Priapism – Causes, Symptoms, Diagnosis, Treatment and Ongoing care

Basics

Description

  • Penile erection that lasts for >4 hours and is unrelated to sexual stimulation or excitement
  • Classified into ischemic and nonischemic variants
  • Ischemic (low-flow) priapism is painful and requires urgent clinical intervention.
  • Stuttering priapism is recurrent ischemic priapism over an extended period.
  • Nonischemic (high-flow) priapism could be related to prior trauma and does not require urgent treatment.
  • System(s) affected: Reproductive

Pediatric Considerations

In children, nearly all priapism is caused either by sickle cell anemia or trauma (1).

Epidemiology

Incidence

In the Netherlands, 1.5 cases of ischemic priapism per 100,000 person-years in the general male population (data not available for the US) (1). After exclusion of cases associated with intracavernous vasoactive drug use, incidence is 0.9 cases per 100,000 person-years (2).

Risk Factors

  • Sickle cell anemia, lifetime risk of ischemic priapism 29–42% (1)
  • Dehydration

General Prevention

  • Avoid dehydration.
  • Avoid excessive sexual stimulation.
  • Avoid causative drugs (see Causes) when possible.
  • Avoid genital and pelvic trauma.

Pathophysiology

  • In ischemic priapism, decreased venous outflow results in increased intracavernosal pressure. This leads to erection, decreased arterial inflow, stasis of blood, local hypoxia, and acidosis (a compartment syndrome). Eventually penile tissue necrosis and fibrosis may occur. The exact mechanism is unknown and may involve trapping of erythrocytes in the veins draining the erectile bodies.
  • In nonischemic priapism, increased arterial flow without decreased venous outflow. There is increased inflow and outflow, which results in a sustained, nonpainful, partially rigid erection.
  • Aberrations in the phosphodiesterase (PDE-5A) pathway has been proven in mice to be one mechanism of priapism (3).

Etiology

  • Ischemic priapism:
    • Idiopathic, estimated to about 50% (1)
    • Intracavernosal injections of vasoactive drugs for erectile dysfunction
    • Oral agents for erectile dysfunction
    • Pelvic vascular thrombosis
    • Prolonged sexual activity
    • Sickle cell disease and trait
    • Leukemia from infiltration of the corpora
    • Other blood dyscrasias (G6PD deficiency, thrombophilia)
    • Pelvic hematoma or neoplasia (penis, urethra, bladder, prostate, kidney, rectal)
    • Cerebrospinal tumors
    • Asplenism
    • Fabry disease
    • Tertiary syphilis
    • Total parenteral nutrition, especially 20% lipid infusion (results in hyperviscosity)
    • Bladder calculus
    • Trauma to penis
    • Urinary tract infections, especially prostatitis, urethritis, cystitis
    • Several drugs suspected as causing priapism (e.g., chlorpromazine, prazosin, cocaine, trazodone, and some corticosteroids; anticoagulants (heparin and Coumadin); phosphodiesterase inhibitors (Viagra, others); testosterone; immunosuppressants (tacrolimus); and antihypertensives (hydralazine, propranolol, guanethidine)
    • Intracavernous fat emulsion
    • Hyperosmolar intravenous contrast
    • Spinal cord injury
    • General or spinal anesthesia
    • Heavy alcohol intake or cocaine use
  • Nonischemic priapism:
    • The most common cause is penile or perineal trauma resulting in a fistula between cavernous artery and the corpora.
    • Rarely, iatrogenic causes for the management of ischemic priapism can result in nonischemic priapism.
    • Certain urological surgeries have also resulted in nonischemic priapism.

Commonly Associated Conditions

  • Sickle cell anemia
  • G6PD deficiency
  • Leukemia
  • Neoplasm

Diagnosis

History

  • Penile erection that is persistent, prolonged, painful, and tender (ischemic)
  • Duration of erection, degree of pain
  • Perineal or penile trauma
  • Prior episodes of priapism
  • Urination difficult during erection
  • History of any hematological abnormalities
  • Cardiovascular disease
  • Medications
  • Recreational drugs
  • Loss of erectile function if treatment is not prompt and effective

Physical Exam

  • Ischemic priapism:
    • Penis is fully erect, corpora cavernosa are rigid and tender, and corpora spongiosum and glans are flaccid. Usually associated with tenderness and pain.
  • Nonischemic priapism:
    • Penis is partially erect, and the corpora cavernosa are semirigid and nontender, with the glans and corpora spongiosum flaccid. Usually not tender or painful.
  • Perineum, abdomen, and lymph node exam also valuable to rule out underlying condition
  • Complete penile and scrotal exam necessary. Determine if penile prosthesis is present.

Diagnostic Tests & Interpretation

Lab

  • Complete blood chemistry with reticulocyte count to detect leukemia or platelet abnormalities
  • Sickling hemoglobin (Hgb) solubility test and Hgb electrophoresis
  • Coagulation profile
  • Platelet count
  • Urinalysis
  • Urine toxicology if illicit drugs suspected
  • Corporal blood gas can be used to distinguish ischemic from nonischemic priapism.

Imaging

  • Color duplex ultrasound of the penis and perineum may be necessary to differentiate ischemic from nonischemic priapism. In ischemic priapism, there is no blood flow in the cavernosal arteries, whereas in nonischemic patients there is high blood flow (1); may also see fistulas or pseudoaneurysms suggestive of nonischemic.
  • Penile arteriography can be used to identify presence and site of fistulas in patients with nonischemic priapism.

Diagnostic Procedures/Surgery

Physical exam is usually able to distinguish ischemic from nonischemic priapism.

Pathological Findings

  • Pelvic vascular thrombosis
  • Partial thrombosis of corpora cavernosa of the penis
  • Corpus spongiosum, glans penis: No involvement
  • Arterial priapism will show arteriocavernous fistula.

Treatment

  • Ischemic priapism requires immediate treatment in order to preserve future erectile function (a longer delay in treatment means higher chance of future impotence):
    • Cavernosal aspiration with irrigation (success rate ∼30%) (1,4)
    • Cavernosal injection of phenylephrine (α adrenergic sympathomimetic) with monitoring of patient’s blood pressure and pulse (success rate ∼65 %) (4). Inject every 5–10 minutes until detumescence.
    • Continue aspiration, irrigation, and phenylephrine for several hours. If this fails, shunt procedures are considered (first a distal shunt).
  • Nonischemic priapism:
    • Initial observation
    • If this fails, arteriography and embolization with absorbable materials (5% rate of impotence versus 39% with permanent materials) or surgical ligation as a last resort (4)
  • Treat underlying condition (i.e., sickle cell disease). Do not delay intracavernous treatment.

Medication

  • Narcotics for pain if needed
  • Pseudoephedrine is not recommended by the American Urological Association (4):
    • Efficacy is reported in nonrandomized studies as 28–36% (1).
    • No randomized studies have been conducted to date.
  • Terbutaline has been studied and may be effective (uncontrolled trials showed a 65% resolution rate) for priapism caused by self-injection of agents to treat erectile dysfunction (4).
  • For stuttering priapism, a trial of GnRH agonists or antiandrogens is effective; self-injection of phenylephrine is also effective.
  • PDE-5 inhibitors also have a role in the prevention of priapism in patients suffering from stuttering priapism (5).

Additional Treatment

General Measures

  • Reassure patient about outcome if warranted.
  • Continuous caudal or spinal anesthesia if etiology is neurogenic.
  • Treat any underlying cause.
  • In sickle cell anemia: IV hydration; partial exchange or repeated transfusions to reduce percentage of sickle to <50%
  • Relieve patient’s pain.

Issues for Referral

A urologist should be consulted in all cases of suspected priapism to ensure highest likelihood of preserved erectile function.

Surgery/Other Procedures

  • Introduction of 18- or 19-gauge needle into corpora cavernosa (best done by urologist if available) at 9 o’clock and 3 o’clock positions with aspiration of 20–30 mL of blood from corpus cavernosum. May follow with intracavernous injection of 100–500 mcg phenylephrine. (To make 200 mcg phenylephrine, add 0.2 mL of 1% phenylephrine in 9.8 cc of normal saline.) If this fails, consider shunts.
  • Distal shunt:
    • Winter shunt: Biopsy needle inserted in glans penis to create shunt between glans and corpora
    • Al-Ghorab shunt: Excision of tunica albuginea
  • Proximal shunts

Ongoing Care

Follow-Up Recommendations

Bed rest until priapism resolves

Patient Monitoring

Close follow-up with a urologist is required after surgical treatments for priapism.

Patient Education

  • Information about long-term outlook, referral for counseling
  • Reduction of vasoactive drug therapy if responsible for priapism and elimination of offending drugs if causal

Prognosis

  • Even with excellent treatment for a prolonged priapism, detumescence may require several weeks secondary to edema (1)
  • Impotence is likely in ischemic priapism and is up to 90% if the priapism lasts longer than 24 hours.
  • Despite early intervention, ischemic priapism is likely to result in impotence in up to 50% of men.

Complications

Erectile dysfunction (i.e., impotence)

References

1. Huang YC, Harraz AM, Shindel AW, et al. Evaluation and management of priapism: 2009 update. Nat Rev Urol. 2009;6:262–71.

2. Eland IA, van der Lei J, Stricker BH, et al. Incidence of priapism in the general population. Urology. 2001;57:970–2.

3. Champion HC, Bivalacqua TJ, Takimoto E, et al. Phosphodiesterase-5A dysregulation in penile erectile tissue is a mechanism of priapism. Proc Natl Acad Sci U S A. 2005;102:1661–6.

4. Montague DK, Jarow J, Broderick GA, et al. American Urological Association guideline on the management of priapism. J Urol. 2003;170:1318–24.

5. Muneer A, Minhas S, Arya M, et al. Stuttering priapism – a review of the therapeutic options. Int J Clin Pract. 2008.

Additional Reading

Burnett AL. Pathophysiology of priapism: dysregulatory erection physiology thesis. J Urol. 2003;170:26–34.

Pryor J, Akkus E, Alter G, et al. Priapism. J Sex Med. 2004;1:116–20.

See Also (Topic, Algorithm, Electronic Media Element)

Anemia, Sickle Cell; Erectile Dysfunction

Codes

ICD9

607.3 Priapism

Snomed

6273006 Priapism (disorder)

Clinical Pearls

  • Priapism is a prolonged penile erection that lasts longer than 4 hours and is unrelated to sexual stimulation.
  • In evaluating priapism, the clinician must distinguish ischemic from nonischemic priapism by history and physical, as well as blood gas and possibly ultrasound, if needed.
  • Ischemic priapism is an emergent condition that requires immediate urological evaluation and treatment.
  • The most common causes of ischemic priapism are idiopathic, related to treatments for erectile dysfunction, or related to use of substances (medicinal or recreational).
  • If an underlying medical condition is identified (sickle cell anemia), proper concomitant treatment is necessary to increase efficacy of treatment.

Jean-Paul Marat

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