Lower urinary tract symptoms (LUTS) are storage, voiding and postmicturition symptoms affecting the lower urinary tract. LUTS can significantly reduce men’s quality of life, and may point to serious pathology of the urogenital tract.

What is Urodynamics?

Urodynamics are a means of evaluating the pressure-flow relationship between the bladder and the urethra for the purpose of defining the functional status of the lower urinary tract. The ultimate goal of urodynamics is to aid in the correct diagnosis of lower urinary tract dusfunction based upon its pathophysiology. Urodynamic studies should assess both the filling and storage phase, as well as the voiding phase of bladder and urethral function. In addition, provocative tests can be added to try to recreate symptoms and assess pertinent characteristics of urinary leakage.

Urodynamic tests include:

 uroflowmetry

 postvoid residual measurement

 cystometric test

 leak point pressure measurement

 pressure flow study

 electromyography

 video urodynamic tests

Uroflowmetry

Uroflowmetry is the measurement of urine speed and volume. Special equipment automatically measures the amount of urine and the flow rate—how fast the urine comes out. Uroflowmetry equipment includes a device for catching and measuring urine and a computer to record the data. During a uroflowmetry test, the person urinates privately into a special toilet or funnel that has a container for collecting the urine and a scale. The equipment creates a graph that shows changes in flow rate from second to second so the health care provider can see when the flow rate is the highest and how many seconds it takes to get there. Results of this test will be abnormal if the bladder muscles are weak or urine flow is blocked. Another approach to measuring flow rate is to record the time it takes to urinate into a special container that accurately measures the volume of urine. Uroflowmetry measurements are performed in a health care provider’s office; no anesthesia is needed.

Postvoid Residual Measurement

This urodynamic test measures the amount of urine left in the bladder after urination. The remaining urine is called the postvoid residual. Postvoid residual can be measured with ultrasound equipment that uses harmless sound waves to create a picture of the bladder. Bladder ultrasounds are performed in a health care provider’s office, radiology center, or hospital by a specially trained technician and interpreted by a doctor, usually a radiologist. Anesthesia is not needed. Postvoid residual can also be measured using a catheter—a thin flexible tube. A health care provider inserts the catheter through the urethra up into the bladder to remove and measure the amount of remaining urine. A postvoid residual of 100 milliliters or more is a sign that the bladder is not emptying completely. Catheter measurements are performed in a health care provider’s office, clinic, or hospital with local anesthesia.

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. A catheter is used to empty the bladder completely. Then a special, smaller catheter is placed in the bladder. This catheter has a pressure-measuring device called a manometer. Another catheter may be placed in the rectum to record pressure there.

Once the bladder is emptied completely, the bladder is filled slowly with warm 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 or strain during this procedure to see if the bladder pressure changes. A cystometric test can also identify involuntary bladder contractions. Cystometric tests are performed in a health care provider’s office, clinic, or hospital with local anesthesia.

Leak Point Pressure Measurement

This urodynamic test measures pressure at the point of leakage during a cystometric test. While the bladder is being filled for the cystometric test, it may suddenly contract and squeeze some water out without warning. The manometer measures the pressure inside the bladder when this leakage occurs. This reading may provide information about the kind of bladder problem that exists. The person may be asked to apply abdominal pressure to the bladder by coughing, shifting position, or trying to exhale while holding the nose and mouth. These actions help the health care provider evaluate the sphincters.

Pressure Flow Study

A pressure flow study measures the bladder pressure required to urinate and the flow rate a given pressure generates. After the cystometric test, the person empties the bladder, during which time a manometer is used to measure bladder pressure and flow rate. This pressure flow study helps identify bladder outlet blockage that men may experience with prostate enlargement. Bladder outlet blockage is less common in women but can occur with a cystocele or, rarely, after a surgical procedure for urinary incontinence. Pressure flow studies are performed in a health care provider’s office, clinic, or hospital with local anesthesia.

Electromyography

Electromyography uses special sensors to measure the electrical activity of the muscles and nerves in and around the bladder and the sphincters. If the health care provider thinks the urinary problem is related to nerve or muscle damage, the person may be given an electromyography. The sensors are placed on the skin near the urethra and rectum or on a urethral or rectal catheter. Muscle and nerve activity is recorded on a machine. The patterns of the nerve impulses show whether the messages sent to the bladder and sphincters are coordinated correctly. Electromyography is performed by a specially trained technician in a health care provider’s office, outpatient clinic, or hospital. Anesthesia is not needed if sensors are placed on the skin. Local anesthesia is needed if sensors are placed on a urethral or rectal catheter.

Video Urodynamic Tests

Video urodynamic tests take pictures and videos of the bladder during filling and emptying. The imaging equipment may use x-rays or ultrasound. If x-ray equipment is used, the bladder will be filled with a special fluid, called contrast medium, that shows up on x-rays. X-rays are performed by an x-ray technician in a health care provider’s office, outpatient facility, or hospital; anesthesia is not needed. If ultrasound equipment is used, the bladder is filled with warm water and harmless sound waves are used to create a picture of the bladder. The pictures and videos show the size and shape of the bladder and help the health care provider understand the problem. Bladder ultrasounds are performed in a health care provider’s office, radiology center, or hospital by a specially trained technician and interpreted by a doctor, usually a radiologist. Although anesthesia is not needed for the ultrasound, local anesthesia is needed to insert the catheter to fill the bladder.