Penile Ultrasound: Doppler Protocol for PSV and EDV

Clinical Objective of the Study

Duplex ultrasound of the penis is used to document the anatomy of the corpora cavernosa, tunica albuginea, plaques, post-traumatic changes, and vascular response in erectile dysfunction. The practical standard is described in the AIUM Practice Parameter for the Performance of Penile Ultrasound, 2023. For the referring physician, not only the final PSV and EDV are crucial, but also the conditions under which they were obtained: pharmacostimulation, bilateral registration, angle correction, time after injection, and degree of erectile response.

Measurements outside a complete protocol may be falsely pathological: anxiety, pain, insufficient relaxation of the smooth muscle of the corpora cavernosa, and premature spectrum registration can reduce PSV or maintain diastolic flow without true veno-occlusive insufficiency.

Indications for the Vascular Protocol

• erectile dysfunction with the need to differentiate between arterial and veno-occlusive components;
• assessment of vascular response before reconstructive, endovascular, or andrological treatment;
• suspicion of vascular injury, arteriocavernous fistula, post-traumatic erectile dysfunction;
• priapism: differentiation of ischemic and non-ischemic variants in a clinical context;
• combination of erectile dysfunction with Peyronie's disease, fibrosis, deformation, or palpable mass.

Equipment and Patient Positioning

A high-frequency linear transducer is used; the frequency is chosen to be the maximum that provides sufficient depth and visualization of the cavernous arteries. The patient usually lies supine, with the penis placed on the anterior abdominal wall or a towel, without compressing the vessels with the transducer. In grayscale mode, the corpora cavernosa, spongiosum, tunica albuginea, septum, dorsal vessels, plaques, or fibrosis foci are documented.

Before injection, it is advisable to obtain baseline transverse and longitudinal images. This is important for comparing the diameter and course of the cavernous arteries, excluding significant calcinosis, hematoma, rupture of the tunica albuginea, or other causes affecting Doppler interpretation.

Pharmacostimulation and Safety

In the vascular protocol, AIUM allows intracavernosal administration of a vasoactive drug according to the local clinical policy of the institution. The study protocol records the drug, side, and time of administration, as well as the clinical degree of response. The physician performing the study should have an algorithm for monitoring and assisting with prolonged erection, pain, hematoma, or vasovagal reaction.

An important limitation: lack of sufficient erection after injection does not automatically equate to arterial insufficiency. The report should indicate that the pharmacological response was suboptimal if spectral criteria are evaluated under such conditions.

How to Perform Doppler Measurements

Cavernous arteries are assessed bilaterally, preferably in the proximal sections of the corpora cavernosa, where the vessel is usually better visualized and the insonation angle is controllable. Color or power Doppler is used to locate the artery, and then spectral Doppler is activated.

Angle correction is mandatory for quantitative velocity. According to AIUM parameters, the angle should not exceed 60°. The sample volume is placed within the artery lumen; gain, wall filter, and velocity scale are adjusted to avoid cutting off the systolic peak and masking low diastolic flow. For each side, the spectrum with PSV and EDV, time after injection, and angle correction is preserved.

PSV and EDV Timing Protocol

AIUM recommends serial registration after pharmacostimulation because the peak arterial response and venous outflow closure do not develop simultaneously. Practically, measurements are repeated at equal intervals, usually every 5 minutes, until the maximum response is reached or for 20–30 minutes. The conclusion includes the maximum PSV for each cavernous artery and the late EDV at adequate tumescence.

Interpretation of PSV

PSV reflects arterial inflow after relaxation of the cavernous smooth muscle. A value less than 25 cm/s after adequate pharmacostimulation is interpreted as a sign of arterial insufficiency. Bilateral reduction is more likely a systemic arterial component; unilateral reduction requires correlation with anatomy, trauma, local fibrosis, calcinosis, or technical measurement conditions.

The protocol should not be limited to a single number. It is necessary to indicate the maximum PSV on the right and left, the time of registration after injection, and the presence or absence of full erection. If the maximum PSV is reached late, this should also be described, as early values may be below the diagnostic level.

Interpretation of EDV

EDV assesses the maintenance of diastolic flow in the phase when venous outflow should be restricted by increased intracavernosal pressure. Persistent EDV greater than 5 cm/s after adequate arterial response corresponds to veno-occlusive dysfunction. The key condition is sufficient inflow: with low PSV, the conclusion about venous leakage based on EDV is unreliable.

Physiologically, the spectrum changes after injection: initially, systolic and diastolic flow increase, then as rigidity increases, the diastolic component decreases, may become zero or reverse. Therefore, early positive EDV alone is not a criterion for venous insufficiency.

What to Include in the Conclusion

• type of study: grayscale ultrasound, color, and spectral Doppler;
• presence of pharmacostimulation, drug according to local protocol, and time of administration;
• grayscale findings: plaques, calcifications, fibrosis, hematoma, defect of the tunica albuginea, deformation;
• PSV and EDV of the right and left cavernous artery with time after injection;
• Doppler angle correction if it affects reliability;
• quality of erectile response and study limitations;
• conclusion: no signs of arterial insufficiency / present; no signs of veno-occlusive dysfunction / present / assessment limited.

Typical Protocol Errors

• measurement of only one side in clinically significant asymmetry;
• lack of time after injection next to PSV and EDV;
• angle correction more than 60° or lack of angle correction;
• conclusion about venous leakage with low PSV or insufficient tumescence;
• premature termination of the study before 20–30 minutes with ongoing velocity increase;
• excessive compression by the transducer, altering the spectrum of superficially located vessels.

Short Template for Formulation

“After intracavernosal pharmacostimulation, serial spectral Doppler of both cavernous arteries was performed with an angle correction of no more than 60°. Maximum PSV on the right — ... cm/s at ... minute, on the left — ... cm/s at ... minute. EDV on the right — ... cm/s, on the left — ... cm/s in the late phase of the study. Erectile response ... . Data for arterial insufficiency / veno-occlusive dysfunction ... . Limitations: ...”