Physiology and Treatment of Priapism

Pathophysiology and Diagnosis

Blood gas analysis in ischemic priapism shows low oxygen levels (pO₂ <30 mmHg), high carbon dioxide levels (pCO₂ >60 mmHg), and low pH (<7.25), reflecting tissue ischemia 1
Non-ischemic priapism is characterized by unregulated arterial inflow with normal venous outflow, maintaining erection, and arteriovenous fistula formation can create abnormal blood flow patterns 2

For iatrogenic prolonged erections (<4 hours), intracavernosal phenylephrine is highly effective, and oral sympathomimetics (midodrine, pseudoephedrine) have modest efficacy, with midodrine showing 36-41% success versus 12-15% placebo 3, 4
For ischemic priapism (>4 hours), immediate phenylephrine injection (100-500 mcg intracavernosal) is first-line treatment, and aspiration and irrigation can mechanically remove hypoxic blood and restore normal metabolism 1
Time-dependent tissue damage occurs in ischemic priapism, with minimal damage if treated within 12 hours, but widespread necrosis after 24-48 hours 1, 5