Voiding Cystourethrogram

Test Overview

A voiding cystourethrogram (say "sis-toh-you-REE-throh-gram") is a test that is done to see if there are problems with the urinary system and to see how urine flows out of the bladder. This test, also called a VCUG, uses contrast fluid and X-rays so the doctor can see how the bladder fills and drains.

A VCUG can show if urine from the bladder is flowing back up toward the kidneys. This is called vesicoureteral reflux, or VUR.

For this test, a thin, flexible plastic tube called a catheter is placed through the urethra into the bladder. A contrast liquid flows through the catheter to fill the bladder. X-rays are taken while the bladder fills and then empties. The catheter slips out or is removed once the bladder is empty.

Why It Is Done

This test is done to:

  • Find the cause of urinary problems. These include repeated urinary tract infections and not being able to control when you urinate (urinary incontinence).
  • Check for vesicoureteral reflux, which means urine backs up toward the kidneys from the bladder instead of going through the urethra and out of the body.
  • Check for structural problems of the bladder and urethra.
  • Follow up on other problems found during a different test such as a CT scan of the urinary system.

How To Prepare

Having a test can be stressful. This information will help you understand what you can expect. And it will help you safely prepare for your test.

Preparing for the test

  • Tell your doctor if you are allergic to iodine. Iodine is usually used in the contrast material that the doctor will put in your bladder.
  • Tell your doctor if you are or might be pregnant. Your doctor may not do the test if you are pregnant. That's because the X-rays could harm an unborn baby.
  • Understand exactly what procedure is planned, along with the risks, benefits, and other options.
  • Tell your doctor ALL the medicines, vitamins, supplements, and herbal remedies you take. Some may increase the risk of problems during your procedure. Your doctor will tell you if you should stop taking any of them before the procedure and how soon to do it.
  • If you take a medicine that prevents blood clots, your doctor may tell you to stop taking it before your procedure. Or your doctor may tell you to keep taking it. (These medicines include aspirin and other blood thinners.) Make sure that you understand exactly what your doctor wants you to do.

How It Is Done

  • The nurse will ask you to take off all or most of your clothes. Then you will cover yourself with a cloth or paper covering.
  • You will urinate just before the test starts.
  • You will lie on your back on an X-ray table, and a standard X-ray will be taken of your belly and pelvic area.
  • Your genital area will be cleaned and covered with towels. A flexible, thin tube will be inserted through your urethra into your bladder. This tube is called a catheter.
  • The doctor will put a liquid into your bladder through the catheter. This liquid is called contrast material. It shows up well on X-ray pictures.
  • X-rays will be taken while your bladder is filled with liquid and as the liquid drains out. You may be asked to stop urinating, change positions, and start urinating again.
  • Your bladder may be filled a second time. The catheter may slip out by itself while your bladder is draining. If not, it will be removed.
  • Once your bladder is empty, a final X-ray is usually taken.

How long the test takes

This test usually takes 30 to 45 minutes.

How It Feels

This test isn't painful, and you won't feel anything when the X-rays are taken.

You may find it somewhat uncomfortable when the catheter is inserted and while it's in place. You will have a feeling of fullness in your bladder and an urge to urinate when the contrast liquid fills your bladder.

You may be a little sore afterward from the catheter. If so, soaking in a warm tub bath may help.


A voiding cystourethrogram (VCUG) usually doesn't cause problems. Once in a while, this test may lead to a urinary tract infection. If the contrast material is injected with too much pressure, there is some chance of damage to the bladder or urethra.

There is always a slight risk of damage to cells or tissue from being exposed to any radiation, including the low levels used in this test. But the risk of damage from the X-rays is usually very low compared with the benefits of the test.

Some people may have an allergic reaction to the contrast material.


Some results may be available immediately after the cystourethrogram. Final results are usually available within 1 to 2 days.

Voiding cystourethrogram (VCUG)


The bladder appears normal.

Urine flows normally from the bladder.

The bladder empties all the way.

The contrast material flows evenly out of the bladder through a smooth-walled urethra.


Bladder stones, tumors, narrowing or pouches in the wall (diverticula) of the urethra or bladder are seen in the bladder.

If the test was done because of possible injury to the bladder, a tear is found in the bladder wall or urethra.

Urine flows backward from the bladder into the ureters (vesicoureteral reflux).

Contrast material leaks from the bladder.

The bladder does not empty all the way.

The prostate is enlarged.


Current as of: November 15, 2023

Author: Healthwise Staff
Clinical Review Board
All Healthwise education is reviewed by a team that includes physicians, nurses, advanced practitioners, registered dieticians, and other healthcare professionals.