Nonischaemic Priapism

Nonischaemic priapism (high flow, arterial priapism) is a persistent, usually painless, partial erection caused by unregulated arterial inflow into the corpora cavernosa.

• Cause: a fistula between the cavernosal artery and cavernosal sinusoids, usually after blunt perineal or penile trauma (straddle injury), kick or fall, or iatrogenic injury (needle biopsy, intracavernosal injection, penile surgery); also in sickle cell disease, after shunt surgery and rarely spontaneously.
• It is not a medical emergency, since cavernosal tissue stays well oxygenated, and it accounts for under 10 percent of priapism.
• Onset may be delayed 24 hours to weeks after the injury.

Erection that is partly rigid (not fully rigid), painless or mildly uncomfortable, not related to sexual stimulation, and increases with arousal; the glans and spongiosum are not rigid.

• History of recent trauma to the perineum or penis; possible perineal haematoma; erection may subside and return.
• Differential diagnosis: ischaemic priapism, normal erection, penile fracture, penile tumour, Peyronie disease, spinal cord lesion, drug-induced erection.
• Complications: erectile dysfunction (5 to 20 percent, mainly after treatment or long duration), psychological distress, rarely corporal fibrosis with prolonged high flow state and pseudoaneurysm rupture.

Cavernosal blood gas (if needed to distinguish): bright red, oxygenated blood with pO2 above 90 mmHg, pCO2 below 40 mmHg, pH about 7.4.

• Colour Doppler ultrasound of the penis and perineum: normal or high velocity turbulent flow in the cavernosal artery with a fistula or pseudoaneurysm (arterial-lacunar fistula) is diagnostic.
• Selective internal pudendal arteriography confirms the fistula and is done at the time of embolisation.
• Full blood count and sickle cell test.

Supportive

• Reassurance and watchful waiting (many resolve spontaneously, about 60 percent, over weeks to months); ice and perineal compression may help in the early phase; avoid aspiration and shunting of the cavernosa (unnecessary and harmful).
• Patients should accept the risk and may remain sexually active with the partially rigid erection, though sexual function may need support.

Pharmacological

• No drug reliably stops high flow priapism; alpha-agonist injections such as phenylephrine are ineffective and should not be used.
• Analgesia as needed (paracetamol 1 g every 6 hours).
• Androgen suppression (cyproterone acetate 100 mg daily or leuprolide) has been used for refractory cases.

Procedures

• Selective arterial embolisation, indicated when the patient requests resolution or the priapism persists, with absorbable material (autologous blood clot, gelatin sponge); resolution is 70 to 90 percent; recurrence in about 25 percent; erectile dysfunction in about 5 percent; permanent materials (coils, glue) cause more erectile dysfunction and are avoided.
• Surgical ligation of the fistula for failed embolisation (rarely).
• Repeat embolisation if recurrence.

Special groups: children (watchful waiting, embolisation if persistent), sickle cell disease (exclude ischaemic type first).

Red flags: increasing pain, full rigidity (switch to ischaemic priapism pathway), inability to void, infection.

Follow-up: review every 1 to 2 weeks; Doppler at 4 to 6 weeks; assess erectile function at 3 and 6 months.