What Is a Urodynamic Test and How Is It Done?

Reviewed on 1/30/2021

What is the purpose of a urodynamic test?

A doctor may advise a urodynamic test for people who experience urine leakage, recurrent UTIs, frequent urination, and painful urination.
A doctor may advise a urodynamic test for people who experience urine leakage, recurrent UTIs, frequent urination, and painful urination.

A urodynamic test is done to study the function of the lower urinary tract (bladder and its draining tube called the urethra) and how this relates to a patient's urinary symptoms. This aims to test the capacity of the bladder and urethra to work in coordination for holding and voiding urine steadily and completely. The urodynamic test is advised in patients with the following signs and symptoms:

  • Urine leakage
  • Frequent urination
  • Recurrent urinary infections
  • Pain during urination
  • Sudden urge to urinate and problem in starting urination or completely emptying the bladder

Details of the procedure:

  • The test is performed as a day care procedure and usually takes 30-40 minutes. The patient may have minimal discomfort; however, they need to be awake and cooperative during the test.
  • The test will be supervised by a doctor who will be assisted by nurses. Sometimes, a radiographer would also be present for an X-ray or ultrasound.
  • First, the doctor will measure the urine flow rate of the patient. They will ask the patient to urinate into a flow rate machine to measure the strength of the urinary stream.
  • The radiologist will then conduct an ultrasound scan to assess how well the bladder empties.
  • The doctor may then ask the patient may to lie on a couch or bed. They will insert a catheter (fine soft plastic tube) through the urethra into the bladder using local anesthetic jelly to help it slide in with minimal discomfort. They use the catheter to fill the bladder and measure the fluid pressure in the bladder.
  • The doctor will then place a second fine catheter in the patient's rectum (back passage) to measure the pressures in their abdominal cavity.
  • The doctor will tape all the catheters (once all are in place) to the patient's leg and connect them to transducers that will continually measure the pressures and relay the information to specialized computer software for recording and analysis.
  • The doctor will then fill the bladder slowly with sterile saline through the catheter.
  • The doctor may ask the patient to cough and strain during the test when the patient feels the first desire to pass urine.
  • If one of the symptoms is urinary incontinence (leakage), the doctor will try to reproduce this using various measures. The patient should not be embarrassed about this; reproducing the symptoms will help the doctor determine the cause of their problem.
  • The doctor will encourage the patient to hold on until their bladder feels very full.
  • To finish the test, the doctor may ask the patient to stand or sit and pass urine into the flow rate machine again. Once completed, the doctor will remove all the catheters.
  • At this point, the doctor will usually perform a flexible cystoscopy to visually inspect the bladder.
  • Analyzing the study does take time, so the doctor will schedule a follow-up appointment later for the patient to discuss the results. The urodynamic test will help determine the cause of urinary symptoms and will greatly assist in choosing the most appropriate treatment.
  • After the procedure, the patient may need to drink about double their normal fluid intake for 24-48 hours to help reduce the risk of infection.
  • The doctor may prescribe a course of antibiotics if they suspect a high risk of urinary infection.

Possible risks:

Common:

  • Some mild discomfort or burning sensation when passing urine for a few days

Occasional:

  • Some mild bleeding in the urine

Rare:

  • Infection in urine that requires antibiotics or, very rarely, septicemia that requires hospital admission
  • Inability to pass the catheter into the bladder, so the test must be abandoned and further tests need to be arranged
  • Urinary retention (inability to empty your bladder) requiring a temporary catheter to be reinserted into the bladder to relieve discomfort
  • Failure to find the cause of the signs and symptoms, requiring a possible repeat of the test

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References
Gill, B.C. "Urodynamic Studies for Urinary Incontinence." Medscape.com. Dec. 11, 2019. <https://emedicine.medscape.com/article/1988665-overview>.

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