When overactive bladder (OAB) is a possibility, several diagnostic tests—ranging from basic urinalysis to specialized bladder-function tests—are available to verify OAB or identify other conditions that could be causing the symptoms.
Physical Exam and Basic Tests
Your primary care doctor will ask you questions and perform a physical exam that might include one or more of the following tests.
Pelvic or Prostate Exam
A female pelvic exam is done to examine any vaginal abnormalities and to see if the pelvic muscles needed for urination are good condition. This also checks to see if the muscle attachment in the vaginal region is strong enough to perform its functions. Weak pelvic muscles can lead to urge incontinence as a symptom of OAB or stress incontinence, which is usually independent from OAB.
In men, a prostate exam will determine whether an enlarged prostate is causing OAB symptoms.
A neurological exam is preformed to test the reflexes and sensory response. Because OAB can be caused by a neurological condition, the motor reflexes of muscles are checked.
Cough Stress Test
This test will rule out the possibility of stress incontinence, which is different than OAB. It is performed by drinking fluids, relaxing afterwards, and then coughing to see if stress or physical exertion causes urinary incontinence. This can also help determine if the bladder fills and empties like it should.
A urine specimen is checked for abnormalities. The presence of blood or glucose may point to conditions that have symptoms similar to those of OAB. For example, the presence of bacteria may indicate a urinary tract infection, which can cause feelings of urgency.
These tests are designed to measure the bladder’s ability to empty properly. They can also determine whether the bladder is contracting involuntarily, which might cause symptoms of urgency, frequency, and incontinence. An antibiotic may be prescribed before or after the tests to prevent infection.
During this test, the patient voids into a uroflowmeter, which measures the volume and speed of urination. The peak flow rate will be displayed on a chart and reveal whether the bladder muscle is weak or if there is an obstruction such as a bladder stone.
Postvoid Residual Volume (PRV)
The PRV test measures urine that remains in the bladder after urination. If the bladder does not empty completely with urination, symptoms similar to those of OAB may occur. Sometimes a catheter is used to drain the remaining urine in the bladder for measurement.
A test called a cystometrogram measures how much urine your bladder can hold. It also measures the amount of pressure in the bladder as it fills with urine. A catheter is used to fill the bladder with saline and measure pressure. This test will show how full your bladder is when you feel the urge to urinate and can detect involuntary contractions. And finally, after your bladder is full, you will empty it, and the catheter will measure the pressure needed for you to urinate. This is called a pressure-flow study and can identify the presence of an obstruction.
Using sensors placed on the skin near the urethra, an electromyogram measures the nerve impulses and muscle activity in the bladder and urethral sphincter. This test will reveal whether or not the nerve impulses being sent to the bladder are normal.
A thin instrument known as a cystoscope is inserted into the bladder through the urethra. The cystoscope allows the doctor to see the inside of the urethra and bladder to check for abnormalities as well as find out how much urine the bladder is holding.