Saturday, April 05, 2008

Urodynamic Studies: Who, when, & why.

The bladder does 2 things; it fills and it empties. All urinary problems can be grouped into problems of bladder filling or bladder emptying. For example incontinence--leakage of urine--can be due to inability to hold the urine in or due to inability to empty the bladder. Often, all that a urologist needs to diagnose and treat the problem is a good history and physical examination. However, on occasionally, the patient's symptoms and signs point in different directions and this makes it difficult for the urologist to come to an accurate diagnosis and hence treatment plan for the patient. In these cases, urodynamic studies may be helpful.

Urodynamic studies test the bladder as a functional unit. The test has 5 parts:
  • CMG--the CystoMetroGram tests the bladder ability to fill. It measures the bladder compliance and the bladder pressures. The doctor can also get an assessment of bladder sensory capacity, ie pain with filling, ability to sense fluid presence and temperature, etc.
  • The pressure flow: this tests the bladder ability to generate pressure during voiding and can give an assessment of whether a functional obstruction is present, such as the case in BPH or bladder neck obstruction.
  • The EMG: this records sphincteric activity and measures whether or not a patient can appropriately contract and relax their pelvic musculature. For example, when voiding, EMG activity should decrease and it should increase while coughing. People with chronic pelvic pain conditions often have abnormal EMG patterns.
  • The uroflow: this test records the velocity of the urine flow. People with blockages will typically have slow flow rates. This test is most informative when coupled with a pressure-flow assessment.
  • The PVR: this determines how much urine is left behind after the person has completed the urination. Incontinence can be associated with both high and low PVRs. UTIs can be caused by high PVRs.
Urodynamic studies are useful in the diagnosis and treatment of patients with many urinary disorders. Such conditions include:
  • bladder outlet obstruction/BPH
  • urinary retention
  • urinary incontinence
  • urinary tract infections
  • overactive bladder
  • urinary frequency
  • interstitial cystitis
  • chronic pelvic & perineal pain syndrome
If you suffer from urinary problems and are not helped by empiric therapy, ask your urologist for a urodynamic study for a more accurate diagnostic evaluation.


Dr S