Urodynamics is the investigation of functional disorders of the lower urinary tract, i.e. the bladder and the urethra. Symptoms reported by the patient are often an unreliable guide to the underlying dysfunction of the lower urinary tract. The purpose of urodynamics is to provide objective confirmation of the pathology that a patient's symptoms would suggest.
Urodynamics is a study that assesses how the bladder and urethra are performing their job of storing and releasing urine. Urodynamic tests help your doctor or nurse see how well your bladder and sphincter muscles work and can help explain symptoms such as
incontinence
frequent urination
sudden, strong urges to urinate
problems starting a urine stream
painful urination
problems emptying your bladder completely
recurrent urinary tract infections
These tests may be as simple as urinating behind a curtain while a doctor or nurse listens or more complicated, involving imaging equipment that films urination and pressure monitors that record the pressures of the bladder and urethra.
Seeing Your Doctor
The first step in solving a urinary problem is to talk with your doctor or nurse. He or she should ask you about your general medical history, including any major illnesses or surgeries. You should talk about the medicines you take, both prescription and nonprescription, because they might be part of the problem. You should talk about how much fluid you drink a day and whether you use alcohol or caffeine. Give as many details as you can about the problem and when it started. The doctor or nurse may ask you to keep a voiding diary, which is a record of fluid intake and trips to the bathroom, plus any episodes of leakage.
If leakage is the problem, the doctor or nurse may ask you to do a pad test. This test is a simple way to measure how much urine leaks out. You will be given a number of absorbent pads and plastic bags of a standard weight. You will be told to wear the pad for 1 or 2 hours while in the clinic or to wear a series of pads at home during a specific period of time. The pads are collected and sealed in a plastic bag. Your health care team will then weigh the bags to see how much urine has been caught in the pad. A simpler but less precise method is to change pads as often as you need to and keep track of how many pads you use in a day.
A physical exam will also be performed to rule out other causes of urinary problems. This exam usually includes an assessment of the nerves in the lower part of your body. It will also include a pelvic exam in women to assess the pelvic muscles and the other pelvic organs. In men, a rectal exam is given to assess the prostate. Your doctor will also want to check your urine for evidence of infection or blood.
Preparing for the Test
If the doctor or nurse recommends bladder testing, usually no special preparations are needed, but make sure you understand any instructions you do receive. Depending on the test, you may be asked to come with a full bladder or an empty one. Also, ask whether you should change your diet or skip your regular medicines and for how long.
Most urodynamic testing focuses on the bladder’s ability to empty steadily and completely. It can also show whether the bladder is having abnormal contractions that cause leakage. Your doctor will want to know whether you have difficulty starting a urine stream, how hard you have to strain to maintain it, whether the stream is interrupted, and whether any urine is left in your bladder when you are done. The remaining urine is called the postvoid residual. Urodynamic tests can range from simple observation to precise measurement using sophisticated instruments.
Free uroflowmetry measures how fast the patient can empty his/her bladder.
Multichannel cystometry measures the pressure in the rectum and in the bladder, using two pressure catheters, to deduce the presence of contractions of the bladder wall, during bladder filling, or during other provocative manouevres. The strength of the urethra can also be tested during this phase, using a cough or Valsalva manouvre, to confirm genuine stress incontinence.
Pressure uroflowmetry again measures the rate of voiding, but with simultaneous assessment of bladder and rectal pressures. It helps demonstrate the reasons for difficulty in voiding, for example bladder muscle weakness or obstruction of the bladder outflow.
These common tests may be augmented by EMG measurement of electrical activity in the bladder neck, urethral pressure profilometry, assessing the "tightness" along the length of the urethra, and fluoroscopy (moving video x-rays) of the bladder and bladder neck during voiding.
The tests are most often arranged for men with enlarged prostate glands, and for women with incontinence that has either failed conservative treatment or requires surgery.
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