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Erectile Dysfunction Health Center

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Tests for Erection Problems

How It Is Done

Nocturnal penile tumescence (NPT) 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:

  • Snap gauge. A snap gauge is a ringlike device made up of plastic films that fit around the penis. The films break at certain pressures. A snap gauge will break during an erection. It can also tell how firm the penis became during the erection. This test is usually done 2 or 3 nights in a row.
  • Electronic devices. Electronic devices measure changes in the fullness of the penis. The devices have one or more elastic loops that fit around the penis. These are hooked to a small unit that records changes as the loops are stretched.

Intracavernosal injection test

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.

Doppler ultrasound

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.

WebMD Medical Reference from Healthwise

Last Updated: May 14, 2012
This information is not intended to replace the advice of a doctor. Healthwise disclaims any liability for the decisions you make based on this information.

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