Priapism is a prolonged, unwanted, and sometimes painful erection that lasts for more than four hours and is unrelated to sexual stimulation.

During a normal erection, the blood vessels in the penis expand, allowing for increased blood flow. After stimulation is over, the blood exits the penis, causing it to lose its rigidity. With priapism, blood becomes trapped in the penis and is unable to drain. If the engorgement is left untreated, blood vessels in the penis can rupture or the tissue may scar, leading to permanent erectile dysfunction.

Types of Priapism

There are two types of priapism: low flow and high flow.

Low flow priapism: Also called “ischemic," this is the more common type of priapism, making up 80 to 90 percent of all cases. Low flow priapism occurs when veins in the penis constrict and prevent blood from leaving the erection chambers (corpora cavernosa). It can be caused by blood disorders, prescription medication, and substance use. Some men have "stuttering" priapism, which occurs when there are recurrent bouts of low flow priapism interspersed with periods of relief. While low flow priapism may eventually resolve on its own, it will not resolve before the tissue is damaged. This type of priapism requires immediate intervention to avoid irreversible harm to the penis.

High flow priapism: Also known as “nonischemic," high flow priapism is rare and occurs when an artery ruptures, causing an influx of blood to the penis. This is usually due to injury and often resolves spontaneously without causing harm to the penis. In severe cases, where tissue and artery damage occur, surgical repair will be required.

Priapism Causes

Contributing factors include:

  • Blood diseases (such as sickle cell anemia and leukemia)
  • Prescription medications, taken orally or injected, to treat erectile dysfunction (i.e. Viagra, Cialis, Levitra, and others)
  • Antidepressants (such as Prozac and Wellbutrin)
  • Medications to treat psychotic disorders
  • Blood thinners
  • Alcohol abuse and illegal drug use
  • Injury or trauma to the genitals, pelvis, or the perineum
  • Spinal cord injury
  • Blood clots
  • A malignant tumor

Priapism Symptoms

Low flow priapism symptoms include:

  • Unwanted erection lasting more than four hours
  • Unwanted erection off and on for several hours (stuttering priapism)
  • Rigid penile shaft, but a soft penis tip
  • Painful or tender penis

High flow priapism symptoms include:

  • Unwanted erection lasting at least four hours
  • Penis that is erect but not rigid

Diagnosing Priapism

A physical exam of the genitals, abdomen, groin, and perineum is usually the first step to diagnosing the condition and determining which type of priapism is involved based on penile rigidity, sensitivity, and signs of injury or trauma.

Diagnostic tests can include:

  • Blood gas measurement uses a small needle to remove a sample of blood from the penis. The specimen is then sent to a laboratory where it is examined and measured for certain gases. The findings can indicate the type of priapism, how long the condition has been present, and how much damage has taken place.

  • Ultrasound uses sound waves to measure blood flow in the penis and look for an underlying cause, such as tumors, abnormalities, and injury.

  • Toxicology tests to screen for drugs that may be causing an excess of blood flow to the penis. This can be done with blood or urine samples.

Priapism Treatment

If the priapism is ischemic in nature, there are a number of treatment options, including aspiration, medication, and surgery. Since nonischemic priapism often resolves without treatment, doctors typically take a watch-and-wait approach. Learn more about priapism treatment options.


Bassett J, & Rajfer J. (2010). Diagnostic and therapeutic options for the management of ischemic and nonischemic priapism. Reviews in Urology.

Hekel I, & Meuleman E. (2008). Idiopathic low-flow priapism in prepuberty: a case report and a review of literature. Advances in Urology.

Sadeghi-Nejad H, & Seftel AD. (2002). The etiology, diagnosis, and treatment of priapism: review of the American Foundation for Urologic Disease Consensus Panel Report. Current Urology Reports.

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