A small tube is placed in the bladder to record pressure. Another tube may be placed in the rectum to record abdominal pressure. Once the bladder is emptied completely, the bladder is filled slowly with sterile 0.9% saline water. During this time, the person is asked to describe how the bladder feels and indicate when the need to urinate arises. When the urge to urinate occurs, the volume of water and the bladder pressure are recorded. The person may be asked to cough during this procedure to see if the bladder pressure changes. A cystometric test can also identify involuntary and inappropriate bladder contractions.
These tests are performed under general anaethesia
for very young children.
Electromyography uses special sensors to measure the electrical activity of the muscles and nerves in and around the bladder and the sphincters.
A sensor is placed on each side of the anus and one on the thigh. Electrical activity related to muscle is recorded on a machine.
Postvoid Residual Measurement
This urodynamic test measures the amount of urine left in the bladder after urination.