Overview
Priapism
Topic Overview
Summary
Priapism is a persistent erection lasting over 4 hours, unrelated to sexual stimulation. There are two main types: ischaemic (low-flow, painful, emergency) and non-ischaemic (high-flow, painless, non-urgent). Ischaemic priapism is a urological emergency — delay leads to permanent erectile dysfunction. Causes include sickle cell disease, intracavernosal injections, and drugs (antipsychotics, cocaine). Treatment of ischaemic priapism is aspiration and phenylephrine injection. Surgical shunt is required if medical treatment fails.
Key Facts
- Definition: Erection over 4 hours unrelated to sexual arousal
- Ischaemic (low-flow): Painful, rigid, emergency — irreversible damage after 4-6 hours
- Non-ischaemic (high-flow): Painless, partially erect, non-urgent (arterial fistula)
- Common causes: Sickle cell, intracavernosal injections, drugs
- Treatment (ischaemic): Aspiration + phenylephrine injection ± surgical shunt
- Outcome: Erectile dysfunction if delayed treatment
Clinical Pearls
Ischaemic priapism = compartment syndrome of the penis — treat within 4-6 hours
Sickle cell is the commonest cause in children and adolescents
Blood gas from aspirate: Dark blood + acidosis = ischaemic; bright red = non-ischaemic
Why This Matters Clinically
Ischaemic priapism causes irreversible erectile dysfunction if not treated within hours. All emergency physicians must recognise this and initiate treatment promptly.
Visual Summary
Visual assets to be added:
- Priapism management algorithm
- Intracavernosal injection technique diagram
- Blood gas interpretation table
- Ischaemic vs non-ischaemic comparison
Epidemiology
Incidence
- 1.5 per 100,000 men/year
- Higher in sickle cell disease (up to 40% lifetime)
Demographics
- Bimodal: Children (sickle cell) and adults (drugs, injections)
- Peak: 5-10 years (sickle cell) and 20-50 years (drugs)
Causes
| Category | Examples |
|---|---|
| Haematological | Sickle cell disease (most common in children), thalassaemia, leukaemia |
| Drugs | Intracavernosal injections (PGE1), antipsychotics, trazodone, cocaine, sildenafil |
| Trauma | Perineal/penile trauma (non-ischaemic) |
| Neurological | Spinal cord injury |
| Idiopathic | Up to 30% |
Pathophysiology
Ischaemic (Low-Flow) Priapism
- Venous outflow obstruction
- Blood stasis in corpora cavernosa
- Progressive hypoxia and acidosis
- Smooth muscle necrosis
- Fibrosis → permanent erectile dysfunction
Non-Ischaemic (High-Flow) Priapism
- Arterial-lacunar fistula (usually after trauma)
- Unregulated arterial inflow
- No venous obstruction
- Oxygenated blood — no ischaemia
- Not a true emergency
Time to Irreversible Damage (Ischaemic)
- Over 4-6 hours: Smooth muscle damage begins
- Over 12 hours: Significant necrosis
- Over 24-48 hours: Near-complete erectile dysfunction
Sickle Cell Mechanism
- Sickling in corpora cavernosa
- Venous outflow obstruction
- Recurrent stuttering priapism common
Clinical Presentation
Ischaemic (Low-Flow)
| Feature | Description |
|---|---|
| Duration | Over 4 hours |
| Pain | Yes (often severe) |
| Rigidity | Fully rigid corpora cavernosa |
| Glans | Soft (spared) |
| Aspirate | Dark, acidotic blood |
Non-Ischaemic (High-Flow)
| Feature | Description |
|---|---|
| Duration | Variable |
| Pain | Minimal or none |
| Rigidity | Partial (less rigid) |
| History | Often trauma |
| Aspirate | Bright red, oxygenated blood |
Red Flags
| Finding | Significance |
|---|---|
| Duration over 4 hours | Ischaemic damage risk |
| Severe pain | Ischaemic |
| Fully rigid + soft glans | Classic ischaemic |
| Known sickle cell | High risk |
Clinical Examination
Penile Examination
- Rigidity of corpora cavernosa
- Glans soft (ischaemic) or partially tumescent (non-ischaemic)
- Tenderness (ischaemic)
Perineal Examination
- Signs of trauma (non-ischaemic)
General
- Signs of sickle cell crisis
- Drug use history
Investigations
Cavernosal Blood Gas — Key Investigation
| Parameter | Ischaemic | Non-Ischaemic |
|---|---|---|
| pO2 | Under 30 mmHg | Over 90 mmHg |
| pCO2 | Over 60 mmHg | Under 40 mmHg |
| pH | Under 7.25 | Over 7.35 |
| Colour | Dark | Bright red |
Other Investigations
- FBC, reticulocyte count (sickle cell)
- Sickle cell screen (if unknown status)
- Toxicology (if drug use suspected)
- Penile Doppler USS (non-ischaemic — shows fistula)
Classification & Staging
By Type
| Type | Mechanism | Urgency |
|---|---|---|
| Ischaemic (low-flow) | Venous outflow obstruction | Emergency |
| Non-ischaemic (high-flow) | Arterial fistula | Non-urgent |
| Stuttering | Recurrent short episodes; progresses to ischaemic | Variable |
Management
Ischaemic Priapism — Emergency
1. Analgesia:
- Paracetamol, opioids if needed
- Penile block (dorsal nerve block)
2. Aspiration:
- 19G butterfly into corpus cavernosum (lateral aspect, avoid urethra/dorsal neurovascular bundle)
- Aspirate dark blood until bright red returns
3. Phenylephrine Injection:
- Dilute phenylephrine (100-500 mcg/mL)
- Inject 0.5-1 mL into corpus cavernosum
- Repeat every 3-5 minutes (up to 1 hour)
- Monitor BP and pulse (alpha-agonist)
4. Surgical Shunt (If Medical Fails):
- Distal shunt first (Winter, Al-Ghorab)
- Proximal shunt if distal fails
- Penile prosthesis if refractory
Non-Ischaemic Priapism
- Not urgent
- Observation (may resolve spontaneously)
- Selective arterial embolisation (if persistent)
Sickle Cell-Related Priapism
- IV fluids, oxygen
- Analgesia
- Exchange transfusion (if severe or refractory)
- Aspiration and phenylephrine as above
Prevention of Recurrence (Stuttering)
- Oral alpha-agonists (pseudoephedrine)
- Hormonal therapy (in selected cases)
- Referral to haematology (sickle cell)
Complications
Of Ischaemic Priapism
- Permanent erectile dysfunction (up to 90% if over 24 hours)
- Penile fibrosis
- Penile shortening
- Psychological impact
Of Treatment
- Bruising, haematoma
- Infection
- Phenylephrine side effects (hypertension, bradycardia)
- Shunt complications
Prognosis & Outcomes
Erectile Function After Ischaemic Priapism
| Duration | ED Rate |
|---|---|
| Under 12 hours | Under 10% |
| 12-24 hours | 50% |
| Over 24 hours | Over 90% |
Non-Ischaemic
- Excellent prognosis
- Low risk of ED
Evidence & Guidelines
Key Guidelines
- EAU Guidelines on Priapism
- AUA Guidelines on Priapism
Key Evidence
- Aspiration and phenylephrine are first-line for ischaemic priapism
- Early treatment preserves erectile function
Patient & Family Information
What is Priapism?
Priapism is a prolonged erection that lasts more than 4 hours and is not caused by sexual arousal. It is a medical emergency and needs urgent treatment.
Why is it Urgent?
Without treatment, the blood supply to the penis is affected, which can cause permanent damage to your erections.
Treatment
- Draining blood from the penis with a needle
- Injection of medication to reduce the erection
- Surgery if other treatments don't work
Causes
- Sickle cell disease
- Medications
- Recreational drugs
Resources
References
Primary Guidelines
- Salonia A, et al. EAU Guidelines on Priapism. Eur Urol. 2022. uroweb.org
Key Studies
- Broderick GA, et al. Priapism: pathogenesis, epidemiology, and management. J Sex Med. 2010;7(1 Pt 2):476-500. PMID: 20092449
- Burnett AL, Bivalacqua TJ. Priapism: current principles and practice. Urol Clin North Am. 2007;34(4):631-642. PMID: 17983901