The urodynamic evaluation is actually several tests performed at the same time to provide important data regarding the function of the bladder and pelvis.
This test is performed in situations were a patient has complex voiding dysfunction issues, incontinence and difficulty emptying. It is performed on both men and women. The test is generally performed using a computer system that can aid in interpretation of the data obtained during the study.
The test is performed in our office and requires no sedation or premedication. There is no particular preparation necessary but we would ask that any medications designed to affect bladder function be stopped 3 days prior to the study. The procedure will require approximately an hour of time. You will be able to drive yourself to and from the procedure
The test requires use of very small urethral and and rectal catheter. Also, small electrode patches are placed on the skin between the anus and vagina or scrotum. The patient sits on a special chair that allows urine to flow into a funnel at the base of the chair facilitating measurement of urine flow. Fluid is instilled into the bladder using the bladder catheter at a constant rate until the patient is full then the patient is asked to urinate to completion. The test is more unusual and odd and not very uncomfortable.
The pressure measured in the rectal catheter is subtracted from the pressure measured in the bladder catheter to give the detrusor pressure. This is the “true” bladder pressure and is the pressure used for interpretation. Numbers derived from the detrusor pressure include the bladder pressure at capacity and pressure during maximum voiding. During voiding the maximum and average flow rate are calculated and the maximum flow is compared to the detrusor pressure during maximum flow to arrive at the pressure flow analysis. Activity from the surface electrodes is assessed during the procedure to give the electromyogram (EMG) of the pelvic floor muscles and urethra. The patient is generally asked to bear down and cough during the procedure to see if leakage occurs and to determine valsalva leak point pressures.
What is important from this study is to find out abnormalities during filling and emptying. Abnormal contractions in the bladder during filling are referred to as detrusor overactiviity. High pressure during voiding, especially in the setting of low urine flow is suggestive of obstruction. Elevated EMG activity during voiding suggests discoordination of pelvic events. Low pressure leakage is suggestive of intrinsic sphincteric deficiency.
The patterns of abnormalities found on the study often give indication of the type of issue leading to the voiding dysfunction experienced by the patient. With this information, more accurate diagnosis and treatment are possible.