Before administering intravenous alteplase in suspected acute ischemic stroke, which test is essential to rule out hemorrhage?

• A. MRI of the brain with gadolinium.
• B. Noncontrast CT head.
• C. CT angiography.
• D. Lumbar puncture.

Answer: (B)

The key idea is that giving IV alteplase requires ruling out intracranial hemorrhage quickly, because tPA can worsen bleeding. The fastest and most reliable way to do this in the acute setting is a noncontrast CT scan of the head. It is widely available in emergency departments, takes only minutes, and can detect acute intracranial hemorrhage without any contrast, allowing safe decision-making about thrombolysis within the therapeutic window.

MRI with gadolinium can detect hemorrhage and other pathology, but it takes longer and is not as practical for immediate hemorrhage exclusion before thrombolysis. CT angiography adds information about blood vessels and occlusions but is not the primary test to rule out hemorrhage and it delays treatment. Lumbar puncture is invasive and unnecessary for ruling out hemorrhage when a noncontrast CT has already been performed, and it would delay therapy.