Care at NUH

Services for Urodynamic Study

What is a urodynamic study or video-urodynamic study?
A urodynamic study  (UDS) is performed to gather more information about the urination process and assess the functionality of the bladder muscles. The goal is to replicate the urinary symptoms during the study. 

A UDS includes cystometry and uroflowmetry in a single session. Video urodynamic study (VUDS) involves the use of fluoroscopy to observe the whole urination cycle during the test. The traces generated by UDS/VUDS can be visualised on the computer screen, facilitating the interpretation of study results. 

These studies are performed to better understand a patient’s condition, enabling the doctor to provide the right treatment and advice. 
Indications for UDS/VUDS
  • Mixed incontinence
  • Overactive bladder (OAB)
  • Failed medical therapy for OAB/benign prostatic hyperplasia
  • Suspected bladder outlet obstruction
  • Neurological conditions with urinary symptoms
  • Neurological conditions with involvement of upper urinary tracts
  • Planning for specific surgeries which require assessment of the bladder or urethra
  • Previous surgery with persistent urinary symptoms
  • Incontinence after surgery (eg: Transurethral resection of prostate, radical prostatectomy, mid-urethral slings)
  • Voiding dysfunction
Before the procedure
Before undergoing the urodynamic study, it is advisable to provide a urine sample in advance to confirm the absence of infection. Some medications may need to be temporarily discontinued before the test, and it is recommended to consult with your doctor regarding this. The testing process takes about 30-60 minutes, and VUDS involves small doses of radiation. 

If you have an ongoing infection, antibiotics treatment is necessary before proceeding with UDS. If the urinary test is not conducted at the hospital, please bring the results to your appointment. 

Please complete the bladder diary before the study, as it contains essential information for the urologist. Do arrive 30 minutes before the scheduled study rest assured that you can have a meal before the examination. 
The procedure


The patient will be accompanied to a quiet room with a nurse and attending urologist. 

In a lying position, a small catheter is inserted in the urethra with the application of a local anaesthetic gel. Another catheter will be placed in the rectum. Both catheters will be securely taped to the body. 

Both catheters measure the pressure in the bladder and abdomen, with the traces being reflected on the computer screen. 

Sensing electrodes may be placed near the rectum to monitor the activity of the pelvic muscles. 

The patient may be asked to stand up or sit down during the study, and adjustments to the position may be requested as needed.  

Using the catheter, the bladder will be filled with a sterile saline fluid and the patient will be asked to cough or bear down to test the bladder reaction throughout the test. 

The doctor checks for any urine leakage and assess if these is any abnormal urge to urinate. 

One the bladder is completely full, the patient will be asked to empty it while the pressure is being recorded, facilitated by the urethral catheter. 


The urinary flow will be recorded and the patient may be asked to perform certain actions to assist in the flow. 

The residual urine volume will be measured. 

At the end of the cystometry test, the catheters and sensors are removed. 

Risks and Follow-Up


UDS/VUDS is generally a safe and well-tolerated study. 

Sudden high blood pressure (autonomic dysreflexia)- Rare 

Some patients with neurological conditions (eg spinal cord injury) have a risk of sudden high blood pressure (autonomic dysreflexia) during UDS. It is a sudden and exaggerated automatic response to various stimuli in patients with spinal cord injury or spinal dysfunction. Sudden high blood pressure can be life-threatening if not properly managed. We will need to closely monitor the blood pressure of these patients during the tests. Please let your urologist know if you have any spinal cord injuries or concerns.   


Right after the tests are done, your doctor will discuss the results with you, and any further treatment you may need.

Drink plenty of liquids after the tests to reduce discomfort while urinating.

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