Tests For Erection Problems: Test Overview

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Test Overview

Tests for erection problems can help find a cause for a man's problem in having or maintaining an erection (erectile dysfunction, or impotence). Erectile dysfunction is a common male problem. Most erection problems are caused by a combination of blood vessel, nerve, or psychological issues.

To find the cause of erection problems, your doctor will first ask about your sexual history and do a physical exam. During the physical exam, the doctor will:

• Check your blood pressure.
• Check your penis and testicles for any problems.
• Order blood tests to check testosterone, luteinizing hormone (LH), prolactin, and thyroid hormone levels.

Other tests that may be done as part of a physical exam include:

• Blood tests, such as a complete blood count (CBC), blood glucose, cholesterol, and triglyceride.
• A urine test.

If the results of your physical exam and other tests are normal, your doctor may have you try a medicine, such as sildenafil citrate (Viagra), tadalafil (Cialis), or vardenafil (Levitra), before doing more tests.

This topic focuses on three more tests you may have after the physical exam and lab tests listed above. These three specific tests used to find the cause of erection problems are:

• Nocturnal penile tumescence (NPT) test.
• Intracavernosal injection test.
• Doppler ultrasound.

Nocturnal penile tumescence (NPT) test

The NPT test checks whether a man is having normal erections during sleep. Most men have 3 to 5 full erections during deep (rapid eye movement, or REM) sleep. Men who do not have erections because of psychological problems can still have erections during deep sleep. Occasionally, some sleep problems or serious depression can prevent these normal nighttime (nocturnal) erections.

This test can be done at home or in a special sleep lab. One of two ways may be used.

• A simple ringlike device called a snap gauge made up of plastic films is fitted around the penis. The films break at certain pressures. So an erection during sleep will cause the film to snap.
• An electronic monitoring device is more expensive than using the snap gauge, but it is more accurate and gives more detailed information about erections during sleep. This device records how many, how long, and how rigid the erections are during sleep.

Tests are usually done for at least two nights in a row. If good erections occur during sleep, the cause of the erection problems probably is not physical.

The NPT test may also be called the stamp test or the rigidity test.

Intracavernosal injection test

During this test, the doctor injects a medicine (usually prostaglandin E1) into the base of the penis to make an erection. This is called an intracavernosal injection. A similar medicine may also be placed into the urethra, the tube through which urine leaves the penis. This is called an intraurethral injection. The fullness of the erection and how long the erection lasts are measured.

Doppler ultrasound test

Doppler ultrasound (also called color duplex Doppler) uses a handheld tool passed lightly over the penis. The tool uses reflected sound waves to estimate the speed and direction of blood as it flows through a blood vessel. The sound waves go to a computer that changes the sounds to colors that are overlaid on a picture of the blood vessel. This shows the speed and direction of blood flow.

Your tests for erection problems may show that medical treatment is a choice for you. For more information, see:

Should I use injections for erection problems?

Should I use phosphodiesterase-5 inhibitors for erection problems?

Last updated:	May 21, 2008
Author:	Monica Rhodes
Reviewed By:	E. Gregory Thompson, MD - Internal Medicine, Christopher G. Wood, MD, FACS - Urology/Oncology
Editors:	Kathleen M. Ariss, MS, Tracy Landauer