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Urodynamics (Cystometry) Urology - Chestnut Unit

Posted Wednesday, 5 November 2025

Urodynamic studies

Urodynamics (cystometry) is an investigation of pressure and flow in the lower urinary tract; the bladder and urethra (tube through which you pass urine). The investigation allows specialist practitioners to assess the lower urinary tract function when filling and emptying.

Why do I need Urodynamics?

If you have a history of abnormal bladder function it may be due to one or more causes, these causes need to be identified to enable appropriate treatment. Without this information the specialist may not be able to offer any future surgical treatments.

Prior to the test

Important: If you feel you may have a urine infection on the day of your test you should contact the functional urology team on: 01752 430081. If you are prone to urine infections please ask your GP to check your urine 5 days prior to the appointment so that they can start antibiotic treatment before your test. We will check your urine on the day of your test, if there is any indication of urine infection it will be treated and the appointment will be rearranged.

If you are taking the following medication for your bladder/prostate please can you stop taking them one week prior to the appointment:

Darifenicin (Emselex)
Fesoterodine (Toviaz)
Oxbutynin (Lyrinol XL/Kentera)
Trospium chloride (Regurin)
Tamsulosin and Dutasteride (Combodart)
Tamsulosin Hydrochloride (Flomaxtra)
Alfuzosin Hydrochloride (Xatralg)
Solifenacin (Vesicare)
Tamsulosin and Solifenacin (Vesomni)
Mirabegron (Betgima)

Important: Doxazosin is taken for both prostate issues and high blood pressure. If you are taking it for high blood pressure reasons then this should not be stopped. If you have any concerns regarding medication please contact the Chestnut Unit, GP or your pharmacist for advice before stopping.

Video urodynamic only:

It maybe you are to have a video urodynamic test, if this is the case you will have fluoroscopy, which uses X-rays in combination with the pressure/flow assessment. This is needed to appropriately diagnose your condition. The amount of radiation via x-ray may vary dependant on the length of test. The consultant will advise you of the risk and benefits of the test as without this test it may not be possible to treat the underlying issue.

If you are a female it is important to note this procedure is not recommended in pregnancy and therefore this will need to be excluded prior to the test, please mention to the clinician if you have any concerns about pregnancy.

This procedure is currently performed in the Radiology department not the Chestnut Unit

What will happen?

The appointment and investigation will take approximately and hour.

You will need to arrive at the Chestnut Unit with a comfortably full bladder, the nurse will run through your previous urology history especially looking at life-style changes and medications. Some questions asked are important in making a diagnosis for your condition. If you feel you cannot answer any of these intimate questions, please let the clinician know. The clinician will review the bladder diary so please make sure this is fully completed and brought with you. The procedure will be explained and you will be asked for consent.

Once the pre-test checks are completed the nurse will ask you to change into a gown. The nurse will invite you to pass urine, as you would at home, into a special machine (flow meter) to measure your urinary flow. You will then be asked to lie down on the bed where the clinician will start to insert the catheters (small tubes) whilst examining both genital area and prostate (in men).

Various equipment used in Urology

Two catheters are used to assess the pressures in your bladder and abdomen. The clinician will firstly apply some local anaesthetic gel to the urethral catheter then pass it down the urethra into your bladder. During the test this catheter will slowly fill your bladder with fluid while measuring the bladder pressure. The second catheter will then be inserted into your rectum (back passage), this catheter will measure the abdominal pressure.

You will be asked to stand/sit on the edge of the bed or commode whilst your bladder fills, the clinician will ask you to describe your sensations in the bladder during this part of the test. The clinician may ask you to cough or perform certain straining manoeuvres to help provoke symptoms dependant on your history. Once your bladder has filled sufficiently the clinician will ask you to once more pass urine into the flow meter whilst the catheters remain in place.

Whilst your bladder is filling you may experience urgency, or leakage. This is expected for some patients so please try not to be alarmed, these symptoms are often what is being assessed.

Occasionally the test will need to be repeated. Following the test the catheters will be removed and a bladder scan may be performed to ensure the bladder has completely emptied. You will then be able to redress. Once you are dressed the clinician will explain the findings and will arrange for further clinic review or treatment.

Risks associated with the test

Discomfort: When placing the catheter into the bladder and rectum it may be uncomfortable. Local anaesthetic gel is used to lubricate and minimise the discomfort. Please inform the clinician if you are in pain.
Bleeding: There is a small chance that placing the catheters results in some bleeding from the bladder, prostate or urethra. This typically settles with good fluid intake. However, should it be persistent please contact the Chestnut Unit or your own GP or 111.
Urinary tract infection (UTI): When the catheter is inserted there is a small risk of introducing an infection (approximately 3 in 100 (3%)). We advise you to drink plenty of water following the test, if you think you have an infection after the test you'll need to contact your GP or 111. Occasionally the clinician may provide you with antibiotics to start taking on the day.