What is the test?
By filling your bladder with a liquid dye that shows up on x-rays, your doctor can watch the motion of your bladder as it fills and empties and can see if your urine splashes backwards toward your kidneys as the bladder muscle squeezes. This kind of test can help your doctor to better understand problems with repeated urinary tract infections or problems involving damage to the kidneys. It can also be useful for evaluating urine leakage problems.
How do I prepare for the test?
Tell your doctor before the test if you have ever had an allergic reaction to x-ray dye (IV contrast dye). Also let your doctor know if there is any chance you are pregnant.
What happens when the test is performed?
You wear a hospital gown and lie on a table in the x-ray department. A part of your genital area is cleaned with soap on a cotton swab. Then a soft, bendable rubber tube called a urinary catheter is inserted into your bladder, usually by a nurse. The tube is first coated with a slippery jelly and then pushed gently through the opening of the urethra (at the end of the penis for men and near the opening of the vagina for women).
You will feel some pressure while the tube slides into the urethra. Once it is in place, a tiny balloon on the end of the tube is filled with air to hold it in position. The other end (about 6 inches of tubing) hangs outside of your vagina or penis. The doctor uses this tube to fill your bladder with fluid containing a dye that shows up on x-rays. You will feel pressure in your bladder as it begins to expand.
To create a clear picture, your bladder needs to be filled with as much fluid as it can hold. You will probably feel a very strong urge to urinate. A few pictures are taken with the bladder completely full, and then the small catheter balloon is emptied and the tube is pulled out. You are given a urinal container or a bedpan and asked to urinate while you are still on the table under the x-ray camera. Several pictures are taken while your bladder is emptying. Many patients find this part of the test embarrassing, but you can be reassured that it is a routine part of this common test, something the technicians in this test lab see on a regular basis.
What risks are there from the test?
There is a small chance of having an allergic reaction to the x-ray dye used in the test. Some patients have some temporary irritation of their urethra after the tube has been in place, and this might result in some burning during urination for a few hours afterward. Let your doctor know if burning or pain with urinating lasts longer than a day; this could mean you have developed an infection.
As with all x-rays, there is exposure to a small amount of radiation. The amount of radiation from x-ray tests is very small. So, occasional exposures to x-ray tests are unlikely to be harmful to adults. However, repeated x-ray exposure may increase the risk of cancer later in life.
Pregnant women should avoid this test because the x-rays are directed at the pelvis.
Must I do anything special after the test is over?
How long before the result of the test is known?
The x-rays require an hour or more to be developed, and it takes some additional time for the radiologist to examine the pictures and decide whether they look normal. Your doctor should receive a report within a few days.