Cystometry is a test that measures the pressure inside of the bladder to see how well the bladder is working. Cystometry is done when a muscle or nerve problem may be causing problems with how well the bladder holds or releases urine.
Urination is a complex process. As the bladder fills, nerves in the bladder wall send a message to the spinal cord and brain that you need to urinate. In response, your spinal cord sends a signal for the bladder to contract (voiding reflex). When you hold in your urine, your brain is overriding this reflex. When you allow the reflex to occur, urination occurs. A problem affecting this nerve pathway or the muscles of the bladder wall can cause bladder dysfunction.
During cystometry, your bladder is filled with water or gas to measure its ability to hold in and push out the water or gas. Medicine may also be given to see whether your bladder contracts or relaxes normally in response to the medicine. A small tube (catheter) can be placed in your rectum to measure pressure as the bladder fills. A small pad or needle may be placed near your anus to measure muscle function in this area.
Why It Is Done
Cystometry is done to:
- Find the cause of problems with the bladder or the muscle that holds urine in the bladder (bladder sphincter). Problems in one or both of these areas may cause uncontrolled urine leakage, an urgent feeling that you have to urinate, or a weak urine stream.
- Measure how much urine your bladder can store and how much urine remains in your bladder after you feel you have completely emptied it (residual volume).
- Help you and your doctor make decisions about how to treat your urinary symptoms.
- See how well the bladder works in people with progressive neurological diseases, such as multiple sclerosis.
How To Prepare
Tell your doctor if you:
- Are taking any medicines. Some medicines and herbal supplements can affect bladder function.
- Are or might be pregnant.
- Have symptoms of a urinary tract infection, such as pain or burning with urination, foul-smelling or cloudy urine, or an urge to urinate more often than usual.
Talk to your doctor about any concerns you have regarding the need for the test, its risks, how it will be done, or what the results will mean. To help you understand the importance of this test, fill out the medical test information form(What is a PDF document?).
How It Is Done
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.
- 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.
How It Feels
You may feel embarrassed at having to urinate in front of other people. This procedure is quite routine for the medical staff. If you find yourself feeling embarrassed, take deep, slow breaths and try to relax.
You will feel a strong urge to urinate at times during the test. You may also find it somewhat uncomfortable when the catheter is inserted and left in place, and you may be sore afterward. If so, soaking in a warm tub bath may help.
Cystometry usually does not cause problems. There is always a slight risk of developing a urinary tract infection when a catheter is inserted into the bladder. In rare cases, a bladder infection can spread to a kidney and into the blood, leading to a life-threatening infection. If an infection occurs, it can be treated with antibiotics.
If you have a high spinal cord injury, you may have low heart rate, high blood pressure, headache, and feel flushed or sweaty during the test. Report these symptoms to the health professional conducting the test, since further testing may cause complications.
After the test
After the test, you may need to urinate frequently, with some burning during and after urination for a day or two (especially if carbon dioxide gas was used). Drink lots of fluids to help minimize the burning and to prevent a urinary tract infection.
A pinkish tinge to the urine is common for several days after cystometry. But call your doctor immediately if:
- Your urine remains red or you see blood clots after you have urinated several times.
- You have not been able to urinate 8 hours after the test.
- You have a fever, chills, or severe pain in your flank or abdomen. These may be signs of a kidney infection.
- You have symptoms of a urinary tract infection. These symptoms include:
- Pain or burning upon urination.
- An urge to urinate frequently, but usually passing only small quantities of urine.
- Dribbling or leakage of urine.
- Urine that is reddish or pinkish, foul-smelling, or cloudy.
- Pain or a feeling of heaviness in the lower abdomen.
Cystometry is a test that measures the pressure inside of the bladder to see how well the bladder is working.
Some results may be available right away. Full results are usually available in 1 to 2 days.
The rate at which urine flows from your bladder when you urinate is normal.
The amount of urine left in your bladder after you urinate (residual urine volume) is less than 30 milliliters (mL).
The point at which you first feel the urge to urinate is within the normal range, when the amount of liquid in your bladder is between 175-250 mL.
The point at which you feel you must urinate is within the normal range, when the amount of liquid in your bladder is between 350-450 mL.
The maximum amount of liquid your bladder can hold is within the normal range: 400-500 mL.
Tests of the function of the nerves that control your bladder are normal.
Urine does not leak from your bladder during the stress test.
The rate at which urine flows from your bladder when you urinate is slower than normal, or your urine stream starts and stops.
The amount of urine left in your bladder after you urinate (residual urine volume) is more than normal.
You have trouble starting the flow of urine.
The point at which you first feel the urge to urinate is more or less than normal or does not occur.
The maximum amount of liquid your bladder can hold is less than normal or you can't feel it.
Normal sensations and reactions do not occur when the nerves that control your bladder are tested.
Urine leaks from your bladder during the stress test.
What Affects the Test
Reasons you may not be able to have the test or why the results may not be helpful include:
- Having a urinary tract infection (UTI). Cystometry should not be done if you have a UTI.
- Straining when urinating.
- Not being able to urinate while sitting or lying down.
- Not being able to urinate in front of other people.
- Taking medicines, such as antihistamines and cough and cold medicines, that interfere with your bladder function.
- Having surgery for a spinal cord injury within 6 to 8 weeks before this test.
What To Think About
Other Works Consulted
Chernecky CC, Berger BJ (2008). Laboratory Tests and Diagnostic Procedures, 5th ed. St. Louis: Saunders.
Fischbach FT, Dunning MB III, eds. (2009). Manual of Laboratory and Diagnostic Tests, 8th ed. Philadelphia: Lippincott Williams and Wilkins.
Pagana KD, Pagana TJ (2010). Mosby’s Manual of Diagnostic and Laboratory Tests, 4th ed. St. Louis: Mosby Elsevier.
Primary Medical ReviewerE. Gregory Thompson, MD - Internal Medicine
Specialist Medical ReviewerAvery L. Seifert, MD - Urology
Current as ofAugust 21, 2015