How It Is Done

Cystometry is done in a doctor's office or hospital urology department by a urologist, gynecologist, or other trained health professional.

You will need to take off most of your clothes below the waist. You will be given a cloth or paper covering to use during the test.

• At the beginning of the test, you will be asked to urinate into a toilet that is connected to a machine called a uroflowmeter. This machine measures how much urine passes and how long it takes. The time and effort needed to start the flow of urine, the number of times you start and stop the flow of urine, and the presence of dribbling near the end of urinating are also recorded.
• Next, you will be asked to lie on your back on an examining table. After the urethra is thoroughly cleaned, a well-lubricated thin, flexible tube (catheter) is gently inserted and slowly moved into your bladder. Any urine remaining in your bladder (residual volume) will be drained and measured.
• Next, a catheter is used to fill your bladder with sterile, room-temperature water. The catheter is also attached to a device called a cystometer, which measures how much your bladder can hold and the pressure in your bladder. You will be asked to report any feelings such as warmth, bladder fullness, or an urge to urinate. The process may be repeated.
  • Sometimes a gas (usually carbon dioxide) is used instead of water.
  • A contrast material may be used if X-rays are taken during the test.
• Another catheter may be placed in your rectum to measure the pressure in your abdomen as your bladder fills. A small pad or needle may be placed near your anus to measure muscle function in this area.
• Each time your bladder is filled, you will be asked to report when you first feel the urge to urinate. Your bladder will then continue to be filled until you report that you feel you must urinate. Then the catheter will be used to drain the bladder, or you will be asked to urinate.
• After all the liquid is drained out of your bladder, and if no additional tests are required, the catheter is removed.

While the catheter is in place, other tests may also be done to help find out whether the nerves that control urination are working properly. These include:

• Ice water test. Ice-cold water is injected through the catheter into your bladder.
• Bethanechol sensitivity test. Bethanechol is a medicine that normally makes the bladder muscles contract. In this test, bethanechol will be injected under your skin.
• Bulbocavernosus reflex test. To test nerve function, a gloved finger is inserted into your rectum and then the penis or clitoris is gently squeezed.
• Saddle sensation test. The skin around your anus is stroked or lightly pricked with a pin.
• Maximum urethral closure pressure (MUCP). Urethral pressure is recorded as the catheter is gently pulled out of your urethra. This test helps determine whether the muscles around the bladder and urethra are functioning properly.
• Leak point pressure (LPP). Approximately 200 mL (7 fl oz) of sterile water is injected into the catheter in your bladder, and then the pressures are measured while you bear down (as if having a bowel movement). This test helps find out whether the muscles around the bladder and urethra are working properly. A low pressure reading may mean that poor muscle function is causing urinary incontinence.

Another test that may be done is the stress incontinence test. In this test, your bladder is filled with water and the catheter is withdrawn. You are then asked to cough, bend over, or lift a heavy object. Dribbling urine means stress incontinence.

Cystometry testing usually takes 30 to 60 minutes, but it may take slightly longer if any of the special tests are done.

After cystometry, you will need to keep track of how much you drink and how much you urinate for the next 24 hours. A burning sensation during urination is a common but temporary side effect. Drinking lots of fluids will help relieve this sensation. You may be given an antibiotic to help prevent a urinary tract infection.