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 to measure its ability to hold in and push out the water. 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.