A 4-year-old boy has recurrent painless lower gastrointestinal bleeding. A technetium-99m pertechnetate scintigraphy is performed and shows a focal area of tracer accumulation in the right lower quadrant appearing simultaneously with gastric mucosa. This test detects the bleeding source because pertechnetate is taken up by:

• A Colonic epithelial cells via the sodium iodide symporter
• B The aberrant pancreatic tissue lining the diverticulum
• C Arterially shunted blood within the vitellointestinal remnant
• D Ectopic gastric mucosa within the diverticulum ✓

Explanation

Meckel's scan exploits the fact that gastric mucosal cells actively take up and secrete pertechnetate. Most bleeding Meckel's diverticula contain ectopic gastric mucosa, so focal tracer activity in the right lower quadrant that appears synchronously with the stomach confirms the diagnosis. Sensitivity is highest in children. The NIS symporter mediates iodide uptake in thyroid and salivary tissue, not pertechnetate uptake in colon, and pancreatic rest does not concentrate the tracer.

Reference: Nelson Textbook of Pediatrics, 21st ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.