Priapism
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Direct answer
An erection persisting beyond four hours is priapism, a urological emergency in its common ischaemic (low-flow, veno-occlusive) form: the cavernous smooth muscle fails to relax, trapped blood deoxygenates, and the rigid, painful shaft with a soft glans generates fibrosis and permanent erectile dysfunction if not decompressed within hours. Ischaemic priapism follows intracavernosal injections (papaverine, alprostadil), PDE5 inhibitors, antipsychotics and antidepressants, sickle cell disease, leukaemia and other hyperviscosity states. The rare non-ischaemic (high-flow, arterial) priapism — painless, partially rigid, usually after perineal or penile trauma — creates an arteriocavernosal fistula and is managed expectantly or by superselective embolisation. Diagnosis of the type is by corporal blood gas (dark, hypoxic, acidotic blood in ischaemic priapism) and the treatment ladder for ischaemic priapism runs corporal aspiration with saline irrigation, then intracavernosal phenylephrine injection, with shunt surgery for refractory cases — while sickle cell patients first receive hydration, oxygen and analgesia alongside, never instead of, decompression.
What you must remember
- Two types, two temperaments: ischaemic (low-flow) is painful, fully rigid, an emergency; non-ischaemic (high-flow) is painless, partially tumescent, and rarely damages the penis.
- Blood gas discriminant: ischaemic corporal blood is dark with pH around 7.0-7.25, low oxygen and high CO2; arterial blood resembles normal arterial gas.
- Ischaemic causes: intracavernosal papaverine or alprostadil, PDE5 inhibitors, antipsychotics (phenothiazines, risperidone), antidepressants, sickle cell disease, leukaemia, thalassaemia and other hyperviscosity states.
- High-flow cause: blunt perineal trauma (classic bicycle or saddle injury) creating an arterial-lacunar fistula, confirmed by colour Doppler ultrasound.
- First-line treatment ladder: corporal aspiration (and send blood for gas), saline irrigation, then intracavernosal phenylephrine 100-500 micrograms diluted, repeated with monitoring; sympathomimetic caution in hypertensive and cardiac patients.
- Sickle cell adjuncts: aggressive hydration, oxygen and analgesia — but do not delay urological decompression while waiting for these to work.
- Shunt surgery: distal (Winter, Ebbehoj — glans-cavernosal) then proximal shunts for refractory ischaemic priapism; early intervention (within roughly 24-48 hours) protects erectile function, with delay beyond 72 hours carrying a high chance of permanent dysfunction.
- Recurrent stuttering priapism: in sickle cell disease — managed with etilefrine or pseudoephedrine prophylaxis and haematology input; treat each full episode as an emergency.
A typical exam case
A 28-year-old man with sickle cell trait arrives at 2 a.m. with a painful rigid erection of seven hours after taking sildenafil. The diagnosis of ischaemic priapism is clinical — pain, full rigidity, soft glans — and is confirmed by aspirating dark viscous blood from the corpus cavernosum, which the gas analyser reads at pH 7.12. Treatment proceeds in the same puncture: aspirate 30-60 mL, irrigate with normal saline, then inject diluted phenylephrine 200 micrograms with blood pressure watch, repeating every 5-10 minutes for up to an hour while detumescence is achieved. Simultaneously, intravenous fluids and analgesia address the sickling drive. If the penis re-tumesces despite a full cycle, a Winter shunt (traction of the glans with a biopsy needle creating a glans-cavernosal fistula) is the surgical answer. Had this been a painless partial erection a week after a cycle accident over the crossbar, the pathway flips entirely: Doppler shows arterial fistula, observation is reasonable, and superselective embolisation is the definitive, penis-sparing option.
How the exam frames it
Question writers rely on the painful-versus-painless hinge: any stem with severe pain expects ischaemic management and a time clock; any stem with perineal trauma and a semi-rigid, painless penis expects the arterial diagnosis and Doppler. The second hinge is first drug: phenylephrine, not adrenaline, for intracavernosal use, for its selectivity and safety margin. The sickle cell stem tests whether candidates know adjunctive care accompanies — never replaces — aspiration.
Frequently asked questions
How are ischaemic and non-ischaemic priapism distinguished?
Ischaemic priapism is painful and fully rigid with dark, acidotic corporal blood; non-ischaemic is painless, partially rigid, follows perineal trauma, and Doppler shows arteriocavernosal fistula flow.
What is the first-line treatment of ischaemic priapism?
Corporal aspiration with saline irrigation followed by intracavernosal injection of diluted phenylephrine 100-500 micrograms, repeated under cardiovascular monitoring.
How is priapism in sickle cell disease managed?
Hydration, oxygen and analgesia in parallel, but decompression by aspiration and phenylephrine proceeds without waiting, since the penis tolerates ischaemia poorly.
What is done for refractory ischaemic priapism?
Surgical shunting — distal procedures such as the Winter or Ebbehoj shunt first, proximal shunts if these fail — to re-establish cavernous outflow.
Does non-ischaemic priapism need emergency decompression?
No — it carries a low risk of erectile tissue damage; observation is acceptable, with superselective arterial embolisation for persistent, bothersome cases.