What is the recommended treatment for priapism using injection therapy?

Recommended Treatment for Priapism Using Injection Therapy

For ischemic priapism, intracavernous injection of phenylephrine (100-500 μg diluted in saline) is the recommended first-line pharmacological treatment, with a maximum dose of 1 mg in an hour. 1

Diagnostic Differentiation

Before initiating treatment, it's critical to differentiate between types of priapism:

• Ischemic (low-flow) priapism:

  • Medical emergency requiring immediate intervention
  • Painful, rigid corpora cavernosa
  • Blood gas analysis: PO₂ ≤30 mmHg, PCO₂ ≥60 mmHg, pH <7.25 1

• Non-ischemic (high-flow) priapism:

  • Not a medical emergency
  • Usually painless, tumescent but not completely rigid
  • Often trauma-related

Treatment Algorithm for Ischemic Priapism

First-Line Treatment:

1. Corporal aspiration with or without irrigation (30% resolution rate)

   • Use 19-21 gauge butterfly needle inserted into lateral aspect of proximal penis
   • Aspirate old, dark blood
   • May irrigate with normal saline 1

2. Intracavernous injection of phenylephrine (43-81% resolution rate)

   • Preferred sympathomimetic due to lower cardiovascular side effects
   • Dosing: 100-500 μg diluted in saline
   • Maximum dose: 1 mg in one hour
   • Monitor blood pressure and heart rate during administration 1

Second-Line Treatment (if priapism persists):

• For priapism <24 hours: Repeat phenylephrine injection
• For priapism 24-48 hours: Surgical shunting procedures
  • Distal shunts first (66-74% resolution rate)
  • Proximal shunts if distal fails (76-77% resolution rate) 1, 2
• For priapism >48 hours: Consider immediate penile prosthesis implantation 2

Special Considerations

Sickle Cell Disease and Hematologic Disorders

• Intracavernous treatment should not be delayed for disease-specific interventions
• Systemic treatments alone have poor resolution rates (0-37%)
• Provide concurrent systemic treatment for the underlying disease while treating the priapism directly 3, 1

Renal Failure

• Use lower doses of phenylephrine (50-100 μg)
• Reduce maximum total dose to 500 μg in an hour
• Monitor cardiovascular parameters closely 1

Time Sensitivity and Outcomes

• Treatment efficacy decreases significantly after 48 hours
• Significant risk of erectile dysfunction after 18 hours
• Permanent erectile dysfunction likely after 36 hours 1

Management of Non-Ischemic Priapism

• Often resolves spontaneously (up to 62% of cases)
• Conservative measures: ice and site-specific compression
• If persistent >6 months or patient requests treatment: selective arterial embolization (74-78% resolution rate) 1, 2

Prevention of Stuttering Priapism

• PDE5 inhibitors may be effective for prevention
• Self-injection of sympathomimetics at home for early intervention 1, 2

Common Pitfalls to Avoid

1. Delaying treatment: Ischemic priapism is a urological emergency requiring immediate intervention
2. Misdiagnosis: Failure to differentiate between ischemic and non-ischemic priapism leads to inappropriate treatment
3. Inadequate monitoring: Cardiovascular monitoring is essential during sympathomimetic administration
4. Relying solely on systemic treatments in patients with underlying disorders like sickle cell disease 3, 1
5. Using standard doses in renal failure patients: Dose modification is critical 1

Remember that time is critical in ischemic priapism management, with each hour of delay increasing the risk of permanent erectile dysfunction.