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Lead screening risk — USMLE Step 3 MCQ

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HardPediatrics (well-child, chronic management)Lead screening riskUSMLE Step 3

A 79-year-old with atrial fibrillation not taking anticoagulation develops abrupt severe periumbilical pain with minimal tenderness. Lactate is 3.4 mmol/L, creatinine is 2.1 mg/dL from a baseline of 1.3, and there is no peritonitis or shock. What is the best diagnostic test now?

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Correct answer: C — Obtain contrast-enhanced CT angiography of the abdomen and pelvis now despite the kidney injury

The best answer is “Obtain contrast-enhanced CT angiography of the abdomen and pelvis now despite the kidney injury”. The presentation is high risk for acute embolic mesenteric ischemia. ACR rates contrast-enhanced CT angiography as the usually appropriate initial examination; noncontrast CT, ultrasound, and delayed lactate-based strategies can miss early vascular occlusion. The mortality from diagnostic delay outweighs the manageable kidney risk of iodinated contrast in this time-critical setting.

Reference: ACR Appropriateness Criteria: Imaging of Mesenteric Ischemia: https://acsearch.acr.org/docs/70909/narrative/