Bladder function tests, also called urodynamics testing, help to determine the functioning of the urinary bladder. The tests focus on the ability of the bladder to hold urine and release it steadily. Bladder function tests may be suggested if a patient shows symptoms such as urine leakage, painful urination, sudden urges to urinate, or problems in completely emptying the bladder.
Bladder function tests range from simple observational to more complex tests depending on the symptoms.
Bladder function tests and familial amyloid polyneuropathy
Familial amyloid polyneuropathy (FAP) is an autosomal dominant genetic disease caused by mutations in the TTR gene. The TTR gene provides the instructions to make a protein called transthyretin (TTR) in the liver, which is important for the transport of vitamin A and thyroxine in the body.
More than 100 mutations have been identified in the TTR gene which can result in the improper functioning of the TTR protein and accumulation of abnormal protein deposits called amyloids. These amyloids tend to get deposited in various parts of the body, primarily in the nervous system and heart. FAP affects the functioning of the autonomic nervous system (autonomic neuropathy), which often results in improper bladder function, a condition known as neurogenic bladder.
Various bladder function tests can assess the extent of bladder dysfunction due to autonomic neuropathy.
Types of bladder function tests
There are several bladder function or urodynamic tests that are available. A clinician can prescribe one or more of these tests depending on the symptoms observed.
Uroflowmetry
Uroflowmetry measures the speed and volume of urine. Patients are asked to urinate privately in a special toilet that is equipped with a scale. The instrument records the flow of urine per second on a graph which helps the urologist to determine whether or not the flow is abnormal. An abnormal flow indicates that bladder muscles are affected or urine flow is blocked. No anesthesia is needed for this test.
Post-void residual measurement
This test helps determine the volume of urine left in the bladder (post-void residual) after urination. This can be measured using ultrasound without the need for anesthesia.
In another method, a urologist inserts a catheter into the bladder via the urethral opening to extract the residual urine. If the volume of urine in the bladder is 100 ml or more, it indicates an abnormality in bladder function. This procedure requires local anesthesia.
Cystometric test
This test measures the amount of urine the bladder can hold, the pressure inside the bladder, and the state of the bladder at the onset of the urge to urinate. To perform this test, the urologist inserts a catheter to drain out the bladder. Then another catheter with a pressure-measuring device, called a manometer, is inserted to record the pressure inside the bladder.
The bladder is filled with warm water, and the patient is asked to inform the health professional when they have an urge to urinate. This test can also indicate whether there are any involuntary bladder contractions. A local anesthesia is required for this procedure.
Leak point pressure measurement
This test can help assess the kind of bladder problem that causes urine leakage. It can be done while filling the bladder during a cystometric test, and can provide the bladder pressure reading at the time of urine leakage.
Electromyography
Electromyography can be used to detect electrical activity in the bladder muscles and nerves. The pattern of the electrical signals indicates whether there is any muscle or nerve damage. Electrodes are generally placed on the skin and require no anesthesia, but local anesthesia might be necessary if the electrodes are placed in a catheter and inserted into the urethra or rectum.
Video urodynamic tests
Video urodynamic tests use either X-rays or ultrasound to record pictures and video of the bladder during filling and emptying. If X-rays are used, the bladder is filled with a contrast fluid so that it lights up on the X-ray film. If ultrasound is used, the bladder is filled with warm water using a catheter, and sound waves are used to create a picture of the bladder. This helps the clinician to better understand the workings of a patient’s urinary bladder. Anesthesia is not required for either procedure but local anesthesia might be administered while inserting the catheter into the urethra.
Other information
For a few hours after undergoing bladder function tests, a patient might experience slight discomfort while urinating. Drinking a glass of water every 30 minutes should help relieve the discomfort. Holding a warm, damp washcloth over the urethral opening can also help.
Antibiotics are rarely needed and only prescribed if the urologist feels there is a risk of infection.
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