What causes priapism?

Causes of Priapism

Priapism results from failure of the normal penile detumescence mechanism, with causes broadly categorized by priapism subtype: ischemic (veno-occlusive), non-ischemic (arterial), and stuttering (recurrent ischemic). 1

Ischemic (Low-Flow) Priapism Causes

Ischemic priapism accounts for approximately 95% of all priapism cases and results from venous outflow obstruction causing blood stagnation in the corpora cavernosa. 1, 2

Medication-Induced Causes

• Intracavernosal injection therapy (papaverine, alprostadil) causes prolonged smooth muscle relaxation that prevents normal venous compression, representing the most common iatrogenic cause. 1
• Phosphodiesterase-5 inhibitors (sildenafil, tadalafil) disrupt the balance between vasorelaxing and vasoconstrictive factors, though the exact mechanism is not fully understood. 1, 3, 4
• Antipsychotic medications and antidepressants (including SSRIs like paroxetine) can trigger priapism through alpha-adrenergic blockade or serotonergic mechanisms. 5, 6

Hematologic Disorders

• Sickle cell disease or trait is a critical underlying cause, with patients requiring both urologic and hematologic management. 5, 7
• Thalassemia, leukemia, and other blood dyscrasias predispose to priapism through altered blood viscosity and vascular occlusion. 5
• Multiple myeloma represents another hematologic condition that may predispose to priapism. 4

Anatomical Predispositions

• Anatomical deformation of the penis (angulation, cavernosal fibrosis, Peyronie's disease) increases priapism risk. 4

Non-Ischemic (High-Flow) Priapism Causes

Non-ischemic priapism accounts for approximately 5% of cases and results from unregulated arterial inflow into the corpora cavernosa. 1, 2

Traumatic Causes

• Perineal or penile trauma causes laceration of the cavernous artery, creating an abnormal arterio-cavernosal fistula with persistent arterial flow. 1, 8
• Blunt perineal trauma is the most common mechanism for high-flow priapism. 2

Stuttering (Recurrent Ischemic) Priapism Causes

Stuttering priapism represents a recurrent variant of ischemic priapism with the same veno-occlusive pathophysiology, characterized by repetitive, self-limited episodes with intervening periods of complete detumescence. 1

• Sickle cell disease is the most common underlying condition for stuttering priapism. 8
• Previous episodes of ischemic priapism predispose to recurrent events. 5

Critical Diagnostic Considerations

Essential History Elements to Identify Causes

• Drug history must include intracavernosal injection therapy, PDE-5 inhibitors, antipsychotics, antidepressants, and recreational drugs—inadequate drug history leads to missed diagnoses. 5
• Hematologic disorder screening for sickle cell disease/trait, thalassemia, leukemia, or blood dyscrasias is essential. 5
• Trauma history to the perineum or penis suggests non-ischemic etiology. 5
• Previous priapism episodes and their treatments inform current management and suggest stuttering priapism. 5

Physical Examination Findings

• Examine the perineum for signs of trauma, hematoma, or masses suggesting arterial injury. 5
• Palpate the abdomen for masses, organomegaly, or lymphadenopathy suggesting malignancy as an underlying cause. 5

Common Pitfall to Avoid

Do not delay obtaining a complete medication and drug use history—patients must be directly questioned about erectile dysfunction treatments and recreational drug use, as inadequate drug history is a leading cause of missed diagnoses. 5