Priapism is a persistent erection (>4 hours) unrelated to stimulation. The critical first step is distinguishing ischemic (low-flow, painful — a compartment-syndrome emergency) from non-ischemic (high-flow, traumatic, not an emergency); corporal blood gas settles indeterminate cases. Ischemic priapism risks permanent erectile dysfunction, and the chance of recovery falls steeply with duration.
Classification
| Feature | Ischemic (low-flow, veno-occlusive) | Non-ischemic (high-flow, arterial) |
|---|---|---|
| Frequency | Most common | Rare |
| Pain | Painful, rigid, tender corpora | Painless, tumescent but not fully rigid |
| Cavernous blood gas | Hypoxic, hypercarbic, acidotic (dark) | Normal (bright red) |
| Cause | Non-traumatic (drugs, SCD, malignancy) | Traumatic — cavernous-artery laceration (straddle injury) |
| Urgency | Emergency | Not emergent |
Recurrent ("stuttering") ischemic priapism is repeated ischemic episodes (± the 4-hour criterion), strongly associated with sickle cell disease — the commonest cause of priapism in children. Recovery of erectile function after an ischemic episode depends on time to reversal: ~100% if <12 h, ~75% at 12–24 h, ~50% at 24–36 h, and 0% beyond 36 h (erectile tissue is likely irreversible by ~48 h).
Risk Factors
Medications (α-blockers, trazodone and antipsychotics, anticoagulants, antihypertensives, ADHD stimulants, hormones, intracavernosal vasoactive agents), recreational drugs (cocaine, alcohol, marijuana), genitourinary trauma, thrombophilia, and haematologic disease — above all sickle cell disease (priapism in 23–89% of males by age 18). Other causes include malignant infiltration (prostate, bladder, urethra), neurogenic causes (spinal-cord injury), and metabolic disease (Fabry, amyloidosis).
Diagnosis
History and examination usually distinguish the subtypes (the corpora cavernosa are affected; the glans and spongiosum are spared). Corporal blood gas is the key test when in doubt:
| Source | PO₂ | PCO₂ | pH |
|---|---|---|---|
| Normal arterial | >90 | <40 | 7.40 |
| Normal venous | 40 | 50 | 7.35 |
| Ischemic priapism | <30 | >60 | <7.25 |
CBC, haemoglobin electrophoresis, and toxicology are selective. Penile colour-Doppler ultrasound differentiates indeterminate cases (ischemic — absent cavernosal flow; non-ischemic — high systolic velocities or a fistula) but is not part of the first-line ED workup.
Ischemic Priapism — Management
An emergency — counsel about the risk of ED and penile shortening. Conservative measures (observation, oral agents, cold packs) are not recommended, and cold compresses are contraindicated in SCD.
- First-line: intracavernosal phenylephrine + corporal aspiration ± saline irrigation. Phenylephrine (α1-selective, fewest systemic effects) is diluted to 100–500 mcg/mL and injected laterally (3/9 o'clock), doses ≥5 min apart for up to 1 hour; aspirate before injecting. Monitor BP and heart rate (adverse effects: hypertension, reflex bradycardia, headache); a cumulative dose of ~2 mg has caused hypertensive stroke.
- Surgical shunting if refractory after phenylephrine + aspiration/irrigation (consider for episodes ≤72 h; generally forego beyond 72 h). A distal corporoglanular shunt ± tunnelling is first choice (percutaneous Winter, Ebbehoj, T-shunt; open Al-Ghorab); proximal shunts (Quackles, Grayhack, Barry) are largely historical. Shunt complications: oedema, haematoma, infection, urethral fistula, penile necrosis, PE.
- >36 hours or refractory: options are observation, distal shunting, or early penile prosthesis (within 2 weeks) — giving detumescence, pain relief, and preserved length, with infection <10% (higher if delayed).
Recurrent (Stuttering) Priapism
Abort acute episodes (phenylephrine + aspiration), then prevent recurrence. Pharmacologic prophylaxis (usually at bedtime): ketoconazole + prednisone (highest success — monitor LFTs), pseudoephedrine, PDE5 inhibitors, dutasteride, baclofen, and anti-androgens/GnRH agents (which impair fertility and sexual function). In SCD, add hydroxyurea and chronic exchange transfusion; home self-injection of an α-agonist can avert a developing episode.
Non-Ischemic Priapism
Not an emergency, and aspiration is only diagnostic. First-line is observation (resolves spontaneously in up to 62%; reasonable for ~4 weeks), with penile Doppler to locate the fistula. Second-line is percutaneous arterial embolization (detumescence ~85%, ~80% retain erectile function; recurrence ~30%, so repeat if it fails — bilateral embolization raises ED risk). Surgical fistula ligation (transcorporal) is reserved for embolization failure.
Self-Test
1. Define priapism and its subtypes. A full or partial erection lasting >4 hours beyond or unrelated to stimulation; the subtypes are ischemic, non-ischemic, and recurrent (stuttering) ischemic.
2. Recovery of erectile function by time to reversal (12 h / 12–24 h / 24–36 h / >36 h)? ~100% / ~75–80% / ~45–50% / 0%.
3. Beyond what duration is shunting generally not recommended? 72 hours.
4. Corporal blood-gas values in ischemic priapism? PO₂ <30, PCO₂ >60, pH <7.25 (versus normal arterial >90 / <40 / 7.40).
5. Maximum phenylephrine dose and its adverse effects? ~2 mg cumulative; hypertension, reflex bradycardia, tachycardia, arrhythmias, headache, and dizziness.
6. Name the distal and proximal shunts. Distal — Winter, Ebbehoj, T-shunt (percutaneous), Al-Ghorab ± corporal tunnelling (open); proximal — Quackles (cavernosum-spongiosum), Grayhack (saphenous), Barry (deep dorsal vein).
7. What prophylaxis is used for stuttering priapism? Ketoconazole + prednisone (first-line), pseudoephedrine, PDE5 inhibitors, anti-androgens/GnRH agents, and — in SCD — hydroxyurea or exchange transfusion.