Priapism

Basics

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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