Priapism

Priapism is defined as a long-standing and painful erection that lasts longer than four hours without sexual stimulation and is unrelieved by ejaculation.

The word “Priapism” has its roots in Greek mythology. The term is named after a Greek god of fertility called Priapus, who is said to be a son of Zeus. A jealous female cast a spell over Priapus’ mother whilst she was pregnant, causing her son Priapus to be born with this affliction for which he was disowned by his mother. Priapus is often represented in ancient statues and paintings with a disproportionately large and permanent erection.

In reality, priapism is a very serious condition and is considered to be a medical emergency that requires immediate treatment. An erection that lasts too long can cause permanent damage to the penis, with the risk of impotence being as high as 50% in males affected by priapism.

Priapism and leukaemia

Priapism in its own right is a very rare disease, and so for priapism to be caused by leukaemia is extremely uncommon. About two thirds of adult cases of priapism are caused by the use of agents to treat erectile dysfunction and, in children, the major cause of priapism (67%) is sickle cell anaemia. Generally speaking, leukaemia is only responsible for around 20% of all the cases of priapism, and the incidence in adult leukaemic patients is as little as 1-5%.  Approximately half of these have chronic myeloid leukaemia (CML) as it is far more common to have priapism with chronic leukaemia than acute leukaemia.

There are three different types of priapism, all of which vary in the underlying biological cause:

Low-flow priapism (ischemic)

Low-flow priapism occurs when blood becomes trapped in the erection chambers, meaning it is not able to leave the penis after an erection. This is the most common type of priapism and represents over 95% of cases.

Symptoms of low-flow priapism include:

• Erection lasting over four hours or at times unconnected to sexual interest or stimulation.
• Pain in penis that gets progressively worse.
• Rigid penile shaft, but the tip of the penis (glans) remains soft.

It is low-flow priapism that can present in men affected by leukaemia (as well as sickle-cell disease and malaria).

How does leukaemia cause low-flow priapism?

Priapism in leukaemia is caused by an abnormally high number of white blood cells in the blood, which can occasionally cause the blood to thicken and clog up the small veins, leading to decreased blood flow out of the penis and stagnation of the blood. When blood becomes stagnant, it cannot replenish oxygen, which means that the penile tissue becomes deprived of oxygen, often leading to long term damage.

Another contributing factor to the congestion of blood flow out of the penis is the result of physical pressure upon the abdominal veins by an enlarged spleen (splenomegaly), a comparatively common symptom of leukaemia.

Stuttering priapism

Stuttering priapism is a more uncommon type of low-flow (ischemic) priapism. It is a recurring form of low-flow priapism which is identified by episodes of unwanted and/or painful erections that last for three hours or more. It occurs repeatedly with intervening periods where the penis relaxes and subsides from its swollen state. This type of priapism is more likely in males who have inherited a genetic disorder which changes the shape of their red blood cells (e.g. sickle cell anaemia) as these abnormally shaped cells can temporarily block the blood vessels.

High-flow priapism (non-ischemic)

This type of priapism is rarer than low-flow and is usually not as painful. The cause of this type of priapism is usually from an injury to the penis or the perineum (the area between the scrotum and anus). This then prevents the blood in the penis from circulating normally.

Symptoms of high-flow priapism:

• Erection lasting over four hours or at times unconnected to sexual interest or stimulation.
• Erect but not fully rigid penile shaft
• Often painless

How is priapism treated?

Treatment of priapism depends on the type and the cause. Your doctor will evaluate your symptoms and run tests to decide whether it is ischemic or non-ischemic, as well as the possible cause.

If the erection has lasted for four to six hours, decongestive medication in tablet form is usually effective as an immediate relief method.

However, if this doesn’t work, other treatments to help reduce your erection might be:

• Decongestive medications injected directly into your penis
• Aspiration – where the penis is numbed with local anaesthetic, using a needle to drain the excess blood.
• Surgery whilst you are asleep under general anaesthetic to draw out the blood through a small incision.

Due to the relative rarity of priapism occurring as a symptom of leukaemia, there are currently no standard protocols for its treatment or management in leukaemia patients, and there is still debate over what method is most effective. However, all methods look to reduce the excess burden of white blood cells in the blood causing the blockage (hyperleukocytosis).

A rather out-dated technique used in the past included local radiotherapy, with or without open surgical shunting (using a long needle to create a bypass around the obstructed portion of the vein in the penis).

More recent therapies include:

• Chemotherapy to kill the excess white blood cells clogging the veins of the penis
• Leukapheresis to temporarily reduce the number of leukaemia cells in the blood.
• In the case of CML, initiation of TKI therapy with agents such as imatinib to selectively kill the cancer cells.

Need support?

Contact a member of our support team by calling our free helpline on 08088 010 444, via WhatsApp message at 07500 068 065 or by emailing our team at support@leukaemiacare.org.uk (services available Monday to Friday, 9am – 5pm).