Active GI bleed? (CTA)

Hematochezia or melena with falling hemoglobin; IR is asking whether there is a target to embolize.

Answer the surgeon

IR embolization vs endoscopy vs observation — IR needs the vessel and the bowel segment.

Your answer must state:

Active extravasation: yes or no
Location by segment/quadrant
Likely culprit artery or territory
Sentinel clot marking a recent source even without active bleeding

Key and direct findings

1.Active extravasation
A focal intraluminal contrast blush on the arterial phase, absent on unenhanced, that changes shape or spreads on the delayed phase.
2.Use all three phases
Unenhanced = baseline for pre-existing density; arterial = extravasation appears; delayed = pooling spreads (active) or stays identical (not blood).
Pitfall: Ingested material, sutures, and clips mimic extravasation — the unenhanced pass exists to unmask them.

Supportive signs & checks

1.Sentinel clot
Hyperdense (>60 HU) intraluminal clot marks the recent bleeding site even when active extravasation has stopped.
2.Rate sensitivity
Experimental detection thresholds for CTA are often quoted at roughly 0.3–0.5 mL/min, but real-world sensitivity depends on active bleeding during acquisition and protocol quality.
3.No positive oral contrast
Positive oral contrast hides the blush entirely; if it was given, say the study cannot exclude active bleeding.
4.Bleeding is intermittent
A negative CTA does not exclude a source — state it so the team keeps the patient monitored.
Pitfall: Do not let a clean CTA read as 'no GI bleed' — it means 'not bleeding during the scan'.

Wet-read snippets

Fill the blanks, then copy into your preliminary report.

Positive

Active extravasation in the ___ (arterial-phase focus enlarging on delayed phase), territory of the ___ artery — suitable target for angiographic embolization.

Negative

No active extravasation on arterial or delayed phases; ___ sentinel clot. Negative CTA does not exclude intermittent bleeding.

Sources

CT for evaluation of acute gastrointestinal bleeding — Wells ML et al. RadioGraphics (2018)
Management of patients with acute lower GI bleeding: updated ACG guideline — Sengupta N et al. Am J Gastroenterol (2023)

Content review: Content pending clinical review · 2026-07-15

Educational reference for trained clinicians. Verify every result against the cited original guideline before use. Not a substitute for clinical judgment or medical advice.