Priapism is a full, rigid erection that lasts for more than 4 hours. It is not necessarily caused by sexual stimulation and it is usually painful.
While priapism isn’t very common, it’s important for men to seek treatment immediately to avoid tissue damage. Left untreated, priapism will lead to erectile dysfunction (ED).
Some common causes of priapism are blood diseases (such as sickle cell anemia), medications (such as antidepressants and erectile dysfunction therapies that are injected into the penis), use of drugs and alcohol, and injury to the penis.
To understand priapism, it helps to review how erections occur.
In normal circumstances, erections are induced by signals from the nervous system – either as a result of sexual stimulation or thoughts or as a reflex during sleep. The signals cause arteries in the penis expand to allow more blood to flow in, causing the erection. Veins constrict to hold the blood in the penis and keep the erection rigid. After the man ejaculates (or if stimulation stops), the extra blood in the penis flows back into the body.
With priapism, there is a problem with this blood flow. Sometimes, too much blood flows into the penis as the erection forms. Or, the blood becomes trapped in the penis, unable to flow back out into the body as expected.
Urologists categorize priapism in two ways.
Ischemic priapism (also called low-flow or venocclusive priapism) happens when blood is trapped in the penis and can’t flow out. This is the most common form of priapism and is marked by a painful, rigid erection that lasts more than four hours. Men with ischemic priapism usually find that the shaft of their penis is hard, but the tip may be soft.
Nonischemic priapism (also called high-flow or arterial priapism) occurs when too much blood flows into the penis, usually because of an injury that disrupts arterial flow. With this type, there usually isn’t much pain, and the penis is less rigid than in ischemic priapism.
Men who have an erection lasting four hours or longer should go to an emergency room or urgent care clinic right away. Nonischemic priapism sometimes resolves on its own, but ischemic priapism needs to be treated as soon as possible. It is critical for a healthcare professional to determine which type of priapism is occurring and treat it accordingly.