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Female incontinence: the role of urodynamic testing

Issue: March 2010

By: J. Linn Daudel, M.D.

Urinary incontinence is a common disorder in the U.S., affecting up to 25 million people. Women disproportionately, ratio 3:1, have more problems than men. Fifty percent of women will experience incontinence issues at some point in their lives. Female incontinence is largely under-diagnosed and untreated. It is an embarrassing topic for many patients and few physicians routinely screen for urinary problems.

Symptoms reported can include incontinence (with or without stress), urgency, frequency, dysuria, nocturia or incomplete bladder emptying (with or without distention pressure). Many times a combination of symptoms is reported. These symptoms are an unreliable guide to the underlying dysfunction because the same condition or defect causes different symptoms over a cross-section of women and multiple causes may be present in any one patient.

Some forms of incontinence are acute and temporary:

1) Infectious—urethritis, cystitis or vaginitis can cause temporary incontinence.

2) Post-operative—from anesthesia effects, bladder over distention and/or fluid shifts that accompany hydration management.

3) Postpartum—from short-term perineal and pelvic pain, nerve stretching and edema; bladder over distention can also occur during a long labor.

4) Delirium or other psychogenic conditions where the patient becomes unaware of her bladder function.

5) Fecal impaction—resulting in obstructive overflow incontinence.

6) Medication induced—detailed below.

Possible acute causes of incontinence should be considered and promptly evaluated.

Many medications affect bladder and urethral function. Categories of disruption include medications that cause or increase urinary leakage, cause bladder muscle (detrusor) contractions or cause incomplete bladder emptying. Some antihypertensive medications cause urinary leakage by relaxing the urethral muscle. Other antihypertensives block the bladder detrusor function, causing overflow incontinence. Diuretics can cause rapid collection of urine in the bladder, increasing the likelihood of urinary leakage. Antidepressants, anxiolytics and muscle relaxants can also weaken the external urethral sphincter muscle. If there is compromise in the system, leakage easily occurs. Anti-seizure medications have an alpha-blocker effect associated with nighttime urinary loss. Medications that slow bowel function, like those prescribed for irritable bowel syndrome or Parkinsonism, can cause overflow incontinence. There are many more medications that contribute to bladder dysfunction.

The two most common types of chronic incontinence are genuine stress incontinence (GSI) and urge incontinence. GSI can be further sub-classified into a disorder of the bladder neck producing hypermobility (easily corrected) or intrinsic sphincter deficiency (very difficult to cure). Mixed incontinence is also frequently found, where elements of GSI and urge incontinence are present.

Less common forms of incontinence include overflow and neurogenic. Overflow incontinence results from urinary retention caused by an obstruction to urine flow. The sources of obstruction include pelvic organ prolapse, bladder neck fibrosis, urethral stenosis, urethral diverticula, urogenital cysts and tumors. Neurogenic incontinence can result from permanent localized pelvic floor nerve damage, brain/spinal nerve injury, neurologic diseases like multiple sclerosis, or peripheral neuropathy from chronic disease (particularly diabetes).

Diagnosing With Urodynamics

Urodynamics is the gold standard for investing the functional disorders of the bladder and urethra. Urodynamic studies generate objective results that can be combined with predominant symptoms, past medical history and medications, surgical history and a complete pelvic exam evaluating the present anatomy to assign the appropriate diagnoses.

Patient testing takes about 30 minutes. Mild discomfort can result from bladder distention and during catheter/transducer insertions. Commonly conducted tests include:

Capacity: The total amount that the bladder can hold.
Sensation: Subjective measurement of the patient’s first desire to void, normal desire to void and her maximum capacity or strong desire to void.
Compliance: The bladder’s ability to adjust to increasing volumes.
Detrusor Stability: The ability of the bladder muscle to stay inactive during filling and with the introduction of “stress” or provocation.

Uroflowmetry—Measures the amount and rate of urine from the bladder. Assesses for bladder emptying problems. Determines the need for pressure uroflowmetry.
Post-Void Residual—Measures the amount of urine in the bladder after voiding. Assesses efficiency of bladder emptying.
Cystometry—A bladder-filling study that measures the pressure to volume relationships in the bladder. This is the primary test used to reproduce and evaluate bladder dysfunction:

Pressure catheters are placed into the bladder to measure vesical pressure and into the vagina (or rectum) to measure abdominal pressure. The true detrusor pressure is the difference between the vesical and abdominal pressure. The bladder is a low-pressure system that should respond and correlate to abdominal pressure. When vesical pressure is greater than abdominal pressure, this indicates that the detrusor muscle is being independently engaged of the abdominal pressure forces. Stress, in the form of a cough, is introduced during the testing to examine for leakage and reaction of the detrusor muscle.

Valsalva Leak Point Pressure Study—Evaluates the competency of the urethral closure mechanism. Performed to differentiate between bladder neck hypermobility and intrinsic sphincter deficiency.
Urethral Pressure Profile—Evaluates the amount of pressure in the urethra. A confirmatory test for the type of stress incontinence.
Pressure Uroflowmetry—Measures the rate of voiding while simultaneously measuring bladder and vaginal pressures. Assesses muscle weakness and obstructive factors.
Electromyography (EMG)—Measures electrical activity during testing. Evaluates for muscle weakness and neurogenic factors.

Tests results are available immediately, at which time treatment options can be discussed. Treatments range from lifestyle modifications, medications, physical therapy/biofeedback, pessary usage and surgery. It is important to note that not all incontinence can be resolved, but with treatment, 80-85% of female incontinence can be greatly improved with a profound impact on quality of life.

J. Linn Daudel, M.D. is an OB/GYN specialist affiliated with Sutter Solano Medical Center in Vallejo. Urodynamic testing is available at her Benicia office at 707-745-3700.

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