Can Cavernous Artery Doppler Ultrasound Be Done Without Inducing Erection?
No, in this clinical scenario of suspected non-ischemic priapism, the penile duplex Doppler ultrasound (PDUS) should be performed in the erect state to properly identify the cavernous artery fistula location and assess blood flow characteristics.
Guideline-Based Rationale
The 2022 AUA/SMSNA priapism guidelines explicitly state that "ultrasonography should be performed in the erect state and both penile shaft and perineum should be scanned" when evaluating non-ischemic priapism 1. This is not optional—it's the standard approach for proper diagnostic evaluation.
Why the Erect State Is Essential
In non-ischemic (high-flow) priapism, which your patient's presentation suggests (persistent semi-erections, non-painful, following likely trauma), the key diagnostic findings include:
- Turbulent flow detection at the cavernous artery fistula site
- Normal to high velocities in the cavernous arteries (distinguishing from ischemic priapism)
- Identification of pseudoaneurysm location and size
- Mapping for potential embolization planning
These critical findings are only reliably visualized when adequate blood flow is present through the arterial system during erection 1.
Technical Considerations
The examination should be performed with the patient in lithotomy or frog-leg position, scanning the perineum first, then along the entire penile shaft 1. This positioning and technique is specifically designed for the erect state evaluation.
If Natural Erection Is Insufficient
While your patient has persistent semi-erections, if these are not adequate for proper visualization, pharmacologic induction with intracavernosal alprostadil may be necessary 2, 3. The goal is achieving complete cavernosal smooth muscle relaxation and adequate rigidity for accurate hemodynamic assessment.
Clinical Pitfall to Avoid
Attempting PDUS in a flaccid or inadequately erect state will likely miss the fistula, fail to demonstrate turbulent flow patterns, and provide unreliable velocity measurements—potentially leading to misdiagnosis or inappropriate management decisions. The guidelines emphasize that PDUS "is of particular benefit in a patient with NIP who is being considered for fistula embolization" specifically because it allows proper communication between urologist and interventional radiologist regarding fistula characteristics 1.
Bottom Line
The ultrasound must be done in the erect state. If the patient's current semi-erections are insufficient for adequate visualization, pharmacologic augmentation should be used to achieve proper diagnostic conditions 1.