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Urodynamics (Bladder Pressure Study)

What is Urodynamics?

Urodynamics is an outpatient study that evaluates the function of the bladder. If done in conjunction with imaging (x-rays or ultrasound), it can also identify structural abnormalities. This test is not painful and is done under local anaesthetic with the patient awake, so that the patient can follow instructions and give feedback during the study. Urodynamics is now the mainstay diagnostic method, especially in objectively identifying complex bladder problems.

Why is it done?

Indications for this study:

  1. If diagnosis is unclear after history and examination

  2. Confirm diagnosis before drug treatment in those more susceptible to side-effects

  3. Confirm diagnosis before invasive treatment

  4. Failed empirical drug/surgical therapy

  5. Provide prognostic information before treatment

  6. Clinical follow-up (e.g. neuropathic bladder)

If you want to know whether a urodynamics study can help you contact us.

How is it done?

The study normally takes about 45 minutes. After an initial void, a small catheter (pressure line) is inserted into the bladder and another one into the rectum. These lines are connected to a computer and they detect the pressures in the bladder with high accuracy. There are 2 phases to this test – the filling phase and the voiding phase.

Filling phase

During the filling phase, a sterile fluid mixed with contrast is trickled into your bladder. You will be asked to report on the sensations and degree of urgency as your bladder is filled. You should do your best to hold the fluid in. This phase will test for:

Does your bladder have normal sensation?

  • Can your bladder stretch without a rise in pressure during filling?

  • Overactivity of the bladder

  • Leakage from strong bladder urgency

  • What is your estimated bladder capacity?

  • You may be asked to do a series of cough, stand or bear down to test for stress leakage.

  • X-rays or ultrasound can look for:

    • Shape of the bladder

    • Reflux of urine up the ureters and kidneys

Voiding phase

During the voiding phase, you will be asked to do a ‘normal’ void. This phase will test for:

  • How well your bladder can contract

  • Bladder outlet obstruction (eg. from an enlarged prostate)

  • X-rays or ultrasound can look for:

    • The degree of bladder neck support during voiding (important in patients with stress urinary incontinence)

    • How well the bladder neck opens up during voiding

    • How much urine is left behind after a void

The small catheters are then removed at the end of the study.

How do I prepare for it?

  • Before the study, you may be asked to complete a bladder diary or a questionnaire.

  • You should arrive with a comfortably full bladder, so that we can start with measurements of a first void.

  • Your doctor may ask you to either continue or discontinue some of your bladder medications in the lead-up to this study.

  • You do not need to fast before the test. You can resume all normal activities, including driving after the study.

  • If you have a urinary tract infection, this test should be postponed.

How do I arrange to have this study done?

Your family doctor or your medical specialist (urologist, gynaecologist, urogynaecologist, neurologist, geriatrician etc.) can refer you to have this study done. Doctors can submit the online form Patient Referral – Urodynamics.