Urodynamic Testing

Urodynamics in men with an enlarged prostate: why, what and what to expect?

What are urodynamics?

This is a one-hour outpatient diagnostic test to help understand why urinary symptoms are present and to help predict the outcome of treatment. The tests aims to determine the activity of the bladder whilst it is filling with fluid, and the pressure and speed at which urine is passed.

To do this, a very narrow tube has to be passed into the bladder through the urethra. Sometimes, it is combined with x-rays and is known as 'videourodynamics'. A gel with local anaesthesia may be used, but not general anaesthesia. Pressures are measured in the rectum (a.k.a. back passage) at the same time through another narrow tube.

Why am I having this test?

The test can determine the cause of urinary symptoms such as:

  • slow flow, stopping and starting, and the need to dribble to finish passing urine
  • increased frequency of passing urine during the day and night
  • urine leakage (incontinence)

It can also help predict whether drugs or surgery are likely to have a good result for:

  • urinary symptoms in men due to obstruction of the bladder by the prostate (BPH) or other cause
  • overactivity of the bladder (also known as detrusor instability or detrusor overactivity)

What should I do before this test?

If you are taking drugs for your prostate or bladder, you should probably stop these a week before having the test. Check first with the nurses or doctors. These include:

  • solifenacin (Vesicare)
  • tolterodine (Detrusitol)
  • oxybutynin (Kentera patches, Cystrin, Ditropan, Lyrinel)
  • trospium (Regurin)
  • propiverine (Detrunorm)
  • tamsulosin (Flomax)
  • terazosin (Hytrin)
  • indoramin (Doralese)

It is not necessary to fast the night before or take laxatives. As long as a urine test to test for infection is normal, the study is very safe and can be performed with minimal discomfort. It is important to arrive with an almost full bladder since it may be necessary to do a urinary flow test before the formal urodynamic test. Usually, a nurse will be in the room during the study. Occasionally, a radiographer or doctor may be there also.

What will happen during the test?

You will need to undress and put on a gown. Local anaesthetic jelly will be placed in the urethra. A narrow tube (catheter) will be placed by a doctor or nurse through the urethra into the urinary bladder. In addition, another narrow tube will be placed in the rectum, which improves the accuracy of the test. The study can be performed whilst standing or sitting. A computer will record all of the measurements and a “tracing” will be generated.

Your doctor may be present during the critical parts of the study. He will analyse and interpret the study based on the tracings and x-rays if these are taken.

What happens after the test?

Half an hour after the test, you will be able to go home. You may experience some burning when passing urine for a few days and this is normal. There may be some blood in the urine, but as long as large clots are not formed, the bleeding will settle if you drink plenty of fluid. You can resume regular diet, medications, and normal activity levels after you leave. Often, antibiotics are prescribed for a few days afterwards. Your results will be discussed in outpatients.

For more information, download the following file:

urodynamics patient information