Meckel diverticulum

What it is

Meckel diverticulum arises from incomplete obliteration of the vitelline duct. Everything about it falls under the rule of two's: it occurs in 2% of the population, 2% of those are symptomatic and primarily in children under 2 years, it is twice as common in males as in females, it lies 2 feet proximal to the ileocecal valve, it is typically no more than 2 inches long, and it can carry 2 types of ectopic tissue, gastric and pancreatic.

How it presents

Many diverticula remain undetected. When it does speak, the most common presentation is lower gastrointestinal bleeding: the ectopic gastric mucosa or pancreatic tissue secretes acid and enzyme, which causes ileal ulceration and bleeding. What is seen is:

• Hematochezia, bright red blood in the stools
• Tarry stools, which indicate upper gastrointestinal bleeding
• Currant jelly stools, a mix of blood and mucus, as in intussusception
• Abdominal pain, typically in the right lower quadrant

How it is diagnosed

The Meckel scintigraphy scan is the test. It is noninvasive nuclear imaging with radiolabeled technetium, 99mTc, which identifies the ectopic gastric mucosa by preferential absorption. On the scan the stomach and the bladder light up as well as the diverticulum.