Priapism (Low-Flow/Ischemic)

Ischemic Priapism: An Overview and Management

Ischemic priapism is a urological emergency that requires prompt diagnosis and treatment to prevent long-term complications, most notably erectile dysfunction.¹˒² It can occur in males of any age, including children, particularly those with sickle cell disease, which is the most common associated diagnosis in pediatric cases.¹˒²

Clinical Presentation

Patients typically present with a painful, rigid erection lasting longer than four hours, unrelated to sexual stimulation.¹ The penile shaft is firm, but the glans is usually soft and uninvolved.²

Etiology

The causes of ischemic priapism are diverse and can include:²

• Blood disorders: Sickle cell disease (most common in children), leukemia, thalassemia, multiple myeloma.

• Prescription medications: Certain antidepressants (e.g., trazodone), antipsychotics, alpha-blockers, medications for erectile dysfunction (especially intracavernosal injections like alprostadil, papaverine, phentolamine), anticoagulants, and some ADHD medications.

• Substance use: Alcohol, cocaine, marijuana, and other illicit drugs.

• Trauma: Though less common for ischemic priapism compared to high-flow, pelvic or perineal trauma can sometimes be a factor.

• Other conditions: Metabolic disorders (e.g., gout, amyloidosis), neurogenic disorders (e.g., spinal cord injury), and cancers involving the penis.

Pathophysiology

Ischemic priapism is a disorder of venous outflow or stasis.² The failure of detumescence mechanisms leads to trapped, deoxygenated blood within the corpora cavernosa. This results in a compartment syndrome with increasing hypoxia, hypercarbia, and acidosis within the cavernosal tissue. If prolonged (typically beyond 4-6 hours), this ischemic environment leads to smooth muscle necrosis, fibrosis, and ultimately, erectile dysfunction.² Microscopic tissue damage can begin around 6 hours, with permanent structural changes starting after 12 hours, and significant cellular damage and thrombus formation after 24-36 hours.²

Diagnosis

Diagnosis is primarily clinical, based on history and physical examination.² Key diagnostic steps include:

• History: Duration of erection, presence of pain, history of similar episodes (stuttering priapism), underlying medical conditions (e.g., sickle cell disease), medication use, and illicit drug use.

• Physical Examination: Assessment of penile rigidity (corpora cavernosa rigid, glans soft), and signs of trauma or other underlying conditions.

• Cavernosal blood gas analysis: This is crucial to differentiate ischemic from non-ischemic priapism. In ischemic priapism, blood gas values will typically show hypoxia (pO₂ < 30 mmHg), hypercarbia (pCO₂ > 60 mmHg), and acidosis (pH < 7.25).²

• Laboratory tests: Complete blood count (CBC), reticulocyte count, hemoglobin electrophoresis (if sickle cell disease is suspected), and toxicology screen may be indicated based on clinical suspicion.²

• Penile Doppler ultrasonography: Can be used to assess cavernosal blood flow. In ischemic priapism, arterial inflow is typically absent or minimal.²

Treatment/Management

The primary goal of treatment is immediate detumescence to restore normal blood flow and prevent corporal fibrosis and erectile dysfunction.² Treatment should be initiated as soon as possible, ideally within 4-6 hours of onset.

• Initial conservative measures (often insufficient alone): Oral medications like terbutaline or pseudoephedrine have been used but are generally not recommended as sole first-line therapy due to limited efficacy.²

• Aspiration and Irrigation: Corporal aspiration (drawing blood from the corpora cavernosa) is often the first invasive step. This may be followed by irrigation with normal saline.²

• Intracavernosal sympathomimetic injection: If aspiration alone is unsuccessful, injection of a sympathomimetic agent (e.g., phenylephrine) into the corpora cavernosa is the next step. Phenylephrine is preferred due to its relatively selective alpha-1 adrenergic agonist activity, minimizing cardiovascular side effects. It causes contraction of the cavernosal smooth muscle, facilitating venous outflow.² Multiple injections may be necessary.

• Surgical shunting procedures: If conservative measures and sympathomimetic injections fail, or if priapism has been prolonged (e.g., >24-36 hours), surgical intervention is required to create a shunt or fistula to divert blood from the corpora cavernosa. Various shunting techniques exist (e.g., Winter, Ebbehoj, Al-Ghorab, T-shunt, penoscrotal decompression).² The choice of shunt depends on the surgeon’s experience and the clinical situation.

Expected Outcomes & Complications

Prompt treatment (within 4-12 hours) generally leads to a good prognosis for recovery of erectile function.² However, the longer the duration of ischemic priapism, the higher the risk of permanent erectile dysfunction. If priapism lasts longer than 24-36 hours, the likelihood of severe erectile dysfunction is very high, potentially exceeding 90%.² Other complications can include penile fibrosis, penile shortening, and pain.²

Patient Selection Criteria

All patients presenting with an erection lasting more than 4 hours, unrelated to sexual stimulation and painful, should be evaluated for ischemic priapism.²