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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.
Other tests that may be done as part of a physical exam include:
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:
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.
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.
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 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 (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.
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Tests for erection problems are done to help find whether the cause of an erection problem is physical, psychological, or a combination of both.
Physical conditions that may cause erection problems include:
Psychological tests may be needed if no physical cause is found for an erection problem. Psychological causes of erection problems may include:
Do not take any medicines that cause an erection, such as sildenafil (for example, Viagra), tadalafil (for example, Cialis), and vardenafil (for example, Levitra), before the test.
Do not drink alcohol or take sleeping pills for 2 days before you have a nocturnal penile tumescence (NPT) test. The alcohol and the pills can change your deep (REM) sleep time, which can affect nocturnal erections.
If you are having an intracavernosal injection test, tell your doctor if you:
You may be asked to avoid products that contain nicotine (cigarettes, chewing tobacco) for 30 minutes to 2 hours before the test.
It is helpful if you wear briefs-type underwear (not boxer shorts) with a fly front when you are ready for bed. Put your penis through the fly front and keep your pubic hair inside the underwear out of the way. Put the device around your penis. After you put the device on, carefully put your penis inside your underwear.
The types of devices you can use include:
The intracavernosal injection test is generally done by a urologist in the office or clinic. For this test, you will need to take off all of your clothes below the waist, and you will be given a cloth or paper gown to use.
While you sit or stand, your penis will be cleaned with a special soap. Then your doctor will inject a medicine into the side of your penis with a small needle. After the medicine is injected, your doctor may massage the penis for a few seconds to help spread the medicine in the penis. Some doctors may use a band that is gently tightened around the base of the penis for 5 minutes after the medicine is given to make sure an erection occurs.
A low dose of the medicine is used at first. If the low dose does not cause an erection, then a larger dose may be used. An erection should occur within 5 to 10 minutes after the medicine is given.
The medicine may also be given in a thin tablet that is put in the urethra.
After the medicine is given, you may be asked to watch sexually stimulating movies or to massage your penis to cause an erection. Your doctor will measure how rigid and how long the erection lasts. After the test, your doctor may inject a second medicine to make sure your erection goes away.
The Doppler ultrasound test is done by a urologist or ultrasound technician.
You will lie down on an examination table. Your doctor may need to inject a medicine or use a soft band around the penis to cause an erection to see blood flow through the vessels.
A nocturnal penile tumescence (NPT) test does not cause any discomfort, but you may feel embarrassed about doing the test. Remember that it's important to find the cause of your inability to have an erection and you don't need to feel embarrassed about the test.
During the intracavernosal injection test, you will feel a sharp, stinging pain in your penis from the needle. If you feel a burning or aching pain during the erection, tell your doctor immediately.
The ultrasound does not cause any pain. If you get a medicine or device during the test to cause an erection, you may feel embarrassed and the shot may hurt.
There are no problems from having the nocturnal penile tumescence (NPT) test.
The intracavernosal injection test has a small chance of causing:
There are no problems from an ultrasound test. If a device is used to cause an erection, you may have some mild discomfort. If a shot of medicine is used, you have the same chance for problems as the intracavernosal injection test.
Tests for erection problems can help find a cause for a man's problem in having or maintaining an erection (erectile dysfunction, or impotence).
Tests for erection problems may include blood tests for testosterone, luteinizing hormone, prolactin, and thyroid hormone. A urine test, complete blood count, blood sugar level, and cholesterol and triglyceride levels may also be done.
To learn more about lab tests done for erection problems, see:
An erection has likely occurred if:
An erection has likely not occurred if:
The test is more accurate if repeat tests show the same results.
An erection caused by intracavernosal injection is usually measured on a scale of 0 to 4, with a full erection measuring a 4.
The ultrasound can show if you have blood flow problems as the cause of your erection problems.
Reasons you may not be able to have the test or why the results may not be helpful include:
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|Urology Care Foundation: The Official Foundation of the American Urological Association|
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UrologyHealth.org is a website written by urologists for patients. Visitors can find specific topics by using the "search" option.
The website provides information about adult and pediatric urologic topics, including kidney, bladder, and prostate conditions. You can find a urologist, sign up for a free quarterly newsletter, or click on the Urology A–Z page to find information about urologic problems.
Other Works Consulted
- Bella AJ, Lue TF (2008). Male sexual dysfunction. In EA Tanagho, JW McAninch, eds., Smith's General Urology, 17th ed., pp. 589–610. New York: McGraw-Hill.
- Burnett AL (2012). Evaluation and management of erectile dysfunction. In AJ Wein et al., eds., Campbell-Walsh Urology, 10th ed., vol. 1, pp. 721–748. Philadelphia: Saunders.
|Primary Medical Reviewer||E. Gregory Thompson, MD - Internal Medicine|
|Specialist Medical Reviewer||Christopher G. Wood, MD, FACS - Urology, Oncology|
|Last Revised||May 14, 2012|
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