In a 21‑year‑old man with persistent semi‑erections, glans discoloration, penile numbness, and urinary hesitancy, what findings would be expected on penile Doppler ultrasound?

Penile Doppler Ultrasound Findings in Non-Ischemic Priapism

In this 21-year-old man with persistent semi-erections, glans discoloration, penile numbness, and urinary hesitancy, penile Doppler ultrasound would most likely reveal a cavernous artery fistula with turbulent flow, normal to high peak systolic velocities in the cavernous arteries, and possibly a pseudoaneurysm—findings consistent with non-ischemic (high-flow) priapism, likely post-traumatic. 1

Key Ultrasound Findings Expected

Primary Findings in Non-Ischemic Priapism

The clinical presentation—persistent semi-erection (not fully rigid), lack of severe pain, and prolonged duration—strongly suggests non-ischemic priapism rather than the emergency ischemic type. 1, 2

Penile duplex Doppler ultrasound (PDUS) would demonstrate:

• Cavernous artery fistula with detectable turbulent flow at the site of arteriovenous communication 1
• Normal to high velocities in the cavernous arteries (contrasting sharply with ischemic priapism where flow is minimal or absent) 1
• Pseudoaneurysm may be visible as a cavity or dilation in the cavernous artery 3
• Fully oxygenated blood flow patterns consistent with arterial blood rather than the stagnant, hypoxic flow of ischemic priapism 1

Scanning Technique Specifics

The ultrasound should be performed with the patient in lithotomy or frog-leg position, scanning:

1. Perineum first (where traumatic fistulas often originate)
2. Entire penile shaft to map the full extent of vascular abnormalities 1

The examination must be done in the erect/tumescent state to properly visualize the fistula and abnormal flow patterns. 1

Clinical Context and Differential Diagnosis

Why This is Non-Ischemic Priapism

The presentation differs markedly from acute ischemic priapism:

• Semi-erections (partial tumescence) rather than fully rigid corpora 2
• Glans discoloration and numbness suggest vascular compromise but not the severe pain typical of ischemic priapism
• Prolonged duration (weeks) without progression to complete rigidity 1

In ischemic priapism, ultrasound would instead show little or no cavernous blood flow with corporal blood gas showing PO2 <30 mmHg, PCO2 >60 mmHg, and pH <7.25. 2 This patient's presentation doesn't fit that emergency pattern.

Likely Etiology

Given the patient's age and presentation, post-traumatic arterial injury is the most probable cause. Even without recalled perineal trauma, straddle injuries or blunt trauma can create arteriovenous fistulas that present with delayed high-flow priapism. 1, 3

Diagnostic Value and Next Steps

Ultrasound Performance

PDUS has demonstrated 40-100% sensitivity and 73% specificity compared to pudendal artery angiography for localizing vascular injuries and anatomical abnormalities. 4 It serves as a reliable alternative to blood gas analysis when differentiating high-flow from low-flow priapism. 4

Critical Pitfall to Avoid

Do not treat this as an emergency requiring immediate intervention. Non-ischemic priapism is not a medical emergency unlike ischemic priapism. 1 The ultrasound can be performed non-urgently by an experienced ultrasound urologist or radiologist. 1

Management Implications

If PDUS confirms a persistent fistula after observation:

• The fistula location and size guide potential selective embolization (first-line therapy if patient desires treatment) 1
• The ultrasound provides roadmap for interventional radiology, with embolization achieving detumescence in 85% of cases 1
• Follow-up PDUS after treatment confirms fistula closure or identifies recurrence 3

The urinary hesitancy and numbness warrant additional evaluation for potential pelvic/perineal nerve involvement, but the ultrasound findings will primarily address the vascular etiology of the persistent erection.