Summary

Priapism is a persistent erection lasting >4 hours, occurring without sexual stimulation. It is a urological emergency. It is classified into two types: Ischaemic (Low-flow) and Non-Ischaemic (High-flow). Ischaemic priapism accounts for >95% of cases and represents a compartment syndrome of the penis; if left untreated, cavernous tissue necrosis leads to permanent erectile dysfunction (ED). [1,2]

Clinical Pearls

The "Soft Glans" Sign: In Ischaemic Priapism, the Corpora Cavernosa (erectile bodies) are rigidly ischaemic, but the Corpus Spongiosum (which houses the urethra and forms the glans) is usually flaccid because its venous drainage is separate. If the glans is soft but the shaft is rock hard -> Think Ischaemic.

Sickle Cell Disease: The most common cause in children. Sickled red cells sludge in the sinusoids. Unlike other causes, hydration/oxygen/exchange transfusion are first line therapies before aspiration in these patients to reverse the sickling.

Cavernosal Blood Gas: The definitive test. You must insert a needle directly into the penis to aspirate blood.

• Black/Dark Blood (pH < 7.25) = Ischaemic (Emergency).
• Red/Bright Blood (pH > 7.40) = Non-ischaemic (Observe).

Management Algorithm

         ERECTION > 4 HOURS (PAINFUL)
                    ↓
        ANALGESIA + DORSAL PENILE BLOCK
          (Local anaesthetic ring block)
                    ↓
             ASPIRATION (16G/18G)
     (Needle into Corpus Cavernosum at 3 or 9 o'clock)
     (Aspirate 10-20ml old blood -> Send Gas)
                    ↓
             ISCHAEMIC CONFIRMED?
                    ↓
          IRRIGATION (Washout)
     (Inject cold saline, aspirate, repeat)
                    ↓
           INTRACAVERNOSAL AGENT
     (Phenylephrine 200mcg aliquots every 5 mins)
     (Monitor BP/HR for hypertension)
                    ↓
              SUCCESS?
        ┌─────────┴─────────┐
       YES                  NO
        ↓                   ↓
    OBSERVE             SURGERY
   (For 24h)           (Shunt)

1. First Aid

• Ice packs.
• Exercise (stairs) - tries to shunt blood to legs (rarely works).
• Ejaculation (rarely works).

2. Aspiration & Irrigation

• Use a large bore needle (butterfly 19G or 16G/18G).
• Insert laterally (avoiding urethra).
• Aspirate dark blood until bright red blood flows. Usually provides immediate pain relief.

3. Intracavernosal Vasoconstrictors

• Phenylephrine: Pure Alpha-1 agonist. Safer cardiovascular profile than Adrenaline.
• Dilute to 100-200mcg/ml. Inject 1ml every 3-5 mins. Max dose 1mg.
• Contraindications: Careful in MAOI users / Severe CVD.

4. Surgical Shunts

• Distal (Winter's / Ebbehoj): Fistula created between glans and cavernosa using a needle or scalpel.
• Proximal: If distal fails.

• Observation: Most close spontaneously.
• Embolisation: If persistent, radiological embolisation of the fistula.
• Surgery: Ligature (rarely needed).

• less than 12 hours: Good recovery likely.
• >24 hours: Permanent structural damage almost certain. Penile prosthesis may be required later.

Key Guidelines

Landmark Data

1. Phenylephrine Safety

• Studies confirm Phenylephrine causes less tachycardia/arrhythmias than Adrenaline or Ephedrine when injected intracavernosally, making it the standard of care.

What is Priapism?

It is a prolonged erection that won't go away and isn't linked to sexual feelings. It is often very painful.

Why is it an emergency?

The blood trapped in the penis loses its oxygen, causing the tissue to suffocate. If this lasts too long (more than 4-6 hours), the tissue dies and turns into scar tissue, meaning you may never get a natural erection again.

What causes it?

Often it is a side effect of medicines (especially those for erection problems or mental health) or recreational drugs. In children, it is often due to Sickle Cell disease.

What is the treatment?

We numb the penis, then put a needle into the side to drain the "stuck" blood. We may wash it out with salty water and inject a medicine to make the blood vessels squeeze shut.

Common Exam Questions

1. Diagnosis: "Differentiation test?"
   • Answer: Cavernosal Blood Gas.
2. Pharmacology: "Drug causing priapism?"
   • Answer: Trazodone (Antidepressant) or Sildenafil.
3. Treatment: "First line agent?"
   • Answer: Phenylephrine.
4. Paediatrics: "Commonest cause in child?"
   • Answer: Sickle Cell Disease.

Viva Points

• Adrenaline vs Phenylephrine: Phenylephrine is pure Alpha-1. Adrenaline has Beta effects which cause tachycardia/arrhythmias when they enter systemic circulation. Hence Phenylephrine is safer.
• Trazodone: An old antidepressant often used for insomnia. Priapism is a rare (1 in 10,000) but famous side effect due to Alpha-blocking activity.

Medical Disclaimer: MedVellum content is for educational purposes and clinical reference. Clinical decisions should account for individual patient circumstances. Always consult appropriate specialists.