Which is a key eligibility criterion for IV thrombolysis in acute ischemic stroke?

• A. Onset within 24 hours, any BP, presence of intracranial hemorrhage allowed
• B. Onset within 4.5 hours, no intracranial bleed on CT, baseline BP controlled below 185/110, no recent major surgery or active bleeding risk
• C. Onset within 6 hours, severe anemia
• D. Onset within 2 hours, history of hemorrhagic stroke in the past year

Answer: (B)

IV thrombolysis for acute ischemic stroke is given only to patients who are likely to benefit from clot dissolution without an unacceptable risk of bleeding. The most important eligibility criteria include a symptom onset within a limited time window, imaging that excludes hemorrhage, and physiological factors that minimize bleeding risk. Specifically, treatment is considered when symptoms began within 4.5 hours, a brain CT shows no intracranial bleed, baseline blood pressure can be controlled to below 185/110, and there is no recent major surgery or active bleeding risk. These conditions together reduce the chance of converting a ischemic stroke into a hemorrhagic one while allowing the drug to help restore blood flow.

This is why the correct choice is the best: it accurately reflects the critical time frame, the need to rule out intracranial hemorrhage on imaging, and the key safety thresholds for blood pressure and recent procedures or bleeding risks. The other options misstate the time window or include contraindications that would make thrombolysis unsafe, such as a history of hemorrhagic stroke or allowing a hemorrhage on imaging.