Tests and diagnosis

By Mayo Clinic Staff

If you have an erection lasting more than four hours, you need emergency care. The emergency room doctor will determine first whether you have ischemic priapism or nonischemic priapism. This is necessary because the treatment for each is different, and treatment for ischemic priapism needs to be done as soon as possible.

Medical history and exam

To determine what type of priapism you have, your doctor will likely ask numerous questions and examine your genitals, abdomen, groin and perineum. He or she may be able to determine what type of priapism you have based on the rigidity and sensitivity of the penis. This exam may also reveal signs of injury or tumors that could be causing priapism. An injury, for example, would suggest that nonischemic priapism is more likely.

Diagnostic tests

Diagnostic tests may be necessary to determine what type of priapism you have. Additional tests may identify the cause of priapism. In an emergency room setting, your treatment may begin before all test results are received if the doctor is confident about what kind of priapism you have. Diagnostic tests include:

  • Blood gas measurement. In this test, a tiny needle is inserted into your penis to remove a sample of blood. If the blood is dark — deprived of oxygen — the condition is most likely ischemic priapism. If it's bright red, the priapism is most likely nonischemic. A laboratory test measuring the amounts of certain gases in the blood can confirm the type of priapism.
  • Blood tests. Your blood can be tested to measure the number of red blood cells and platelets present. Results may provide evidence of diseases, such as sickle cell anemia, other blood disorders or certain cancers.
  • Ultrasound. You may have color duplex ultrasonography, which uses sound waves to create an image of internal organs. This test can be used to measure blood flow within your penis that would suggest ischemic or nonischemic priapism. The exam may also reveal an injury, tumor or abnormality that may be an underlying cause.
  • Toxicology test. Your doctor may order a test to screen for illegal or prescription drugs that may be the cause of priapism. This test may be done with blood or urine samples.
June 15, 2013