Complex or Advanced Diagnostic Tests
In some patients the simple, basic tests for incontinence do not provide enough information to make an accurate diagnosis and be able to plan appropriate therapy. These patients may have complex histories with lots of medical problems, or may have had previous treatments or surgery that failed. In these patients, more complex testing is indicated. Many doctors, that specialize in incontinence problems, may have or have access to special “multichannel urodynamic” equipment. With this special equipment and an appropriate understanding of a particular patient’s problem, even the most complex problems determined. Some of the typical tests done with this equipment are:
- Uroflow Testing
- Multichannel Cystometry
- Voiding Pressure-Flow Studies
- Urethral Pressure Profiles
Each one of these tests provides different and valuable information about a how a patient’s bladder is working.
A uroflow test is usually done first. The patient is asked to simply urinate in a special toilet that measures the speed and volume of urine produced. Afterward, a small catheter is placed in the bladder to drain out the remaining urine, and this residual urine volume (PVR) is recorded. This information may help the doctor figure out the way in which a patient voids. Most people void in a continuous fashion, once they start, until the bladder is empty. Some women have to strain and push on the bladder in order to empty and will void in a very intermittent fashion, and have a weak stream.
Multichannel cystometry is done by placing a small catheter with a special device on the end that can measure pressure in the bladder. A second catheter is placed in the vagina or rectum. The study is usually done in the standing or sitting position. Sterile water or saline is slowly pumped into the bladder. As the bladder is filling, the woman is asked to do activities that typically would make her leak (i.e., walk, stand, jump, cough, laugh, etc.). The catheters are hooked up to a computer that records and plots the measured pressures and can subtract these measured pressures to produce a “true” bladder pressure. At the same time, small electrodes are place on the skin, or preferably in the muscle fibers of the external sphincter muscle, and an “EMG” measurement is obtained. An EMG of a muscle is simply a measure of the electrical activity of that muscle similar to an “EKG” of the heart, with which we are all familiar. An EMG of a muscle gives an indication as to how well that muscle is working the greater the signal, the harder the muscle is contracting. By using all these measurements you can usually identify the cause of a woman’s incontinence if they leak during the study. If the patient does not leak the results are more difficult to interpret, but are still very useful.
Voiding pressure flow studies are usually next done. With the bladder filled and the catheters and electrodes in place from the previous study, the patient is asked to again void on the special toilet. This time, as she voids, not only is the speed and volume of the urine produced recorded, but the pressure in the bladder and the activity of the external urethral sphincter muscle is recorded. With this test the doctor can actually measure the strength of the bladder muscle and also check to see if the urethral sphincter muscle is relaxing the way it should.
Finally, urethral pressure profiles are done at the same time. The catheter in the bladder from the previous study is slowly pulled down into the urethra (the tube from the bladder to the outside) and the pressure in the urethra can be recorded. Remember from our previous discussion that we said that the pressure in the urethra was an important part of the way the system works to keep the urine in the bladder. People that have a damaged urethra or intrinsic sphincter deficiency, either from previous surgery, injury to the nerves in the pelvis or multiple dilatations can have very low or none existent pressure readings. These women can have a severe form of incontinence and leak all the time, especially when standing.