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.
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
Other tests that may be done as part of a physical exam
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
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:
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.
Health Tools help you make wise health decisions or take action to improve your health.
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
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.
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
The types of devices you can use include:
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
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
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.
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.
no problems from having the nocturnal penile tumescence (NPT) test.
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:
has likely occurred if:
An erection has likely not occurred if:
The test is more accurate if repeat tests show the same
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:
The National Kidney and Urologic Diseases Information
Clearinghouse (NKUDIC) provides information about diseases of the
kidneys and urologic system to people with these problems and to
their families, to health professionals, and to the public. NKUDIC answers
inquiries; develops, reviews, and distributes publications; and works closely
with professional and patient groups and government agencies to
coordinate resources about kidney and urologic diseases.
NKUDIC, a federal agency, is a service of the National
Institute of Diabetes and Digestive and Kidney Diseases (NIDDK). NIDDK is part
of the National Institutes of Health under the U.S. Department of Health and
UrologyHealth.org is a website written by urologists
for patients. Visitors can find specific topics by using the "search"
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.
May 14, 2012
E. Gregory Thompson, MD - Internal Medicine
& Christopher G. Wood, MD, FACS - Urology, Oncology
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