Cystometry is a test of bladder function in which pressure and volume of fluid in the bladder is measured during filling, storage, and voiding.
A cystometry study is performed to diagnose problems with urination, including incontinence, urinary retention, and recurrent urinary tract infections. The urinary bladder stores urine produced by the kidneys. The main muscle of the bladder wall, the detrusor, relaxes to allow expansion of the bladder during filling. The urethra,
the tube through which urine exits, is held closed by a ring of muscle known as the urethral sphincter. As volume increases, stretching of the detrusor and pressure on the sphincter sends signals to the brain, indicating the need for urination, or voiding. Voluntary relaxation of the sphincter and automatic contractions of the detrusor allow successful and virtually complete voiding.
Urinary difficulties may occur because of weak or hyperactive sphincter or detrusor, or non-coordination of their two activities. Infection of the bladder or urethra may cause incontinence, as can obstruction of the urethra from scar tissue, prostate enlargement, or other benign or cancerous growths. Loss of sensation due to nerve damage can lead to chronic overfilling.
The mild irritation of the urinary tract necessary for insertion of the catheter may occasionally cause flushing, sweating, and nausea. Cystometry is contraindicated in patients with urinary tract infection because of the potential for false results and the possibility of exacerbating the infection.
Maggie Boleyn R.N., B.S.N., The Gale Group Inc., Gale, Detroit,