Urodynamics - NU Hospitals

What is the urinary tract?

The urinary tract is the body’s system for removing wastes and extra water. The urinary tract includes the kidneys, ureters, bladder, and urethra. The urine produced by the kidneys travels down two narrow tubes called the ureters. The urine is then stored in the bladder. The bladder becomes round shape when it is full and contracts as it empties. When the bladder empties, urine flows out of the body through the urethra.


What is the lower urinary tract and how does it work?

The lower urinary tract includes the bladder and urethra.


The lower urinary tract works by coordinat­ing the muscles of the bladder wall with the sphincters, which are valves that surround the urethra. The muscles of the blad­der wall relax as the bladder fills with urine. While passing urine the sphincter first opens and then the bladder contracts to generate pressure.


What is urodynamic testing?

Urodynamic testing is an advanced diagnostic procedure that assesses how well the bladder, sphincters, and urethra are storing and emptying urine. Most urodynamic tests focus on the bladder’s ability to hold urine and empty steadily and completely. Urodynamic tests can also show whether the bladder is having involuntary contractions that cause urine leakage.

When will you be advised urodyanmics testing?

Doctor’s may recommend uro­dynamic tests if symptoms suggest problems with the lower urinary tract. Essentially your doctor is trying to find out how efficiently and at what pressures does the bladder store and empty urine.

What do the urodynamic tests include?

Cystometric test


Postvoid residual measurement

Cystometric Test

A cystometric test measures how much urine the bladder can hold, how much pressure builds up inside the bladder as it stores urine, and how full it is when the urge to urinate begins and how you will empty the bladder completely.

How this test will be done?

A small tube is placed in the bladder to record pressure. Another tube may be placed in the rectum to record abdominal pressure. Once the bladder is emptied completely, the bladder is filled slowly with sterile 0.9% saline water. During this time, the person is asked to describe how the bladder feels and indicate when the need to urinate arises. When the urge to urinate occurs, the volume of water and the bladder pressure are recorded. The person may be asked to cough during this procedure to see if the bladder pressure changes. A cystometric test can also identify involuntary and inappropriate bladder contractions.

Note: These tests are performed under general anaethesia for very young children.


Electromyography uses special sensors to measure the electrical activity of the muscles and nerves in and around the bladder and the sphincters.

A sen­sor is placed on each side of the anus and one on the thigh. Electrical activity related to muscle is recorded on a machine.

Postvoid Residual Measurement

This urodynamic test measures the amount of urine left in the bladder after urination.

Is it painful or uncomfortable?

No, but you will feel a mild discomfort at time of tube insertion. Passing urine in a different enviroment (urodynamics room) can be embarrassing. However, adequate privacy will be provided during the test.

Is there any complication following this test?

After undergoing urodynamic tests, it is usual to feel mild discomfort for a few hours, especially when urinating. If you get any symptoms of infection including pain, chills, or fever; you should report to the hospital immediately.

When will I get my report?

The report will be immediately available and you can discuss it with your doctor.

Special instructions:

  • This test usually takes 1 hour
  • Do not drink fluids 3 hours before the test
  • You need not be fasting, unless you have to undergo the test under anesthesia
  • If stools are not cleared on the day of the test, you may be administered an enema to clear the stools
  • Women are to inform us beforehand if they are menstruating. The test will be postponed to a date after the menstrual cycle completes
  • If you are not a registered patient in our hospital, bring the reference letter and all investigation reports from your doctor
  • Certain investigations like recent urine culture, ultrasound and S.creatinine are mandatory for this test. You will need to have the reports prior to the test. You will be given antibiotic based on the sensitivity
  • You should report to the Urodynamics lab at least an hour before the test, on the date of appointment


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