Priapism is a persistent (eg, >4 hr), painful erection. It is characterized by impaired outflow from the corpora cavernosa, leading to acidosis, anoxia, and tissue ischemia. Priapism is a medical emergency that can lead to irreversible ischemic injury if not corrected promptly. Common risk factors for ischemic (low-flow) priapism include phosphodiesterase-5 inhibitors (eg, sildenafil), intracavernosal injections (eg, alprostadil), certain medications (eg, trazodone), and sickle cell disease.
The diagnosis of ischemic priapism can be confirmed by blood gas analysis of a corporeal aspirate. At the onset of symptoms, priapism may be terminated with simple interventions (eg, urination, cold compresses), but symptoms lasting >4 hours require invasive treatment (Choice E). Aspiration of the corpora cavernosa (often followed by irrigation with cold saline) is advised, with intracavernosal injection of an alpha agonist (eg, phenylephrine) if aspiration does not rapidly relieve the symptoms.