What are urodynamic tests?

Urodynamic tests help doctors assess the function of your bladder and are often done to investigate urinary incontinence. During the tests, your bladder is filled and then emptied while pressure readings are taken from your bladder and your tummy (abdomen). The idea is to replicate your symptoms, then examine them and determine their cause.

What are urodynamic tests used for?

Urodynamic tests are used to help diagnose:

  • Stress urinary incontinence-leakage of urine with activity- eg sneezing, heavy lifting, exercise.

  • Urge urinary incontinence- uncontrolled urine leakage at unforeseen times eg- turning on tap, key in the door, standing up from chair.

  • Mixed urinary incontinence (stress and urge urinary incontinence)

  • Neurogenic or hypotonic bladder- the loss of bladder sensation and loss of muscle contracture.

 Urodynamic tests are particularly important if surgery is being considered for the problem, to ensure the correct operation is performed.

Understanding urine and the bladder

The kidneys make urine all the time and a trickle of urine is constantly passing to the bladder down the tubes from the kidneys to the bladder (the ureters). You make different amounts of urine depending on how much you drink, eat and sweat. The bladder is a large muscle and stores the urine expanding (like a balloon) as it fills up with urine. The outlet for urine (the urethra) is normally kept closed by a sphincter and is helped by the pelvic floor muscles (these muscles sling from your pubic bone to the coccyx wrapping around the urethra, vagina & rectum. When a certain amount of urine is in the bladder you become aware that the bladder is getting full by an "urge". When you empty your bladder, the bladder muscle squeezes "contracts" and the urethral sphincter and pelvic floor muscles relax to allow the passage of urine.

Complex nerve messages are sent between the brain, the bladder and the pelvic floor muscles. These tell you how full your bladder is and which muscles are right to contract or relax at the correct time.

How do urodynamic tests work?

The first part of the tests checks how much urine leaves your bladder over a certain time "flow rate". A special toilet records the flow of your urine. The second part of the tests is called filling cystometry and require thin catheters inserted into your bladder and your back passage (rectum). These can measure the pressure in your bladder and tummy (abdomen) as your bladder fills with fluid and these measurements are used by the doctors to compare the different pressure readings.If urine leaks with no change in pressure in your bladder muscle, you may have stress incontinence. Leaking is brought on (provoked) by an increase in pressure inside your abdomen - for example, when coughing.

If involuntary bladder muscle activity causes an increase of pressure in your bladder and leads to leaking, you may have urge incontinence.

What happens during urodynamic testing?

Testing is done in our rooms we do not use xray during this test.

For the first part of the test, you will need to empty your bladder into a special toilet called a flowmeter which measures how much urine you pass and the strentgh of the flow of the urine.An ultrasound will then be doneto see how empty your bladder is. This is why you need to come to the test with a full bladder.

The next part of the test measures the way your bladder works as it fills up. Two very thin tubes (catheters) are put into your bladder, by inserting them into the tube from your bladder that passes out urine (your urethra). You may find this a little uncomfortable. One is to fill up your bladder and the other is to measure the pressure in your bladder. Another catheter is put into your back passage (rectum). This allows the pressure inside your bladder to be compared with the pressure outside your bladder.

Once the catheters are in the correct position, fluid runs into your bladder at a controlled rate. This slowly fills your bladder whilst recordings are made. The doctor or nurse performing the test will ask you questions - for example, how your bladder feels and when it feels full.

Once your bladder is full, the bed will move and stand you upright. You may be asked to cough and some X-rays of your bladder are taken.

If you leak urine when you cough, do not to feel embarrassed as if you leak at home when you cough, it is best for the doctor to see you leak during the test. It is important to remember that this test is for your doctor to be able to provide you with the best treatment options depending on your results.

What should I do to prepare for a urodynamic test?

If you are taking any medication for your bladder then it is likely that you will be asked to stop this for a week before this test. Arrive with a full bladder but you should not push fluids prior.The test usually takes around 1 hour.

What can I expect after a urodynamic test?

After the tests some stinging or burning sensation when they pass urine is common. It is advised to drink plenty of fluids and these symptoms should quickly settle. If discomfort lasts more than 24 hours, you should take a sample of your urine to your GP for testing because it may be a sign of infection.Some people find a small amount of blood in their urine when they go to the toilet. This is common and should settle quickly.There is a small possibility that you may develop a urinary tract infection and will require antibiotics especially if you have history of urine infections. If you have any symptoms that are a concern following urodynamics speak to your doctor.​

Are there any side-effects or complications from a urodynamic test?

Most people have urodynamic tests without experiencing any problems. As mentioned above, there is a small chance of developing a urinary tract infection. Contact your doctor if you develop any of the following symptoms:

  • A stronger than usual urge to pass urine.

  • Your urine smells, is cloudy or has blood in it.

  • You want to pass urine more often during the day and night.

  • A burning or stinging sensation when you pass urine and feel that you are only passing small amounts at a time.

  • Lower backache or pain in your kidneys.

  • If you feel hot and develop a high temperature.