Which techniques are performed in penile pressure and waveform testing?

• A. Duplex scan before and after injection with papaverine or prostaglandin; CW Doppler, 8-10 MHz; Plethysmography
• B. MRI penile vessels
• C. CT angiography of pelvic arteries
• D. Venography of penis

Answer: (A)

Penile pressure and waveform testing is about assessing the vascular hemodynamics of an erection, not just anatomy. The best approach combines a duplex ultrasound with pharmacologic erection provocation and a measure of penile volume change. A duplex scan is performed to visualize the cavernosal arteries and monitor blood flow, and it is done both before and after injecting a vasodilator such as papaverine or prostaglandin E1 to induce an erection in a controlled way. Using continuous-wave Doppler and a high-frequency transducer (8–10 MHz) allows accurate measurement of flow velocities and waveforms in the penile arteries, helping us assess arterial inflow and resistance. Watching how the waveform and velocities change after pharmacologic stimulation reveals whether arterial inflow is adequate or impaired and whether venous leakage might be present. Plethysmography then quantifies changes in penile volume or blood content during the erection, providing an additional functional measure of the vascular response.

MRI penile vessels, CT angiography, and venography are structural or venous-imaging studies that focus on anatomy rather than the dynamic pressure and flow data obtained with this testing approach, so they don’t replace the combination described here.