A urodynamic evaluation is commonly recommended for patients with bothersome urinary symptoms such as frequency, urgency, or incontinence, as well as patients with other diseases such as diabetes or neurologic disease. It is a test used to determine how the bladder is functioning and if there is any evidence of a functional obstruction.
This is an outpatient procedure during which a small catheter is placed into the bladder and a second into the rectum. The bladder catheter measures the pressure inside the bladder and the rectal catheter is used to measure abdominal pressure. The difference between the bladder pressure and abdominal pressure is called the detrusor pressure and is the pressure being exerted by the bladder muscle.
Under normal circumstances, the pressure in the bladder remains low as the bladder fills until it reaches near capacity and then begins to rise. When your brain tells your bladder to begin urinating, the pressure increases to allow the urine to start flowing.
During the study, the bladder is slowly filled and once the patient has a strong urge to urinate, the voiding phase begins and the urine flow and bladder pressure are measured, as well as the residual urine left in the bladder. Urodynamics provide a great deal of information about what the underlying cause of urinary symptoms may be.