In painless rectal bleeding in a child, a focus of pertechnetate uptake in the right lower quadrant appearing with the gastric uptake and persisting is ectopic gastric mucosa in a Meckel diverticulum; in obstruction or diverticulitis, CT shows a blind-ending pouch off the ileum.
Orient first
- Rule of twos: 2% of people, 2 feet from the ileocaecal valve, about 2 inches long, symptomatic under 2 years.
- Bleeding is from ulceration of adjacent ileum by acid from ectopic gastric mucosa.
- Complications: bleeding, intussusception, volvulus around a band, diverticulitis.
Acquire the study
- Tc-99m pertechnetate; dynamic images then static anterior and lateral images to 30–60 min; post-void images.
The manoeuvre
- Focal uptake in the right lower quadrant appearing at the same time as the gastric uptake.
- Intensity increasing with time and fixed in position on lateral and post-void images.
- Exclude renal pelvis, ureter and bladder activity and a duplication cyst.
What confirms it
- Focal pertechnetate uptake with the timing and persistence of gastric mucosa; or a blind pouch at surgery.
What licenses you to exclude it
- A negative Meckel scan lowers the likelihood; diverticula without gastric mucosa are not shown by it.
The classic misread
- Calling urinary activity a Meckel — lateral and post-void images settle it.
- Calling a Meckel diverticulitis appendicitis on CT when the appendix was not identified separately.