Urodynamics is the investigation of functional disorders of the lower urinary tract, including the bladder and the urethra, using physical measurements such as urine pressure and flow rate as well as clinical assessment. For example, a patient complaining of urinary urgency, with increased frequency of urination can be said on the basis of their symptoms to have overactive bladder syndrome. The cause of this might be detrusor overactivity, in which the bladder muscle (the detrusor) contracts unexpectedly during bladder filling. Urodynamics can be used to confirm the presence of detrusor overactivity, which may help guide treatment. Most tests begin with the insertion of a urinary catheter/transducer following with complete bladder emptying by the patient. The urine volume is measured (this is the post-void residual volume, which shows how efficiently the bladder empties) and sent for microscopy and culture to check for infection. Depending on the issue, common tests conducted are:
Free Uroflowmetry: measures how fast the patient can empty his/her bladder.
Multichannel Cystometry: measures the pressure in the rectum and in the bladder, using two pressure catheters, to deduce the presence of contractions of the bladder wall, during bladder filling, or during other provocative maneuvers. The strength of the urethra can also be tested during this phase, using a cough or Valsalva maneuver to confirm genuine stress incontinence.
Pressure Uroflowmetry: measures the rate of voiding, but with simultaneous assessment of bladder and rectal pressures. Helps demonstrate the reasons for difficulty in voiding.
The tests are most often arranged for men with enlarged prostate glands, and for women with incontinence that have either failed traditional treatment or requires surgery.