Meckel's Diverticulum Embryology and Sequelae

The correct answer is D.

Explanation:

A Meckel's diverticulum is caused by failure of obliteration of the vitello-intestinal duct. It is classically located in the distal ileum within 30 cm of the ileocecal valve, and the structure is a true diverticulum with mucosa, submucosa, and muscularis propria. Many Meckel's diverticula contain ectopic pancreatic tissue or gastric mucosa, and the acid production from the gastric mucosa may be sufficient to produce a small peptic ulcer in adjacent intestinal mucosa. Such small peptic ulcers are occasional sources of mysterious appendicitis-like pain or intestinal bleeding. Peptic ulceration adjacent to a Meckel's diverticulum should be suspected in any child who presents with massive, painless rectal bleeding. Technetium [99mTc] concentrates in gastric mucosa, and the scan in this patient demonstrated a small amount of ectopic gastric mucosa located in the diverticulum.

Acute appendicitis (choice A) is usually very painful and does not typically cause rectal bleeding.

A lesion of the cecum (choice B) would have been revealed by thorough colonoscopy.

Failure of upper endoscopy to demonstrate a peptic ulcer of the duodenum (choice C) makes duodenal disease unlikely.

Theoretically, the jejunum (choice E) could have been the source of the problems, but jejunal bleeding is uncommon and a Meckel's diverticulum is a much more likely possibility.

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