Testing of the bladder to determine the cause of problems is called “Urodynamics”. This actually refers to a group of procedures that are performed to examine voiding (urinating) problems. The goal of the testing is to determine the cause of bladder control issues.
The testing focuses on the bladder’s ability to fill and empty steadily and completely. It also can show whether or not the bladder is having abnormal contractions, which cause leakage. The urodynamic test is a precise measurement using sophisticated instruments.
Before the Test
You will not need any special preparation for the test. We want you to have some urine in your bladder for the first part of the test, so don’t empty your bladder just before you come to the appointment. You do not have to drink any specific amount before the test. Please do not drink caffeine or take any bladder-related medications that day.
The testing includes:
A uroflowmeter measures the amount of urine and the flow rate (how fast the urine comes out). This creates a graph that shows changes in flow rate from second to second so the doctor or nurse can see the peak flow rate and how many seconds it took to get there. This test will be abnormal if the bladder muscle is weak or urine flow is obstructed.
After you’ve finished urinating, you may still have some urine remaining in your bladder. To measure this urine, called a “post-void residual”, the doctor will insert a very tiny catheter into your bladder, drain the urine and measure it. A 100 ml or more may indicate a problem that could require further testing. This involves a mild pinching sensation at the opening of the bladder.
Cystometry (cystometrogram – CMG)
The doctor will use the same catheter to fill your bladder slowly with body concentration saltwater. A cystometrogram (CMG) measures how much your bladder can hold, how much pressure builds up inside your bladder as it stores urine, and how full it is when you feel the urge to urinate. Another catheter will be placed in the vagina to record pressure there also. You will be asked how your bladder feels and when you feel the need to urinate. The volume of water and the bladder pressure will be recorded. You will be asked to cough or strain during this procedure. Sometimes the bladder will have abnormal spasms which can be identified with this test.
Measurement of leak point pressure
While your bladder is being filled for the CMG, it suddenly may contract and squeeze some water out without warning. The equipment will record the pressure at the time of the leak. This reading tells the doctor about the kind of bladder problem you have.
After the CMG, the catheter can measure the pressures generated by the muscle that holds urine in. This pressure study helps to identify weakness in the muscle sphincter which helps determine what might be the best way to improve the bladder function.
You might have mild discomfort after these tests. Most patients don’t. There is a very small risk of bladder infection following the test. Drinking plenty of fluids, including cranberry juice, should help.
If you have signs of infection, fever, chills or pain, call your doctor.
The doctor will sit down in the office after the test and discuss the results and what strategy might be the best to improve your bladder function.