Ischaemic Priapism

Ischaemic priapism (low flow, veno-occlusive priapism) is a persistent, painful, rigid erection lasting more than 4 hours, unrelated to sexual stimulation, with little or no cavernosal blood flow.

• It is a urological emergency: progressive hypoxia, acidosis and smooth muscle necrosis lead to permanent erectile dysfunction if not corrected within 24 to 48 hours (irreversible damage after about 48 hours).
• Causes: sickle cell disease (commonest in children and young men; 30 to 45 percent of affected males), intracavernosal injections (alprostadil, papaverine, phentolamine), phosphodiesterase 5 inhibitors, psychotropic drugs (trazodone, antipsychotics, antidepressants), anticoagulants, cocaine and alcohol, haematological disease (leukaemia, thalassaemia, polycythaemia), neurological disease, spinal cord injury, malignant infiltration, total parenteral nutrition with fat emulsion, and idiopathic.

Fully rigid corpora cavernosa, tender penis, severe pain increasing with time, with a soft glans and spongiosum.

• Patients with sickle cell disease have recurrent episodes ("stuttering" priapism lasting under 4 hours) before a major attack.
• Differential diagnosis: nonischaemic (arterial) priapism, normal sustained erection with sexual stimulation, penile fracture, penile thrombosis, penile tumour or metastasis, Peyronie disease, balanitis.
• Complications: corporal fibrosis, erectile dysfunction (more than 90 percent after 48 hours), penile shortening or deformity, gangrene, infection, psychological harm and recurrence.

History: duration, pain, medications, injections, trauma, sickle cell status, previous episodes.

• Corporal blood gas aspirated from the cavernosa: dark, deoxygenated blood with pO2 below 30 mmHg, pCO2 above 60 mmHg, pH below 7.25.
• Colour Doppler ultrasound: absent or minimal cavernosal arterial flow (can be skipped when treatment is urgent).
• Full blood count and film, sickle cell test, reticulocytes, coagulation, creatinine, toxicology.

Supportive: urgent assessment, analgesia (morphine 2.5 to 5 mg IV, or penile block with 1 percent lidocaine at the base of the penis, 5 to 10 mL), oxygen, hydration; avoid ice packs, exercise or intercourse; stop the offending drug.

Pharmacological and procedural (stepwise within hours):

• Step 1: aspirate cavernous blood through a 19 to 21 gauge butterfly needle (20 to 50 mL until bright red blood returns), with saline irrigation; success about 30 percent alone.
• Step 2: intracavernosal phenylephrine 100 to 500 micrograms (diluted to 100 micrograms/mL) every 3 to 5 minutes up to 1 mg in an hour (maximum 1 mg total; use lower doses of 100 micrograms in children and cardiac disease); monitor blood pressure and heart rate; avoid in uncontrolled hypertension or on monoamine oxidase inhibitors; alternative etilefrine or adrenaline 10 to 20 micrograms; success 60 to 80 percent.
• Step 3: surgical shunting when pharmacological therapy fails after 1 hour: distal shunts (percutaneous Winter shunt with a biopsy needle, T-shunt with scalpel, Al-Ghorab excision), then proximal shunts (corporospongiosum or saphenous vein) if distal fail.
• Step 4: early penile prosthesis for priapism lasting beyond 36 to 48 hours with documented non-viable corporal tissue.

Sickle cell disease:

• Aspiration with intracavernosal phenylephrine 100 to 500 micrograms every 3 to 5 minutes, together with hydration (oral and intravenous 1.5 times maintenance), oxygen 2 to 4 L/min, analgesia, and simple or exchange transfusion to lower haemoglobin S below 30 percent if refractory (transfusion alone does not replace local treatment).
• Prevention of stuttering priapism: hydroxyurea 15 to 35 mg/kg/day, tadalafil 5 mg daily, finasteride 5 mg daily, etilefrine 25 to 50 mg at night, pseudoephedrine 60 mg at night; and self-injection of phenylephrine in selected patients.

Special groups: children with sickle cell disease (early parental education: attend within 2 hours of a persisting erection), patients on intracavernosal injections (dose reduction, phenylephrine at home), cardiac disease (careful sympathomimetic use).

Red flags: priapism beyond 4 hours, no response to aspiration and phenylephrine, hypertensive crisis after phenylephrine, bleeding disorder.

Follow-up: review at 1 week, 1 and 3 months; counsel on recurrence and erectile function (offer phosphodiesterase 5 inhibitors after recovery, avoid during sickle crises); penile Doppler to assess function.