What is the approved intravenous thrombolysis window for eligible ischemic stroke patients?

• A. Within 3 hours of symptom onset
• B. Within 4.5 hours of symptom onset
• C. Within 6 hours of symptom onset
• D. Within 24 hours of symptom onset

Answer: (B)

Timing is what this question is testing: when IV thrombolysis can be safely given to dissolve a clot in ischemic stroke. The approved window for giving IV alteplase to eligible patients is within 4.5 hours from when symptoms began. This extended window, chosen after research, still requires careful screening for contraindications (like bleeding risks, very high blood pressure, or certain blood test abnormalities), but it allows treatment up to 4.5 hours to improve chances of recovery. Treatments beyond this window aren’t routinely recommended because the risk of hemorrhage outweighs the benefits, and shorter times (earlier treatment) generally yield better outcomes. So the best choice reflects the 4.5-hour limit.