Introduction

The term priapism is derived from Priapus, the Greek god of fertility. If left untreated it may lead to irreversible penile ischaemia, necrosis and scarring of the intracavernosal erectile tissue.

Definition and classification

Penile erection that persists beyond, or is unrelated to sexual activity. Typically specialists have tried to define a time beyond which an erection is no longer ‘physiological’ four hours has been accepted in many definitions. It is classified as ischaemic (low flow) or non-ischaemic (high flow).

History

The peak incidence is bi-modal, occurring between 5 to 10 and 20 to 50 years.

Ischaemic priapism: the patient complains of a painful erection (pain may not be present in the first few hours). Fifty per cent of cases are idiopathic. Pharmacological causes include Viagra (sildenafil), the use of intracavernosal therapy (e.g. alprostadil), antipsychotics (e.g. chlorpromazine), antihypertensives (e.g. prazosin), anticoagulants (e.g. intravenous heparin), some antidepressants (e.g. trazodone), and recreational drugs (e.g. cocaine). Haematological diseases such as sickle-cell disease (or trait) and leukaemia are the commonest causes in the young. Rarer aetiologies include cerebrovascular disease, lumbar disk disease, and infiltrating prostate and bladder cancer.

Non-ischaemic priapism is less common and generally not associated with severe pain. Presentation may be delayed by days or months. Typically it is related to trauma to the penis, perineum or pelvis resulting in injury to the cavernosal artery, leading to increased arteriolar inflow of oxygenated blood.

Examination

In ischaemic priapism the patient will have a rigid painful erection, unlike a non-ischaemic priapism in which the penis is typically semierect and non painful. Perineal bruising may be indicative of trauma.