A patient develops generalized urticaria and mild bronchospasm within 5 minutes of intravenous iodinated contrast injection. According to ACR guidelines, this constitutes a:
- A Physiologic reaction — no treatment needed
- B Moderate acute contrast reaction — active treatment required ✓
- C Mild acute contrast reaction — observe and treat symptomatically
- D Severe anaphylactoid reaction — epinephrine mandatory
Explanation
ACR classifies acute contrast reactions as: Mild (self-limiting: scattered urticaria, nausea, single episode of emesis), Moderate (bronchospasm, diffuse urticaria, facial edema, vasovagal attack — require active treatment, may need epinephrine), and Severe (anaphylactic shock, convulsions, cardiorespiratory arrest — require epinephrine and resuscitation). Urticaria with bronchospasm constitutes a moderate reaction requiring active management including antihistamines and potentially epinephrine/beta-agonist nebulization. Physiologic reactions are anticipated responses like warmth, metallic taste, transient nausea.
Reference: Grainger & Allison's Diagnostic Radiology, 7th ed.
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