Priapism

Priapism is a sustained erection that lasts for more than four hours and continues hours beyond or is unrelated to sexual stimulation. It is classified into ischemic (low-flow) priapism and nonischemic (high-flow) priapism. Ischemic priapism is caused by inadequate venous outflow from the corpus cavernosum and results in painful penile ischemia. In adults, ischemic priapism is often idiopathic or an adverse effect of treatments for erectile dysfunction, while sickle cell disease is the most common cause in children. Nonischemic priapism is less common and is caused by increased arterial inflow to the corpus cavernosum, usually due to fistula formation following perineal trauma. Nonischemic priapism is not associated with penile ischemia and is painless. Diagnosis is performed with corporal blood gas analysis to distinguish between ischemic and nonischemic priapism. Blood flow assessment with Doppler ultrasound is used when results of corporal blood gas analysis are indeterminate. Ischemic priapism is a urological emergency requiring immediate therapeutic corporal aspiration and intracavernosal alpha-adrenergic injection. Surgery is indicated if priapism does not subside. Delay in treatment of ischemic priapism is associated with high rates of permanent erectile dysfunction. Nonischemic priapism often self-resolves; initial management is observation.

Ischemic vs. nonischemic priapism

Management approach for suspected priapism ^[2][3][4]

If ischemic priapism is suspected, consult urology early, as prompt treatment is required to preserve tissue function.

Clinical evaluation

Include medication review, sexual history, past surgical history, and evaluation for genital and perineal trauma.

• Symptoms > 4 hours: Manage as priapism.
• Symptoms ≤ 4 hours: Consult urology for the optimal type and timing of intervention for prolonged erection. ^[3][4]

Initial diagnostics

• Clear clinical diagnosis of ischemic priapism: Manage as ischemic priapism.
• All other patients: Obtain diagnostics to distinguish ischemic priapism from nonischemic priapism.
  • Perform penile block and diagnostic corporal aspiration to obtain corporal blood gas analysis.
  • Consider penile and perineal Doppler ultrasound if corporal blood gas analysis is indeterminate.

Management

• Ischemic priapism
  • Perform immediate nonsurgical management of ischemic priapism (e.g., therapeutic corporal aspiration, irrigation, intracavernosal phenylephrine).
  • Obtain further diagnostics for the underlying cause.
  • Expedite surgery if priapism persists despite nonsurgical management.
• Nonischemic priapism: conservative management

• Priapism: a penile erection lasting > 4 hours that continues hours beyond or is unrelated to sexual stimulation ^[3]
• Prolonged erection: an erection that lasts longer than desired but has a duration ≤ 4 hours ^[3]

Initial investigations

• Goal: distinguish between ischemic priapism and non-ischemic priapism
• Corporal blood gas analysis ^[3]
  • Blood gas analysis of a sample from the corpus cavernosum
  • Primary test in all patients presenting with acute priapism of unknown etiology
  • Obtained via diagnostic corporal aspiration
• Penile and perineal Doppler ultrasound ^[3][4]
  • Noninvasive evaluation of penile blood flow
  • Adjunctive test performed under urology guidance if results of corporal blood gas analysis are indeterminate
  • May help assess fistula location and size in nonischemic priapism ^[4]
• Findings
  • See “Diagnosis of ischemic priapism.”
  • See “Diagnosis of nonischemic priapism.”

Corporal blood gas analysis can be deferred if a clinical diagnosis of ischemic priapism is already clear. ^[3][4]

Penile and perineal Doppler does not replace corporal blood gas analysis.

Additional investigations ^[3][4]

Additional investigations may be considered to evaluate the cause of ischemic priapism but must not delay treatment.

• CBC: in all patients
• Reticulocyte count: in patients with vaso-occlusive crisis
• Urine toxicology: based on clinical suspicion
• Testing for sickle cell disease (e.g., hemoglobin electrophoresis): based on clinical suspicion

Ischemic priapism is a urological emergency that needs treatment as soon as possible. Tissue damage can occur as early as 6 hours from onset. ^[1][3][3]

Epidemiology

• Accounts for 95% of all priapism episodes ^[1][3]
• Two peak ages related to the most common cause in each age group (See “Etiology.”) ^[5]
  • Adults: 20–50 years
  • Children 5–10 years

Etiology ^[1][2][6]

• Idiopathic (most common in adults)
• Treatment of erectile dysfunction (common cause in adults)
  • Intracavernous injection therapy (e.g., with alprostadil)
  • Phosphodiesterase type 5 inhibitors (e.g., sildenafil)
• Other medications and substances
  • Antidepressants (e.g., trazodone)
  • Alpha blockers (e.g., prazosin)
  • Antipsychotics
  • Recreational drugs: alcohol, cocaine, cannabis
• Hematological conditions
  • Sickle cell disease; (most common cause in children): Sickled erythrocytes obstruct venous drainage from the corpus cavernosum.
  • Leukemia: leukostasis syndrome
  • Thalassemia
• Autonomic dysfunction: due to autonomic neuropathy or spinal cord dysfunction
• Pelvic tumors: e.g., bladder cancer, prostate cancer

Treatment of erectile dysfunction is a common cause of ischemic priapism in adults, while sickle cell disease is the most common cause in children. ^[2]

Pathophysiology ^[1][7]

• Inadequate venous outflow from the corpus cavernosum as a result of:
  • Thrombosis and/or compression of the penile, prostatic, and/or pelvic veins
  • Prolonged tumescence
• Decreased venous outflow → increased intracavernosal pressure → decreased arterial inflow → penile ischemia

Prolonged penile ischemia can lead to cavernous body fibrosis with irreversible erectile dysfunction. ^[1][7]

Clinical features ^[1][8]

• Early presentation: painful erection
  • Fully erect, rigid, and tender corpus cavernosum
  • Flaccid or partially engorged glans and corpus spongiosum
• Late presentation: color change (e.g., erythema), gangrene
• Recurrent ischemic (stuttering) priapism: generally rare ^[9]
  • Repeated painful erections interspersed with periods of detumescence
  • Most common in individuals with sickle cell disease

Signs of pelvic or perineal trauma suggest nonischemic priapism rather than ischemic priapism. ^[3]

Diagnosis of ischemic priapism ^[3]

• Clinical diagnosis: can be made if classic clinical features and defining criteria for priapism are present alongside a highly suggestive history
• Confirmatory diagnostic findings
  • Corporal blood gas analysis (room air): pO₂ < 30 mmHg; pCO₂ > 60 mmHg; pH < 7.25 ^[3]
  • Penile and perineal Doppler: low blood flow
  • See “Diagnosis of priapism” for approach and additional tests.

Management ^[1][2][3]

Approach

• Follow management approach for suspected priapism, including urgent urology consult.
• Once the diagnosis of ischemic priapism is established, immediately proceed to nonsurgical management.
  • If detumescence is achieved, consider discharge with close follow-up.
  • If detumescence is not achieved, proceed to surgery.
• Manage the underlying cause (see “Etiology”).
  • Discontinue trigger medications.
  • Patients with sickle cell disease ^[1][4]
    • Consult hematology.
    • Begin acute management for sickle cell disease complications (e.g., O2 therapy, hydration).
    • Do not delay treatment of ischemic priapism to perform exchange transfusion.

For stuttering priapism, the management of each acute episode is similar to the management of acute ischemic priapism. ^[2][4]

Nonsurgical management of ischemic priapism ^{[2][3][6][10]}

Therapeutic corporal aspiration, corporal irrigation, and intracavernosal alpha-adrenergic injection are often used in combination to treat acute ischemic priapism. Specific recommendations vary by region. Follow local protocols and consult a urologist.

• Regional anesthesia: penile block
• Needle insertion into the corpus cavernosum ^[11]
  • Prepubescent children: 23-gauge to 21-gauge butterfly needle
  • Adolescents and adults: 19-gauge butterfly needle
  • Technique
    • Insertion site: base of the penile shaft at 3 or 9 o’clock in the lithotomy position
    • Insert the butterfly needle as lateral to the skin as possible.
    • Observe for blood flashback (may be discolored due to deoxygenated hemoglobin).
    • Secure to the skin as needed once properly placed.
• Corporal aspiration
  • Diagnostic corporal aspiration
    • Goal: Obtain blood for corporal blood gas analysis, if indicated.
    • Technique: Aspirate 0.5–3 mL of cavernosal blood into a heparinized syringe.
  • Therapeutic corporal aspiration
    • Goals: remove trapped, deoxygenated blood from corpus cavernosum, relieve pain, restore normal blood flow
    • Technique: Aspirate cavernosal blood in 5 mL increments until bright red blood is consistently observed. ^[6]
• Corporal irrigation (optional): may be performed following therapeutic corporeal aspiration ^[2]
  • Goals: clear coagulated or stagnant blood and encourage normal blood flow ^[11]
  • Technique: Flush (i.e., inject and remove) the corpus cavernosum with 10–20 mL of 0.9% normal saline. ^[10]
• Intracavernosal alpha-adrenergic injection
  • Goals: reduce arterial inflow, encourage detumescence and venous outflow
  • Technique
    • Inject alpha-adrenergic agent, e.g., phenylephrine (off-label)
    • Monitor blood pressure and heart rate during injection.

Ischemic priapism of < 24 hours' duration is typically managed with repeated rounds of aspiration (± irrigation) and intracavernosal phenylephrine over at least 1 hour before surgical intervention is considered. ^[11][12]

Surgical management ^[2][3][6]

• Indication: persistent priapism despite nonsurgical intervention ^[2][3]
• Procedures
  • Corpoglandular shunting: initial procedure in most patients ^[3]
  • Penile prosthesis implantation: considered if shunting fails or for priapism lasting more than 24–48 hours

Prognosis ^[3][13]

• Prognosis depends primarily on the duration of priapism before effective treatment.
• Ischemic priapism lasting > 24 hours: high likelihood of permanent erectile dysfunction

Epidemiology

• Accounts for 5% of priapism episodes ^[2]
• Can occur at any age ^[5]

Etiology ^[14]

• Blunt perineal trauma (e.g., saddle injury) and/or penetrating injury (e.g., local penile injections)
• Congenital vascular malformations

Pathophysiology ^[2]

• Injury to the cavernosal artery → fistula between the cavernosal artery and corpus cavernosum → excessive arterial influx → persistent erection
• No penile ischemia
• Venous drainage is intact.

Clinical features ^[2][15]

• Onset may be delayed up to several weeks after injury.
• Typically painless
• The corpus cavernosum is not fully rigid.
• Symptoms of perineal trauma: perineal swelling, hematuria, dysuria

Diagnosis of nonischemic priapism

• Corporal blood gas analysis: pO₂ > 90 mmHg; pCO₂ < 40 mmHg; pH ∼ 7.4 ^[4]
• Penile or perineal Doppler: high blood flow
• See “Diagnosis of priapism” for additional tests.

Corporal blood gas analysis findings in nonischemic priapism are similar to those in arterial blood gas analysis. ^[4]

Management ^[2][4]

Follow management approach for suspected priapism. Once the diagnosis of nonischemic priapism is confirmed, management is not urgent.

• Discharge home for conservative management.
  • Monitor for resolution for 4 weeks. ^[2][4]
  • Consider applying ice or direct perineal compression. ^[15][16]
• If priapism persists, consult urology to evaluate for arterial embolization.

Prognosis ^[2][15]

• Nonischemic priapism often self-resolves.
• Up to one-third of patients experience some degree of erectile dysfunction following resolution of priapism.

• Urgently evaluate any patient with an abnormal or prolonged erection.
• Manage symptoms lasting > 4 hours as priapism.
• Consult urology urgently for all patients, irrespective of symptom duration.
• Screen for underlying causes.
  • Medication review (e.g., intracavernous injection therapy, sildenafil, prazosin, trazodone)
  • Past medical history (e.g., sickle cell disease, autonomic dysfunction, penile or perineal trauma)
• Consider penile block early for patients with significant pain who require penile needle insertion.
• Distinguish between ischemic and nonischemic priapism.
  • If ischemic priapism cannot be diagnosed clinically, perform diagnostic corporal aspiration and corporal blood gas analysis.
  • Consider penile and perineal Doppler if corporal blood gas analysis is inconclusive.
• If diagnosis of nonischemic priapism is likely, begin conservative management.
• If diagnosis of ischemic priapism is likely, begin nonsurgical management of ischemic priapism.
• Following urology guidance and local protocols, consider the following in combination or sequentially to achieve detumescence in ischemic priapism:
  • Therapeutic corporal aspiration
  • Corporal irrigation
  • Intracavernosal alpha-adrenergic injection
• Expedite surgery if nonsurgical management of ischemic priapism is ineffective.