• Penile erection (engorgement of corpora cavernosa) in the absence of sexual arousal that is prolonged and frequently painful
  • Low-flow priapism:
    • Most common mechanism
    • Poor venous outflow
    • Usually painful
    • Ischemia and thrombosis from stagnant, hypoxic blood can occur after a few hours
    • Fibrosis and erectile dysfunction are late sequelae
  • High-flow priapism:
    • Rare
    • Penile arterial laceration with uncontrolled inflow of arterial blood
    • Usually painless
    • Presentation may be later than in low-flow priapism
    • Ischemia and erectile dysfunction are uncommon


  • Idiopathic
  • Pharmacologic agents:
    • Intracavernosal injectables for the treatment of erectile dysfunction:
      • Prostaglandin E1
      • Papaverine
      • Phentolamine
    • Psychotropics:
      • Phenothiazines
      • Butyrophenones
      • Trazodone
      • Sedative–hypnotics
      • Selective serotonin uptake inhibitors
    • Antihypertensives:
      • Prazosin
      • Hydralazine
      • Phenoxybenzamine
      • Guanethidine
    • Rarely implicated agents:
      • Phosphodiesterase inhibitors: Sildenafil (Viagra), tadalafil (Cialis), vardenafil (Levitra)
      • Anticoagulants
      • Cocaine
      • Marijuana
      • Ethanol
      • Androstenedione
    • Toxins (Black Widow, scorpion)
  • Hematologic disorders predisposing to sludging of blood:
    • Sickle cell anemia (most common cause)
    • Leukemia
    • Multiple myeloma
    • Polycythemia
  • Penile and perineal trauma (arterial laceration and high-flow priapism)
  • Spinal trauma (loss of inhibitory adrenergic tone)
  • Rare causes:
    • Pelvic neoplasms and infections
    • Infiltrative diseases (e.g., amyloidosis)
    • Dialysis
    • Parenteral nutrition solutions containing a fat emulsion

Pediatric Considerations
Sickle cell anemia is the cause of most priapism in children

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