Urodynamics: What, When, Why


The American Urological Association (AUA) interstitial cystitis (IC) treatment guidelines state that urodynamics should be considered as an aid to diagnosis only for complex cases of IC. These tests are not necessary for making the diagnosis in uncomplicated cases. There are no agreed-upon urodynamic diagnostic criteria for IC, inconsistent findings in IC patients—and, these tests can be very painful and uncomfortable for IC patients.

However, some cases of IC are complicated and may require urodynamic testing. For example, your doctor may do additional testing if there are signs and symptoms of other problems, such as incontinence, overactive bladder, blood or pus in the urine, endometriosis, or gastrointestinal conditions. For men, a misdiagnosis of chronic prostatitis/chronic pelvic pain syndrome (CP/CPPS) can also make it more challenging to diagnose IC.

Urodynamics isn’t one test but a group of tests to determine how your lower urinary tract is functioning. It gives physicians information on how much your bladder can hold, how much it can hold before you feel the need to urinate, how the bladder muscle is functioning, whether there might be any sphincter or pelvic floor dysfunction that hinders the outflow of urine, and whether you are retaining any urine in your bladder after it feels like you’re through urinating.

Urodynamic Testing & IC

Urodynamic tests can be very difficult for IC patients. The testing requires that the doctor insert a small catheter into the bladder; after the patient empties their bladder, the doctor, nurse, or technician may refill it to take special measurements. It usually takes about 30 minutes for the doctor to perform the various tests.

Because when you should undergo urodynamic tests if you have IC isn’t 100 percent clear, ask your doctor these questions to help you weigh the decision:

    • What question about my disease will the tests answer?
    • What changes in my treatment would we make based on the results?
    • How can urodynamics be made as comfortable as possible for me?
    • How much does the testing cost?

Jerry Blaivas, MD, believes that patients with IC who don’t respond to treatment should undergo videourodynamics. That’s because, when patients don’t get better, it’s important to look for other conditions that could be causing their symptoms, including overactivity of the bladder muscle, obstruction of or outpouching (diverticulum) in the urethra, or even bladder cancer. Urodynamics help diagnose bladder muscle overactivity, urethral obstruction, and urethral diverticula. Dr. Blaivas also finds that urodynamic tests offer additional useful information such as the relationship among bladder filling, bladder volume and the intensity of urge or pain and whether there is bladder muscle overactivity or the bladder is unable to expand. Urethral diverticulum or obstruction and overactive bladder (OAB) require different treatment from those prescribed for IC—without urodynamics, Dr. Blaivas says, the doctor wouldn’t know whether you had them.

Christopher Payne, MD, notes that no studies support use of invasive modes of urodynamics to help evaluate patients who may have IC. A study of nearly 400 women with IC-like symptoms showed that the older, strict diagnostic criteria that included urodynamics and cystoscopy with hydrodistention resulted in misdiagnosis in up to 60 percent of patients. After that study came out, Dr. Payne shifted his approach and now very selectively uses urodynamics. He believes that urologists can judge whether the bladder has lost its ability to expand clinically, without urodynamics and finds that bladder diaries are more useful and relevant than urodynamics for evaluating bladder capacity. However, because in his practice, men with IC have bladder neck obstruction more often than women, Dr. Payne may use routine uroflow and postvoid residual studies for better understanding the presentation of pelvic symptoms in some male patients.

Types of Urodynamic Tests

There many types of urodynamic tests which help evaluate how well your bladder fills and empties, the rate of your stream, and any abnormalities in bladder muscle contractions and leakage. An example of a noninvasive urodynamic test is listening to a patient void. For this test, the doctor or nurse asks you to urinate behind a curtain. While listening to your stream, the provider records observations about rate of flow. However, urodynamic testing usually involves more sophisticated medical procedures:

To help describe urodynamics, the ICA spoke with urogynecology nurse Tamara Dickinson, RN, of UT Southwestern Medical Center in Dallas, who performs these tests for the practice there. Tamara, in fact, started her urology career doing urodynamics, lectures to other nurses about it, and wrote the Society for Urologic Nurses and Associates’ patient fact sheet on the testing.


Uroflow Test or Uroflowmetry

This test measures how quickly you empty your bladder (urine speed and volume). Pressure uroflowmetry can help your doctor assess difficulty voiding, indicating weak bladder muscles or an obstruction. Weak bladder muscles and obstructed urine streams produce abnormal results.

Tamara shared that patients undergoing urodynamics may be given an antibiotic beforehand or after the procedures to avoid infection and need to arrive for testing with a full bladder. Then, they urinate using a special commode chair that has a funnel underneath with a transducer, that not only measures how much urine was in your bladder but also the force of the stream of urine. This part of urodynamics is called the “uroflow” test.

Post Void Residual Volume

For this part of the testing a catheter will be inserted into your bladder to drain out any remaining urine, showing whether you can empty your bladder completely. The doctor or nurse or technician will ask you to completely empty your bladder. It is normal when the bladder feels empty for a small amount of urine to remain in the bladder.

The post void residual volume test measures how much urine remains (usually one or two ounces). High volumes of urine may indicate urinary tract infection, incontinence, or other conditions. The doctor may also request that a lab check the urine sample for signs of infection.

Some doctors use an ultrasound to measure post void residual through sound waves; abnormal results are post void residuals of more than 200 mL.

Cystometry (Cystometrogram or Filling Cystometry)

The next part of the test is called a “cystometrogram” or “filling cystometry,” which measures the pressure in your bladder. To do this, after your bladder is empty, the nurse or technician must also insert another catheter with a small, suppository-like balloon on the end, which is a pressure sensor, into the vagina or rectum.

Inserting the catheters may be uncomfortable for some IC patients, although Tamara noted she isn’t familiar with IC patients’ experience because the physicians in her practice don’t routinely have IC or painful bladder syndrome (PBS) patients undergo these tests. Nevertheless, she said, how the nurse goes about inserting the catheters can make a difference in the patient’s comfort. Lubricant is used with both insertions, and Tamara also inserts the catheters very gently, having patients use relaxation techniques, such as deep breathing, as she advances the catheter. The catheters, she noted, are 7 French—about the size of a spaghetti noodle—and much smaller than the catheters usually used for bladder instillation.

The provider then fills your bladder with warm water and measures the levels of pressure in the bladder, rectum, urethra, and surrounding area. Because the bladders of IC patients typically hold less urine, the filling cystometry measurements are usually below the normal ranges. By asking patients to cough during this procedure, doctors can also check for stress incontinence.

The doctor or nurse may then ask you to empty your bladder and test the pressure levels in your bladder as you urinate and your urine’s rate of flow. In men, this test helps diagnosis bladder obstruction caused by an enlarged prostate.

Electromyography

During the cystometry, you may have some small electrodes placed on either side of the rectum that help record the electrical activity of muscles. By evaluating the patterns of impulses, your doctor can learn more about potential problems with nerve signaling between your bladder and urethra.

That is especially useful for detecting dysfunctional voiding patterns, (such as not relaxing the pelvic floor muscles to urinate), which could lead to unstable bladder contractions, resulting in frequency and urgency. Today, the electrodes are on small bandage-like adhesive patches. Needles or wires that go into tissue have greater potential to cause discomfort, but they are rarely used today, said Tamara. “A few people still use needle electrodes, but typically those are neurourologists working with patients who have impaired sensation, such as spinal cord injured patients,” she explained.

Videourodynamics

Special x-rays can also help your doctor better understand any abnormalities with the size and shape of your bladder and urinary tract.

The nurse or technician fills the bladder with sterile water, saline solution, or, sometimes, a contrast solution (a kind of dye solution that shows up on x-ray). When the contrast solution is used, the tests are referred to as “videourodynamics,” because the operator can watch the process on a monitor. That isn’t used in her urogynecology practice, said Tamara, who explained that videourodynamics are more commonly used for more complex patients, such as neurologically impaired patients (for example, patients with spinal cord injury or multiple sclerosis) or patients with a complicated history of incontinence.

As the bladder fills, the operator will record different pressure measurements, will find out how much the bladder holds, and will ask you to cough and push or bear down to check for leakage. She or he will also ask when you first feel your bladder filling, how it feels during filling, and when you feel like you need to void.

The filling process can be uncomfortable for IC patients. At this stage, said Tamara, “If I have a patient who’s got painful bladder symptoms, I’m not going to fill them as fast as I normally fill other patients. Filling more slowly helps avoid discomfort.” On the other hand, many urodynamic centers will want to fill your bladder at a standard rate so that the test results can be interpreted accurately when they are compared with results from patients without IC.

Sometimes, a further test is done, called a “urethral pressure profile,” which requires moving the catheter in and out. But, said Tamara, “That’s something that you’re more interested in if you’re looking at incontinence or prolapse. I wouldn’t usually do a urethral pressure profile if I had a patient who had a lot of pain and suspected IC.”

Voiding Pressure Study

The next test is called a “voiding pressure study” or “pressure flow study.” Once you feel that your bladder is full, you’ll be asked to urinate again using the special commode chair. The catheters are left in place for this. This test allows the operator to see how the bladder functions as it empties and whether anything is hindering the outflow of urine.

Tips for IC Patients Having Urodynamic Tests

Discomfort for a few hours after urodynamic tests, especially when you urinate, is normal even for people who do not have IC. To help keep your IC symptoms in check, plan ahead.

Before Urodynamic Testing

    • Ask the doctor about any changes in your treatment plan. Find out if you will be able to get a rescue solution or a stronger pain medicine to help manage the side effects of the procedures. Get the prescription filled before the procedure.
    • Review your personal IC flare strategies.
    • Ask your healthcare provider for any special instructions. Some urodynamic tests, require you to arrive with a full bladder and others an empty one.
    • Find a family member or friend who can drive you and bring you home.
    • Let your healthcare team know how you are feeling that day. When you arrive, let the nurse and doctor know if you are having IC pain or any other discomfort.
    • Bring your pain and voiding diaries with you. Discuss your symptoms and ask about special precautions to reduce pain and discomfort associated with the procedure such as using a very small catheter.

After Urodynamic Testing

    • Put your IC flare remedies into action.
    • Take pain medicine, as needed, to control added discomfort and pelvic pain.
    • Sip water, aim for eight ounces each half-hour for two hours.
    • Ask your doctor if warm baths are okay. If not, try relieving discomfort by placing a warm, damp washcloth over the urethral opening.
    • Follow doctor’s orders regarding any changes to your IC treatment plan.
    • Call the doctor’s office if you experience higher levels of pain, chills or fever.

Posted March 25, 2011