Definitions

Stress urinary incontinence (SUI) is the complaint of involuntary loss of urine on effort or physical exertion (e.g. sporting activities) or on sneezing or coughing. Urodynamic stress incontinence (USI) is the involuntary leakage of urine during filling cystometry, associated with increased intra-abdominal pressure, in the absence of a detrusor contraction.

Diagnosis

The diagnosis may be established in three phases. The first two phases should provide enough information to establish the diagnosis in most patients. Phase III requires sophisticated urodynamic testing and is required only for certain women with risk factors such as previous surgical failures, combined SUI and urge urinary incontinence (UUI) symptoms, following radical pelvic surgery or radiation therapy, or when a negative Q-Tip test is identified.

Phase I

History and physical examination

A detailed questionnaire completed by the patient, followed by history taking, can guide the physician, but history alone is unreliable for establishing a diagnosis. Studies have shown that the history of “pure” SUI was urodynamically confirmed in 70–75% of cases, while the history of “pure” urge incontinence was urodynamically confirmed in only 50% of cases.

The physical examination should include the neurologic evaluation of the S2–S4 lower micturition center, since urinary incontinence may be secondary to central nervous system lesions. This evaluation includes testing the sensation in the inner thighs, perirectal, and vulvar areas (sensory dermatomes representing S2–S4). The bulbocavernous reflex, a gentle squeeze or tap to the clitoris resulting in reflex contraction of the perirectal muscle, confirms an intact motor component of S2–S4, where the lower micturition center is located; however, it is not often used in common practice due to patient discomfort. The anal wink reflex, a reflex contraction of the anal sphincter in response to stroking the perianal skin, is more commonly applied clinically but may be absent in 20% of neurologically intact women.

Postvoid residual

Although overflow incontinence is unusual in women, it is essential to rule it out in the initial phase of diagnosis. Measurement of postvoid residual (PVR) urine volume is useful in this respect. The volume of urine remaining in the bladder after spontaneous voiding is measured by catheterization or ultrasound. To be useful, the volume voided should be greater than 200 cc. There is no consensus as to what is considered a normal PVR, but most specialists in the field define it as either less than 50 mL and/or less than 20% of the total voided volume. Isolated elevations of PVR should be confirmed by repeat evaluation. If the PVR is consistently greater than 200 mL, overflow incontinence is suspected.

Urinalysis, urine culture and sensitivity

A midstream urine culture should be taken at the time of initial evaluation. Urinary infection can masquerade as any lower urinary tract pathology, including SUI or UUI. Diagnosis of incontinence made at the time of unsuspected urinary tract infection is inaccurate in at least half of patients.

Bladder diary

Bladder diaries are patient recordings of the time and volume of all fluid intake as well as continence and incontinence voids. Clinically, 3-day diaries are most commonly used. Diaries can provide information on the usual timing and circumstances of urinary incontinence, amount of urine per void, voiding frequency, and urinary incontinence frequency, and the total daytime and nocturnal urine output.

Phase II

Cystourethroscopy

Cystourethroscopy may be performed in the clinic using either carbon dioxide or a fluid medium, although fluid medium is fairly standard. The cystourethroscope is used to examine the urethra, trigone and bladder for gross pathology. The urethrovesical junction (UVJ) is examined dynamically. The response to “hold urine,” in the absence of peripheral neuropathy, should be that the UVJ will close. The response to cough and the Valsalva maneuver should also be that the UVJ should close as a reflex mechanism; in SUI and weak urethral sphincter, the UVJ often funnels and opens with cough or Valsalva. The cystourethroscope is slowly withdrawn along the urethra while it is distended, allowing a thorough examination for diverticula, which may simulate SUI or exudate, since urethritis may simulate UUI.

Cotton-tipped swab (Q-Tip) test

A sterile cotton-tipped swab, lubricated with lidocaine jelly, is introduced into the urethra and advanced to the UVJ. Using the orthopedic goniometer, the resting and straining angles of the Q-Tip to the horizontal are measured. There is no consensus as to what defines a positive Q-Tip test, but a starting angle greater than 45º or a change of greater than 30º is generally indicative of poor support of the UVJ. A negative Q-Tip test should raise doubt about the diagnosis of SUI and more sophisticated urodynamic tests should then be ordered.

Stress test or simple (single channel) cystometry

For women with isolated SUI symptoms without other risk factors such as prior incontinence surgery, negative Q-Tip, a history of radiation therapy or a history of radical pelvic surgery, a stress test or simple cystometry may be sufficient. The stress test is performed by asking the patient to stand and cough with a full bladder.

Simple cystometry is performed with a single catheter in the bladder, in the standing position, with periodic cough provocations. The bladder is usually filled with a fluid medium (saline or sterile water), and the intravesical (bladder) pressures are measured during the procedure. An increase in intravesical pressure >15 cm H2O above baseline suggests detrusor overactivity (DO). Increased intra-abdominal pressure, such as with Valsalva, will also result in an increase in intravesical pressure and cannot be differentiated from DO on simple cystometry. DO should always be ruled out before the diagnosis of SUI is established since bladder contractions induced by cough can result in symptoms and clinical findings of SUI. If simple cystometry suggests DO, then multichannel urodynamics is indicated.

In cases of pure SUI where cystourethroscopy demonstrates a weak sphincter and no other pathology, the Q-Tip test demonstrates poor support to the UVJ, and the stress test or simple cystometry does not suggest DO, the diagnosis of SUI can be established, and the phase III evaluation is not required. If any of these tests is inconsistent with SUI, phase III urodynamic evaluation is necessary.

Phase III

Multichannel urodynamics

Concomitant pressures in the bladder, urethra, and abdomen are recorded with catheters placed in the bladder, urethra and vagina or rectum, respectively, while filling the bladder with fluid medium. Detrusor pressures (pressure generated by the detrusor muscle of the bladder) can be calculated by subtracting abdominal pressure from intravesical pressure. If a rise in intravesical pressure is seen, these multiple recordings allow for determination as to whether this rise is due to DO or an increase in intra-abdominal pressure such as with Valsalva. A detrusor contraction is defined as a rise in detrusor pressure > 15 cm H2O above baseline or > 10 cm H2O above baseline with associated urgency.