Priapism

Background
Penis anatomy
  • Sustained (> 4h) erection not associated with sexual stimulation
  • May lead to erectile dysfunction and penile necrosis
  • High rate of sexual dysfunction if present > 24hrs

Types

High-flow (nonischemic)
  • Rare
  • Usually painless
  • Increased arterial flow
  • Usually self-resolves and does not require intervention
  • Usually does not cause ischemia or sexual dysfunction

Low-flow (ischemic)
  • Most common type
  • Veno-occlusion causing pooling of deoxygenated blood in cavernous tissue
  • Painful
  • Urologic emergency
    • May progress to ischemia and necrosis without intervention

Causes
  • High-flow
    • Arterio-cavernosal shunt due to groin or straddle injury
    • High spinal injury

Clinical Features

Low-flow
  • Pain
  • Rigid penile shaft (corpus cavernosum)
  • Flaccid penile glans and spongiosum

High-flow
  • Painless
  • Partially rigid shaft
  • Rigid penile glans

Differential Diagnosis
  • Peyronie's Disease
  • Urethral foreign body
  • Penile surgical implant
  • Erection from sexual arousal

Non-Traumatic penile diagnoses

Penile trauma

Evaluation
  • CBC
    • Consideration of leukemia or undiagnosed sickle cell disease
  • Type and screen
    • May require exchange transfusion in sickle cell disease
  • Coagulation profile
  • Consider urinalysis/toxicologic screen if unclear etiology
  • Cavernosal blood gas may help differentiate high- from low-flow
    • Low flow causes hypoxic, hypercarbic, and acidotic cavernosal blood gases
      • pH < 7.25, pO2 < 30 mmHg, pCO2 > 60 mmHg
  • Ultrasound may help distinguish high- from low-flow

Management

Low Flow Priapism

Follow a step-wise approach:

  • 1. Aspirate 25mL of blood from cavernosum, up to two times
  • 2. Irrigate cavernosum with 25mL of cold (10°C) saline
  • 3. Medication injections

Aspiration of corpus cavernosum
  • Ensure procedure is appropriate
    • Rarely beneficial after 48h
    • Risk of impotence is high even with treatment
  • Obtain consent
  • Prep the area with chlorhexidine and drape appropriately
  • Penile nerve block or local anesthesic at puncture site
  • Insert 18 gauge needle into penile shaft at 2 and 10 o'clock positions (or 3 and 9 o'clock positions)
  • Aspirate blood (usually 20 - 30 cc on each side)
  • May follow with intracavernosal injections (most common is phenylephrine)

α/β-2 Agonist
  1. Consider terbutaline[4]
    • Dose: 0.25-0.5mg SQ in deltoids OR 5-10mg PO, may repeat in q20min
  2. Phenylephrine
    • Dilute phenylephrine 1ml of 1mg/ml in 9mL NS for final concentration of 100mcg/mL
      • For 500 mcg/ml, take 0.5 ml of 10mg/ml phenylephrine, and dilute in 9.5 cc NS
    • Inject base of penis with 19-Ga needle (after blood aspiration to confirm position)
      • 100-200 mcg every 3-5min (max 1000 mcg) until resolution or 1 hour
    • Ensure patient fully monitored, with BP, HR, pulse oximetry
      • Reflex bradycardia is expected, so consider dosages relative to toleration of drop from baseline HR
      • Only one side needs to be injected since there exists a vascular channel between the 2 corpora cavernosa
    • Compress injection area to prevent hematoma formation
    • Use with caution in cardiovascular disease
  3. Epinephrine
    • In pediatric population, intracavernosal injection of epinephrine instead of phenylephrine has been shown more successful in achieving detumescence

Wrap penis in elastic bandage after detumescence is achieved

High Flow Priapism
  • May resolve with observation
  • Consult urology for consideration of surgical correction or embolization by interventional radiology[5]

Sickle Cell Disease
  • IV hydration
  • Pain control
  • Supplemental oxygen
  • Transfusion for goal HCT>30% with consultation for partial exchange transfusion (HGB-S<30%)
    • Exchange transfusion is associated with ASPEN syndrome (Association of Sickle cell Priapism, Exchange transfusion & Neurological events)
  • Urology consult

Disposition
  • Admit if refractory to treatment or need or IR or surgical intervention
  • May discharge home if treatment is successful with close follow-up by urology

Video

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References
  1. Miller ST, Rao SP, Dunn EK, Glassberg KI. Priapism in children with sickle cell disease. J Urol. Aug 1995;154(2 Patient 2):844-7
  2. reen J, Hakim L. Cocaine-induced veno-occlusive priapism: importance of urine toxicology screening in the emergency room setting. Clin Urol. 1999;161
  3. Quan D, Ruha AM. Priapism associated with Latrodectus mactans envenomation. Am J Emerg Med. Jul 2009;27(6):759.e1-2
  4. Lowe FC, Jarow JP. Placebo-controlled study of oral terbutaline and pseudoephedrine in management of prostaglandin E1-induced prolonged erections. Urology. Jul 1993;42(1):51-3
  5. Sandro C. High-flow priapism: treatment and long-term follow-up. 2002. 59(1).110–113 PDF
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