Priapism
Background
- When an erection is abnormally prolonged it is called priapism.
- It is caused by obstruction of the venous drainage of the penis or trauma causing a high-flow state (like a fistula).
- Common causes include:
- Sickle cell disease
- Leukaemia in children
- Intra corporeal injections used to induce erections in patients undergoing treatment for erectile dysfunction
- It can also be drug related (heparin, phenothiazines) or idiopathic
- At presentation there is usually considerable pain due to the ischaemia of the erectile tissue.
- Impotence occurs in up to 50% Priapism is a urological emergency
- Call for help now, bloods for FBC, +/- Hb electrophoresis, +/- drug screen
- Record whether the glans is or is not swollen, examine abdomen and complete rectal examination.
- Try to establish whether this is high flow (non-ischaemic) or low flow
(ischaemic) priapism.
- Low flow = commonest, painful priapism, glans and spongiosum are soft
- High flow = rare, usually trauma related, painless, glans engorged, cavernous blood pH> 7.25, PO2 > 60mmHg
- If sickle cell suspected, involve haematologists first. Treatment involves analgesia, Hydroxyurea, hydration, alkalinisation, and exchange transfusion, the aim being to decrease HbS concentrations by 30% (beware ASPEN syndrome)
In ischaemic - "low flow" - priapism
- Initial intervention may utilize therapeutic aspiration (with or without irrigation) or intracavernous injection of sympathomimetic (Phenylephrine has lowest chance of systemic side effects).
- Cardiac monitoring applied.
- Local or dorsal penile nerve block
- Inject along shaft of penis at 2 and 10 o' clock.
- Aspirate 30 mls of blood each side
- Send blood for gas analysis
- Add 10 mg (usually 1.0 mL) of Phenylephrine to 499 mL of saline 0.9%, yielding a solution with 20 mcg/mL.
- Adult Dose 100-500 mcg per dose, up to 10 doses over an hour; use 10-20 mL of 20 mcg/mL solution by intracavernous injection
- Lower concentrations in smaller volumes should be used in those with severe cardiovascular disease.
In non-ischemic - "high flow" - priapism
Corporeal aspiration has only a diagnostic role. Aspiration with or without injection of sympathomimetic agents is not recommended as treatment.
- The initial management of non ischaemic priapism should be observation.
- Immediate invasive interventions (embolization or surgery) can be performed at the request of the patient.
Management algorithm
Links
US National Guideline Clearing House - Managing Priapism
Priapism - Dr Simon Bell - Clinical Topic Review
