Following papaverine injection to induce erection, measurements are obtained for up to how long post-injection?

• A. Immediately after
• B. 1-2 mins post injection
• C. 10-12 mins post-injection
• D. Up to 6 mins post-injection

Answer: (D)

Pharmacologic penile duplex ultrasound uses intracavernosal papaverine to induce an erection and then captures arterial inflow and venous leakage during a short, standardized window. The goal is to measure while the penis is fully engorged and the cavernosal arteries are actively dilated, which happens in the early minutes after injection. This keeps the hemodynamic readings—such as peak systolic velocity and end-diastolic velocity—reliable and comparable. If you wait much longer, the erection begins to subside and the drug effect wanes, altering velocities and making interpretation less dependable. That’s why measurements are taken up to about six minutes after injection.