What are Urodynamic Tests?
Urodynamic tests study the storage of urine within the bladder and the flow of urine through the lower urinary tract to the outside of the body. These tests are done on the lower urinary system which consists of the bladder, urethra, and the voluntary sphincter muscles. Men have a gland called the prostate gland, which can affect urination.
The tests are ordered by your physician if he or she suspects a problem in these areas. The test will show if the muscles and the nerves needed to urinate are working properly.
How does the Lower Urinary Tract Work?
The bladder is a hollow organ surrounded by a muscle. From the kidney, urine travels down tubes called the ureters into the bladder for storage. The bladder fills up much like a balloon. When it is time for you to empty your bladder, your brain sends signals through the nerves to the sphincter muscles, a complex mechanism that is composed of an active and a passive muscle. The external sphincter muscle (or active sphincter) relaxes and opens, like untying a knot. Then the bladder contracts, which can be compared to making a fist with your hand and squeezing it. Next, the internal (or passive sphincter) muscle relaxes and urine passes from the bladder down a tube called the urethra to the outside of the body.
What are the Types of Tests?
Uroflow (flow study) – The uroflow will be done first. It will record the amount of urine, the time it takes to urinate, the speed of your stream, and whether or not it is strong or forceful. The test will be done on a special urodynamic chair. After voiding a catheter will be inserted to see how well you empty your bladder.
Cystometrogram (CMG) – For this test, a very small catheter will be inserted into the bladder. This will measure the pressure in your bladder during various stages; and it also serves as a way to infuse fluid. It will test how well your bladder muscle stretches during filling, how well it stores fluid, and how well you empty your bladder. A small tube will be placed in your rectum. This is necessary so we can isolate the pressure of the bladder muscle itself. You will be seated in a specially designed chair as we begin filling your bladder with sterile water. During the filling stage you may be asked to cough at certain times. You will also be asked to tell us when you feel your first urge to void and again when you are very full and unable to hold it any longer. Next you will be asked to relax and void. This test may be repeated depending on the results.
If your doctor has ordered video urodynamics, we will use a contrast dye to fill your bladder and the test will be done with the use of X-ray equipment. During the video urodynamics you will be able to see your bladder on a screen, similar to a TV screen, during each stage of the procedure.
Electromyograph (EMG) – The EMG is done at the same time as the CMG. In order to do this, patches are placed on either side of the rectum to test the muscle activity.