Priapism

Priapism is a persistent penile erection that continues for hours beyond sexual stimulation or occurs without sexual stimulation.

For clinical purposes, priapism is generally defined as an erection lasting more than four hours.

Priapism is not simply an unusually long normal erection. It results from abnormal regulation of penile blood flow and can occur even without sexual desire or stimulation.

The most important step is determining whether the patient has ischemic priapism or non-ischemic priapism, because their urgency, underlying mechanisms, and treatments are different.

Why can priapism be dangerous?

During ischemic priapism, blood becomes trapped inside the corpora cavernosa and cannot adequately leave the penis.

As the episode continues, oxygen levels inside the erectile tissue fall while carbon dioxide and acidity increase.

Prolonged ischemia can injure the smooth muscle responsible for normal erections. The longer ischemic priapism remains untreated, the greater the risk of tissue necrosis, corporal fibrosis, penile shortening, and permanent erectile dysfunction.

For this reason, a persistent erection approaching or exceeding four hours requires urgent medical assessment rather than waiting for it to resolve at home.

Priapism and erectile dysfunction

Priapism can paradoxically lead to erectile dysfunction.

This is particularly important after prolonged ischemic priapism. Damage to the smooth muscle of the corpora cavernosa may subsequently make normal erections difficult or impossible.

The risk increases as the duration of ischemia increases.

Men presenting after very prolonged episodes may require surgical intervention, and in severe cases where erectile tissue has been irreversibly damaged, penile prosthesis surgery may eventually be considered.

Priapism requires prompt clinical evaluation.

The first goal is to determine whether the erection represents ischemic or non-ischemic priapism because acute ischemic priapism requires emergency treatment.

The doctor will ask about:

• How long the erection has lasted

• Whether it is painful

• Whether the erection followed sexual activity

• Previous episodes of priapism

• Baseline erectile function

• Erectile dysfunction medications or injections

• Prescription medications

• Recreational drugs

• Sickle cell disease or other blood disorders

• Previous penile, pelvic, or perineal trauma

• Neurological conditions

• History of malignancy

A physical examination assesses the penis, genital region, and perineum.

Cavernosal blood gas analysis

Blood can be aspirated directly from the corpus cavernosum when necessary to determine whether the trapped blood is oxygen-depleted.

In ischemic priapism, cavernosal blood is typically dark and demonstrates low oxygen, increased carbon dioxide, and increased acidity.

In non-ischemic priapism, the blood remains well oxygenated and resembles arterial blood.

Penile Doppler ultrasound

Penile duplex Doppler ultrasound may be used when the diagnosis is uncertain or to evaluate suspected high-flow priapism.

It can assess blood flow through the cavernosal arteries and may identify an arterial fistula or pseudoaneurysm following trauma.

Additional tests

Additional testing may be performed to identify the underlying cause and can include:

• Complete blood count

• Testing for sickle cell disease when appropriate

• Other hematologic investigations

• Medication and toxicology assessment when indicated

• Additional imaging in selected cases

Importantly, investigations into the underlying cause should not delay emergency treatment when acute ischemic priapism has been diagnosed.