
Which embryonic structure fails to involute in Meckel diverticulum?
The vitelline (omphalomesenteric) duct that joined the midgut to the yolk sac.
What causes bleeding from a Meckel diverticulum?
Acid from ectopic gastric mucosa in the pouch ulcerates the adjacent ileal mucosa.
Elsewhere in DurgiPedia
Connections
Educational content on the mechanisms of disease; not a diagnostic or treatment guide and no substitute for a health professional's advice. No doses are given.
Sources: Meckel diverticulum: MedlinePlus Medical Encyclopedia (MedlinePlus, US National Library of Medicine, 2025).
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Representative model, for educational purposes only.