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
- Intracorporeal 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 ischaernia 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)

Initial intervention may utilize therapeutic aspiration (with or without irrigation) or intracavernous injection of sympathomimetics (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 ananlysis
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.

Penile anatomy - safe areas

Corporeal aspiration has only a diagnostic role. Aspiration with or without injection of sympathomimetic agents is not recommended as treatment.

The initial management of nonischaemic priapism should be observation.
Immediate invasive interventions (embolization or surgery) can be performed at the request of the patient

Priapism Management Flow Diagram

Content by Dr Íomhar O' Sullivan 05/07/2004. Reviewed by Dr ÍOS 26/05/2006. Next review 26/05/2007.