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IMAGE INTERPRETATION · HEPATOBILIARY AND GI

Active Lower GI Bleed on Tagged RBC Scan

Tc-99m RBC scan (ANT 60 min, sequential frames) — focal activity appearing in the right lower quadrant and migrating along the colon, indicating active GI hemorrhage
Tc-99m RBC scan (ANT 60 min, sequential frames) — focal activity appearing in the right lower quadrant and migrating along the colon, indicating active GI hemorrhage

Provided clinical image

Question

A Tc-99m red blood cell (RBC) scan is performed in a patient with hematochezia and a hemoglobin drop. The scan shows a focal area of activity in the right lower quadrant that INCREASES and MOVES (migrates) on sequential images. This pattern is MOST consistent with:

  1. AHepatic hemangioma — stable RBC uptake in the liver
  2. BArtifact from patient motion
  3. CActive lower GI bleeding in the right colon — activity appears, increases, and moves along the bowel lumen as bleeding progresses
  4. DMeckel's diverticulum
Show the answer and explanation

C. Active lower GI bleeding in the right colon — activity appears, increases, and moves along the bowel lumen as bleeding progresses

Tc-99m RBC scanning is used to localize active GI bleeding. The key feature of a true bleed is: (1) NEW focal activity appearing where none was before (vs. physiologic activity in heart, great vessels, liver, spleen, kidneys, bladder); (2) INCREASING activity over time; (3) MIGRATION along the bowel lumen in the direction of peristalsis. This dynamic pattern distinguishes true hemorrhage from hepatic hemangioma (stable, non-migratory) or background activity. Tc-99m RBC scan can detect bleeding rates as low as 0.04–0.1 mL/min, making it more sensitive than angiography (0.5–1 mL/min) for intermittent bleeds. Positive scans guide selective angiography and hemostasis.

More hepatobiliary and gi images

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← Biliary Atresia on Neonatal HIDA ScanNormal Hepatobiliary Scan Sequence (Mebrofenin) →

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