History and exam

Key diagnostic factors

common

history of current systemic disease

The following have been reported as predisposing to ischemic priapism: sickle cell disease, thalassemia, assorted hematologic dyscrasias, parenteral hyperalimentation, hemodialysis, heparin-induced platelet aggregation, and local primary (penile carcinoma/squamous cell carcinoma, prostatic adenocarcinoma) or metastatic neoplasia (metastases to the penis from prostate, rectosigmoid colon, kidney, urothelial carcinoma of the urinary bladder, chronic myeloid leukemia).[13][14][15][16]

history of vasoactive medication or drug use

Medications implicated include alpha-adrenergic receptor antagonists (prazosin, terazosin, doxazosin, tamsulosin), anti-anxiety agents (hydroxyzine), anticoagulants (heparin, warfarin), antidepressants and antipsychotics (trazodone, bupropion, fluoxetine, sertraline, lithium, clozapine, risperidone, olanzapine, chlorpromazine, thioridazine), and antihypertensives (hydralazine, guanethidine, propranolol).[1][10]

Second-generation antipsychotics (33.8%), other medications (11.3%), and alpha-adrenergic antagonists (8.8%) account for most reported cases of drug-induced priapism.[10]

Alcohol and cocaine may predispose to ischemic priapism.[29][30][31]

prolonged erection of >4 hours' duration

Typical of ischemic and nonischemic priapism.

Episodes <4 hours are more often seen in recurrent (stuttering) priapism.[1]

painful rigid penis

Characteristic of ischemic priapism.[1]

uncommon

penis not fully rigid and not painful

Characteristic of nonischemic priapism.[1][4]

history of perineal or genitourinary trauma

May predispose to nonischemic priapism.[1][4]

Trauma may create an arteriovenous fistula within the penis, leading to excessive arterial inflow.

Risk factors

strong

hemoglobinopathy

In hemoglobinopathies, most importantly sickle cell disease but also thalassemia, venous stasis within the penis as a result of the associated hypercoagulable state is common.

Sickle cell disease is the most common etiology of priapism in childhood, accounting for 65% of cases.[6] Among a large multicenter cohort of patients with sickle cell disease (n=1314), 14.3% of patients had experienced priapism (n=188).[7] The mean age of the first priapism episode was 16 years. Significant predictors of priapism in the cohort included increasing age (51 of 745 males younger than 18 years [6.9%] vs. 137 of 568 males 18 years old or older [24.1%]) and more severe sickle cell disease genotype (e.g., homozygous SS).[7]

In sickle cell disease, most priapism episodes begin during sleep in boys.[27] In a survey of adults with sickle cell disease, 17% of episodes of priapism were related to sexual activity and 3% each were related to excessive ethanol intake or were spontaneous.[28]

vasoactive drugs

Medications implicated include alpha-adrenergic receptor antagonists (prazosin, terazosin, doxazosin, tamsulosin), anti-anxiety agents (hydroxyzine), anticoagulants (heparin, warfarin), antidepressants and antipsychotics (trazodone, bupropion, fluoxetine, sertraline, lithium, clozapine, risperidone, olanzapine, chlorpromazine, thioridazine), and antihypertensives (hydralazine, guanethidine, propranolol).[1][10] 

Second-generation antipsychotics (33.8%), other medications (11.3%), and alpha-adrenergic antagonists (8.8%) account for most reported cases of drug-induced priapism.[10]

Alcohol and cocaine may predispose to ischemic priapism.[29][30][31]

weak

perineal or penile trauma

Major cause of nonischemic priapism (associated with excessive arterial penile inflow).[17][32]

malignancies or local infection

A variety of malignant diseases have been associated with ischemic priapism. These include a local primary (e.g., prostatic adenocarcinoma) or metastatic (e.g., urothelial carcinoma of the urinary bladder or urethra, chronic myeloid leukemia) disease.[16][33]

Rarely, ischemic priapism may be seen in pelvic infection.

spinal cord disease

Injury (e.g., trauma, cauda equina syndrome) or lesions that interfere with penile stimulatory pathways may cause ischemic priapism.

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