Urodynamic tests

Urodynamic tests assess the dynamic function of the lower urinary tract. The tests assess 3 functions;

• The ability of the bladder to stretch without alarming you to feel the need to go the toilet. A normal bladder should accommodate almost half a litre and give enough warning before you need to go to the toilet. With an overactive bladder, one will need to go to the toilet frequently and passes small volumes.
• Ability to hold urine when coughing or sneezing. The area between the bladder and urethra should be strong enough to prevent leakage of urine. A weak bladder neck does not hold urine and may leak small drops on coughing and sneezing. This is known as stress incontinence.
• Ability to pass urine. A normal bladder empties promptly and completely. People with voiding dysfunction may take a few moments to start and / or a long time to empty their bladder. They may have to go back to the toilet soon after finishing.

The function of the bladder is rather complex and problems do not often present in the classic way. Symptoms do not match the expected underlying problems outlined above and may co exist together.

Urodynamics will help establish the three aspects of bladder function more accurately.

You might be asked to complete a bladder diary (frequency volume chart) for three days, if you have not already done so. This provides an idea about the nature and amount of your fluid intake as well as how much and how often do you pass urine. This enables understanding your bladder function.

If you are taking tablets to improve your bladder function, you need to stop these medications for 2 weeks prior to the test. On the day of the test, it is good to wear clothes that are easy to remove, as you will be asked to remove clothes from your bottom half and wear a gown.

Try to arrive with a comfortably full, or at least half full, bladder, as you will be asked to pass urine at the start of the test.

If you are known to have recurrent urinary tract infection, you will be asked to have a urine test a week or so before the appointment. You might be provided with an antibiotic prescription prior to use prior to the test.

On arrival, you will be taken to a private area. You will be asked to remove the clothes on your bottom half and will be given a robe to wear. You will be asked to pass urine in a commode (special toilet) that will measure the rate and volume of you passing urine.

After that, you might be examined to assess if you have prolapse, if this has not been done before. The area around the urethra is cleaned and a catheter is passed into your bladder, to fill it and record pressure changes. Another catheter will be passed either through the vagina or rectum to get the pressure inside your abdomen. This will be deducted from the pressure inside your bladder to the get the pressure caused by the bladder itself.

The test can be carried out in the sitting, semi sitting, lying down or standing position.

The rate of bladder filling will be varied to test your bladder. You will be asked to cough from time to time, to ensure the catheters are in place. You will be asked to perform a number of manoeuvres, such as bearing down, washing your hands in water and bouncing your heels, to assess your bladder function.

At the end, you will be asked to pass urine again in the commode, this time with catheters in place.

A scan might be performed to measure how much urine is left in the bladder. If this is significant, it might be emptied by a catheter.

In some instances, the test will be performed under x ray to see the shape and mobility of the bladder. This is called video urodynamics.

In others, the pressure in the urethra is measured using a special catheter. This is called urethral pressure profilometry.

In a few, the pelvic floor muscle will be assessed using a special needle. This is called electromyography.

At the end the doctor will talk to you about the test result and how they intend to manage your symptoms.

Occasionally the test may conflict with your symptoms. This may necessitate more tests, such as the pad test. In this test, you will be given a specified amount of water to drink. You will then be asked to perform specific tasks, such as walking, going up the stairs and coughing, while wearing a pre weighed pad, which will be re weighed at the end.

A few patients may develop a urinary tract infection. You are advised to drink more water than you normally do after the test and for 2 to 3 days afterwards, to flush any bacteria. If you are at risk of infection, for example if you are diabetic, you might be given prophylactic antibiotics.

You should contact your doctor or the hospital if you notice increased temperature, frequency of passing urine, smelling or cloudy urine or if you feel generally unwell.

Your Pelvic Floor

National Institute for Health and Care Excellence: urinary continence and prolapse in women

Urology Care Foundation