Skip to Content
Home > Wellness > Health Library > Tests for Erection Problems
Tests for erection problems can help find out why a man can't have or maintain an erection. This problem is called erectile dysfunction, or impotence. It's a common male problem. Most erection problems are caused by a mix of blood vessel, nerve, or psychological issues.
find the cause, your doctor will first ask about your
sexual history and do a
physical exam. During this exam, the doctor
Other tests that may be done as part of the exam
If the results of your physical exam and other tests are
normal, your doctor may have you try a medicine that helps cause an erection. If the medicine doesn't help, then you may need more
This topic focuses on three more tests you may have after
the physical exam and lab tests listed above. These three tests are:
test checks to see if a man is having normal erections during sleep. Most men
have 3 to 5 full erections during deep sleep. Men
who don't have erections because of psychological problems can still have
erections during deep sleep. Sometimes, sleep problems or serious
depression can prevent these normal nighttime erections.
This test can be done at home or in a special sleep lab.
Tests are usually done for at least 2 nights in a row.
If good erections occur during sleep, the cause of the erection problems is most likely not physical.
The NPT test may also be called the
stamp test or the rigidity test.
During this test,
the doctor injects a medicine into the side of the
penis to make an erection. The fullness of the erection
and how long the erection lasts are measured.
Doppler ultrasound uses a handheld tool that is passed gently over the
penis. The tool uses reflected sound waves to show blood flow on a computer screen.
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 out if the cause of an erection problem is physical,
psychological, or both.
Physical causes include:
Psychological tests may be needed if no physical cause is
found for an erection problem. Psychological causes of erection problems may
Before the test, do not take
any medicines that cause an erection. These medicines include sildenafil (Viagra), tadalafil
(Cialis), and vardenafil (Levitra).
Do not drink
alcohol or take sleeping pills for 2 days before you have an NPT test. The alcohol and the pills can change your deep sleep time. This can affect nighttime erections.
Tell your doctor if you:
You may be asked to avoid
products with 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. Keep your
pubic hair inside the underwear out of the way. Put the device around your
penis. After you put on the device, carefully put your penis inside your
The types of devices you can use include:
This 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. 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. 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. The band is 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
similar medicine may also be placed into the
urethra, the tube through which urine leaves the
penis. This is called an intraurethral injection.
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 arousing movies or to massage your penis to cause an
erection. Your doctor will measure how rigid the erection is and how long it 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 exam table. Your doctor may need to inject a medicine or use a soft
band around the penis to cause an erection. This lets the doctor see blood flow through the
An NPT test does not cause any discomfort. But you may feel
embarrassed about doing the test. Remember that it's important to find the reason you are not able to have an erection. You don't need to feel
During the test, you will feel a sharp sting in your penis from the needle. If you feel a burning or aching pain during
the erection, tell your doctor right away.
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. The shot may hurt a bit.
no problems from having the NPT test.
This 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 pain. 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 out why a man can't have or maintain an erection. This problem is called 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 is usually measured on a scale of 0 to 4. A full erection is a 4.
The ultrasound can show if you
have blood flow problems as the cause of your erection problems.
You may not be able to have the test, or the results may not be helpful, if:
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.
ByHealthwise StaffPrimary Medical ReviewerE. Gregory Thompson, MD - Internal MedicineAdam Husney, MD - Family MedicineSpecialist Medical ReviewerChristopher G. Wood, MD, FACS - Urology, Oncology
Current as ofMay 24, 2016
Current as of:
May 24, 2016
E. Gregory Thompson, MD - Internal Medicine & Adam Husney, MD - Family Medicine & Christopher G. Wood, MD, FACS - Urology, Oncology
To learn more about Healthwise, visit Healthwise.org.
© 1995-2016 Healthwise, Incorporated. Healthwise, Healthwise for every health decision, and the Healthwise logo are trademarks of Healthwise, Incorporated.
I Want To...
Our interactive Decision Points guide you through making key health decisions by combining medical information with your personal information.
You'll find Decision Points to help you answer questions about:
Get started learning more about your health!
Our Interactive Tools can help you make smart decisions for a healthier life. You'll find personal calculators and tools for health and fitness, lifestyle checkups, and pregnancy.
Feeling under the weather?
Use our interactive symptom checker to evaluate your symptoms and determine appropriate action or treatment.