Tests for Erection Problems

Tests for erection problems can help find a cause for a man's problem in having or maintaining an erection (Reference erectile dysfunction Opens New Window, 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 Reference sexual history and do a Reference physical exam Opens New Window. During the physical exam, the doctor will:

• Check your blood pressure.
• Check your penis and testicles for any problems.
• Order blood tests to check Reference testosterone Opens New Window, Reference luteinizing hormone (LH) Opens New Window, Reference follicle-stimulating hormone (FSH) Opens New Window, Reference prolactin Opens New Window, and thyroid hormone levels.

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

• Blood tests, such as a Reference complete blood count (CBC) Opens New Window, blood glucose, Reference cholesterol Opens New Window, and Reference triglyceride Opens New Window.
• 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 (for example, Viagra), tadalafil (for example, Cialis), or vardenafil (for example, 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 records how many, how long, and how rigid the erections are during sleep. 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.

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 alprostadil) into the side of the penis to make an erection. This is called an intracavernosal injection. A similar medicine may also be placed into the Reference urethra Opens New Window, 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. You may need to have medicine injected into your penis (intracavernosal injection) to cause an erection before the Doppler test is done.

The results of your tests may show which kind of treatment is a good choice for you. For more information, see:

Opens New Window Erection Problems: Should I Try Injection Treatments? Opens New Window

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