Urodynamics is commonly known as a bladder function test, or bladder pressure test. It 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 is then called video-urodynamics or fluoro-urodynamics.

This test is not painful and is performed under local anaesthetic with the patient awake so they can follow instructions and give feedback during the study. Urodynamics is the mainstay diagnostic method, especially in objectively identifying complex bladder problems.


Why is it done?

Indications for this study:

  • If the diagnosis is unclear after history and examination.
  • Confirm diagnosis before drug treatment in those more susceptible to side-effects.
  • Confirm diagnosis before invasive treatment.
  • Failed empirical drug/surgical therapy.
  • Provide prognostic information before treatment.
  • Clinical follow-up (e.g., neurogenic bladder).

How is it done?

You are asked to arrive an hour before the start time so the nurses can check you in and get you changed. The study normally takes about 45 minutes, which is followed by about 5 to 15 minutes of discussion at the end. In total, you will spend about 2 hours in the hospital.

Flexible cystoscopy

With the aid of local anaesthetic gel, a small flexible scope may be used to inspect the bladder at the start, before the urodynamics test. It often gives additional information for the doctor, to help get the correct diagnosis. This part only takes a few minutes.

Placing the lines

After the bladder is emptied, a small 2mm-wide pressure line is inserted into the bladder and a small balloon line into the rectum. These lines are connected to a computer and they detect the pressures in the bladder and abdomen with high accuracy. Once they are in place, they do not cause continuous discomfort. The lines will only stay in for about 20 minutes during which they will just quietly measure pressures. You will only be exposed during the first 5 to 10 minutes, when the lines are being placed. Following that you will be covered up and moved to a sitting position.

There are 2 phases to the urodynamics 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:

  • Normal sensation of your bladder.
  • The ability of your bladder to stretch without a rise in pressure during filling.
  • Overactive bladder.
  • Leakage from strong bladder urgency.
  • Estimated bladder capacity.
  • You may be asked to do a series of cough, stand or bear down to test for stress urinary incontinence.
  • X-rays or ultrasound can look for the shape of the bladder, and the reflux of urine up the ureters and kidneys.

Voiding phase

During the voiding phase, you will be asked to do a ‘normal’ void, usually without abdominal straining.

This phase will test for:

  • How well your bladder can contract.
  • Bladder outlet obstruction (e.g., from an enlarged prostate).
  • X-rays or ultrasound to 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 two small lines are then removed at the end of the study.

After this, you will be led to a toilet in the recovery area where you can change back into your own clothes. Then, you will be taken to a waiting area where some snacks and refreshments will be served. Your doctor will then come around to discuss the results with you and your family members.

How do I prepare for the study?

  • Before the study, you may be asked to complete a bladder diary or a questionnaire.
  • 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. You do not need someone to pick you up after the study if you intend to go on your own.
  • You do not need a full bladder at the start of the study.
  • If you have a urinary tract infection, this test should be postponed.
  • Inform us if you have any allergies (e.g., latex or contrast allergy).

What should I expect during the study?

We respect every patient’s privacy and you can expect us to be very watchful about minimising exposure, and keeping you covered up as much as possible.

We understand that you may feel embarrassed with your bladder condition (e.g., urinary incontinence). However, we are doing this test for a reason; to be able to diagnose the problem and help you with its treatment. Sometimes, it may be necessary for the doctor to reproduce the problem during the test, in order to diagnose it.

The amount of radiation from the Xray that we use during the test, is very minimal. But if you are pregnant or concerned about this, please inform us.

What should I expect after the study?

Most patients do not get any side effects from the study. The first few initial voids may feel slightly irritated, but this should settle down. Ural sachet drinks may help with this.

There is a small risk of a bladder or urine infection after the study. The symptoms to look out for are: persistent burning during voiding that gets worse after 1- 2 days, cloudy smelly urine and an increased need to void. If this is happening, you should see your GP to get the urine tested in case you need to go on oral antibiotics.

Sometimes, you may be discharged with an antibiotic script by your doctor after the study, to be taken preventatively or only if needed.

How do I arrange to have this study done?

Your family doctor, your medical specialist (urologist, gynaecologist, urogynaecologist, neurologist, neurosurgeon, rehab physician, geriatrician etc.) or continence nurse can refer you to have this study done.

Doctors can submit the online form Patient Referral – Urodynamics.