Urodynamics (UDS) is a test that measures your urinary flow, bladder and abdominal pressures when urinating and pelvic floor muscle contractions. The purpose of the test is to identify the cause of your urinary urgency and possible urinary leakage. Your symptoms may occur because the bladder muscle is contracting when you don’t want it to (urge incontinence), the pelvic muscles that keep you dry may be weak and leakage occurs when you cough or are active (stress incontinence) or a combination of both.
UDS is a diagnostic procedure that can be done with minimal irritation. Patients do not need to stop any medications prior to UDS and there is no need to stop eating or drinking prior to the procedure.
Procedure
Prior to the test, urinalysis will be done to rule out a urinary tract infection (UTI). If a UTI is present, we will treat the UTI and reschedule the test for another day. Having the UDS with a UTI can be very painful, puts you at risk for worsening the infection and can affect the results.
The initial phase of the testing involves a uroflow exam. This requires you to urinate into a special device that will show us how rapidly your urine flows. The voiding time, voiding rate and pattern of flow helps us determine what may be wrong with your bladder and the way you urinate.
The next phase of urodynamics involves the cystometrogram. A cystometrogram gives us information about bladder sensation, bladder compliance (the ability of the bladder to stretch), bladder capacity, unstable bladder contractions and urinary incontinence.
In order to perform adequate urodynamics it is necessary to insert pressure sensing catheters. We will need to place one catheter into the urinary bladder through the urethra which will not only measure pressures, but also be used for bladder filling. A second pressure sensing catheter will be place in the rectum(or vagina in some women) in order to obtain correct pressure measurements and avoid artifacts from tightening up or pushing with your abdominal muscles.
Additionally we will place small conductive pads around the urethra to determine the electrical activity of the urethra. When you urinate, the urethra is supposed to relax and not squeeze and we need to see if this is happening.
Once everything is setup you are sitting in a special chair tilted slightly back and then we slowly fill your bladder with fluid about an ounce per minute. We ask you when you first feel that we are filling your bladder and then when your bladder is so full that you cannot hold anymore fluid. At that point we will stop filling your bladder. We will then ask you to perform a series of actions and check for leakage.
The final phase of urodynamic testing involves a pressure flow voiding study. During pressure flow urodynamics simultaneous measurements of bladder pressure, urinary flow rate and urinary sphincter activity will provide the provider with information regarding bladder contractility, outlet obstruction and coordination between the bladder and sphincter muscle.
Risks of urodynamics
The primary risks of urodynamic testing involve the placement of the catheter with a minor risks of infection, bleeding, discomfort and an increase in bladder irritability.