Mesenteric ischemia? (CTA)

CTWSES 2022

Pain out of proportion to examination, often with AF or a low-flow state; every hour of delay costs bowel.

Answer the surgeon

Emergent revascularization plus resection of non-viable bowel vs anticoagulation (venous) vs treating the low-flow state (NOMI).

Your answer must state:

Mechanism: SMA embolus (abrupt mid-SMA cutoff, no collaterals, AF) vs in-situ thrombosis (ostial, calcified plaque, collaterals) vs SMV thrombosis vs NOMI (diffuse narrowing, vasopressors)
Bowel viability: wall enhancement present or absent
Advanced bowel-injury signs: interpret pneumatosis and portomesenteric venous gas in context; identify frank perforation

Key and direct findings

1.SMA or SMV filling defect / occlusion
Embolus lodges a few cm from the SMA origin at a branch point; in-situ thrombosis sits at the calcified ostium with collaterals; SMV thrombosis is a venous filling defect with congested mesentery.
Pitfall: You need a true arterial phase — a portal-venous-only study can hide the arterial cutoff.
2.Absent or reduced bowel-wall enhancement
The most specific sign of infarcting bowel — compare segment against segment.
3.Pneumatosis with portomesenteric venous gas
In the clinical context of acute mesenteric ischemia, the combination strongly suggests advanced, potentially irreversible bowel injury; frank perforation confirms transmural injury.

Supportive signs & checks

1.Venous pattern: thick edematous wall
SMV thrombosis produces wall thickening, mesenteric fat haziness, and ascites — a congested, not necessarily dead, bowel.
Pitfall: Arterial ischemia classically shows a thin, dilated wall — wall thickening is the venous/reperfusion pattern, not the arterial one.
2.Check the unenhanced series
Hyperdense intramural hemorrhage marks ischemic wall injury before contrast confuses the picture.
3.NOMI pattern
Diffuse, irregular SMA narrowing with patent trunk in a shocked or vasopressor-dependent patient.
Pitfall: Early ischemia can look near-normal — with high clinical suspicion, a negative CT warrants repeat imaging or angiography, not reassurance.

Wet-read snippets

Fill the blanks, then copy into your preliminary report.

Positive

Acute mesenteric ischemia: ___ (SMA embolic occlusion ___ cm from origin / ostial SMA thrombosis / SMV thrombosis) with ___ bowel-wall enhancement of ___. Pneumatosis/portal venous gas: ___.

Negative

Patent SMA, SMV and celiac axis with normal bowel-wall enhancement — no CTA evidence of mesenteric ischemia.

Sources

WSES guidelines for acute mesenteric ischemia (2022 update) — Bala M et al. World J Emerg Surg (2022)
Diagnostic accuracy of multidetector CTA in acute mesenteric ischemia — Menke J. Radiology (2010)

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.