Definition and Overview

Also referred to as urodynamics or urodynamic testing, urodynamic studies refer to a series of tests that are conducted to assess the function and condition of the lower urinary tract.

The urinary system is composed of the kidneys, ureter, bladder, sphincter muscles, and the urethra. The lower tract is made up of the bladder and urethra.

The urinary system is responsible for draining the body’s metabolic by-products and excess water in the form of urine. First, the kidneys filter the body’s fluids to remove the impurities, toxins, and excess water. The wastes then move to the ureter and into the bladder. The bladder is a pouch-like organ that expands as it stores or collects urine. It also prevents the urine from returning to the kidneys through some of its muscles. The urine is kept there until it’s ready to be released to give way for another batch of urine. The walls of the bladder are composed of many nerves that signal the brain when it’s already full.

The bladder then relaxes to allow the urine to flow while the sphincter muscles help control how much urine is released. The urethra is where the urine passes through.

The urinary system between males and females are not different except for the length of the urethra, in which women have a shorter urethra than men.

Who Should Undergo and Expected Results

Patients who exhibit the symptoms below are candidates for urodynamic studies:

  • Incontinence or involuntary loss of bladder control
  • Changes in urination pattern
  • Burning sensation during urination
  • A feeling that the bladder is not completely emptied
  • Urination that is accompanied by pain in the lower back, fever, or discomfort
  • Changes in urine’s quality in terms of color, smell, and texture (e.g., cloudy)

How Does the Procedure Work?

The actual procedure depends on the test to be conducted:

  • Uroflowmetry – This is a test that evaluates the rate of flow and volume of the urine. Simply put, it measures how fast you expel urine. It uses specially designed equipment that measures the actual volume and speed of passing urine then feeds the data to a computer, which will then present the information in a graph form. The procedure is straightforward: in a private room, the patient urinates in a funnel or special toilet seat while the urine is being collected.

  • Cystometric test – This is a more comprehensive examination since it provides more crucial information such as bladder pressure. It involves inserting a catheter with a manometer into the bladder and performed under local anesthesia.

  • Electromyography – This is quite similar to the electrocardiograph of the heart, except that the sensors are attached to the skin of the urethra or the rectum. The purpose of the test is to determine and analyze the electrical activity of the lower urinary tract. It may be used to diagnose nerve damage on the bladder.

  • Postvoid Residual Measurement – This is an examination that determines how much urine the bladder stores after urinating. It can be accomplished using ultrasound or a catheter, which is inserted into the bladder.

Possible Risks and Complications

Some of the tests may be uncomfortable, especially if the patient is required to fill the bladder. This means that he needs to control any urge to urinate. The use of catheter may also cause some mild discomfort in the first few urine passes after the procedure. In some cases, a contrast medium may have to be swallowed. This is needed when the test uses an X-ray or a video, which captures the actual movements of the bladder when passing urine. Some people may be allergic to the contrast medium. Also, those with kidney issues may not be able to undertake the procedure since the body has to get rid of the dye completely.

Overall, however, the urodynamic studies are safe and are performed by licensed technicians and radiologist. The doctor doesn’t have to recommend all the mentioned tests to make a diagnosis. It all depends on the patient’s symptoms, medical records or history, or concern.


  • Nitti V. Urodynamic and videourodynamic evaluation of voiding dysfunction. In: Wein AJ, ed. Campbell-Walsh Urology. 10th ed. Philadelphia, PA: Saunders Elsevier; 2011:chap 62.

  • Lentz GM. Urogynecology: Physiology of micturition, voiding dysfunction, urinary incontinence, urinary tract infections and painful bladder syndrome. In: Lentz GM, Lobo RA, Gershenson DM, Katz VL, eds. Comprehensive Gynecology. 6th ed. Philadelphia, PA: Mosby Elsevier; 2012:chap 21.

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