Urology Center of Englewood

Cystometrogram (CMG)


The urinary tract includes the kidneys, the ureters, the bladder, and the urethra. The kidneys create urine by filtering the blood and removing waste and excess water. From the kidneys, urine travels to the bladder through small tubes called ureters. Urine is then stored in the bladder until it is passed to the outside of the body through the urethra. The opening of the urethra is at the end of the penis in men, and just in front of the vagina in women.

A cystometrogram (CMG) is a tool that is used to evaluate pressures in the bladder as it fills. This test is one of several that may be used to evaluate how well the lower urinary tract (the bladder and urethra) is storing and releasing urine.

When is a Cystometrogram Needed?

A cystometrogram may be used to evaluate several different urinary problems, including urinary incontinence (leakage of urine); frequent urinary tract infections; frequent urination; sudden, strong urges to urinate; difficulty starting to urinate; or difficulty emptying the bladder completely.[1]

What Can I Expect During and After a Cystometrogram?

You will first be asked to empty your bladder. A small catheter (a thin, hollow tube) will be inserted through the urethra and into your bladder. Another catheter may be inserted in your rectum or vagina. These catheters allow pressures to be measured at various points during bladder filling. As the bladder is filled with sterile fluid, you will be asked to describe what you are feeling. The test allows simultaneous assessment of the actual amount of fluid in the bladder, bladder pressure, and your perception of the bladder filling. Other tests may also be performed, such as tests to measure how fluid leaves your bladder.

After a cystometrogram, you may notice some blood in your urine or slight burning during urination. If these problems persist, you should call your doctor. You should also call your doctor if you notice signs of a urinary tract infection, such as pain or fever.


[1] National Kidney and Urologic Diseases Information Clearinghouse. Urodynamic Testing. NIH Publication No. 12-5106. January 2012.