Priapism

Specialty: Nephrology and urology.

• involuntary prolonged erection
• pathological persistent erection without sexual stimulation

Why it occurs

• Ischemic or low-flow priapism (medical emergency characterized by venous stasis and anoxia of the corpora cavernosa, associated with sickle cell anemia, leukemias or hypercoagulability)
• Intracavernous vasoactive medications (alprostadil, papaverine) or systemic medications (sildenafil, trazodone, typical and atypical antipsychotics)
• Non-ischemic or high-flow priapism (secondary to post-traumatic arterial fistula that pours continuous oxygenated blood into the cavernous lakes, usually painless)
• Metastatic neoplastic invasion of the corpora cavernosa (due to prostate or bladder cancer)
• Bite of poisonous insects or arachnids (such as the banana spider)

Initial workup

Gasometry of blood aspirated from the corpora cavernosa (ischemic priapism shows pH <7.25, pO2 <30 mmHg, pCO2 >60 mmHg; non-ischemic priapism shows bright oxygenated blood with normal pH and arterial gases); duplex Doppler ultrasound of the corpora cavernosa to evaluate the flow of the cavernous arteries; complete blood count and peripheral blood smear (rule out sickle cell disease or leukemia).

Standard management

• Phenylephrine — inject 100-500 mcg intracavernously every 3-5 minutes by specialist, maximum 1 mg; Selective alpha-1 agonist that induces arteriolar vasoconstriction, facilitating venous drainage. Requires continuous monitoring of blood pressure and heart rate to avoid hypertensive crises
• Aspiration of blood from the corpora cavernosa using a 19G needle followed by lavage with warm saline solution
• Aggressive intravenous hydration, oxygen and analgesia in sickle cell crisis.