388 Obstetrics and Gynecology Board Review •••
❍ Why is the distinction between GSUI and ISD important?
There is a higher failure rate with midurethral transobturator pubovaginal sling procedures in patients with ISD.
These patients should be treated with retropubic suburethral slings or bulking agents.
❍ What type of suburethral sling is more effective for patients with ISD?
Retropubic slings are the most effective type of midurethral pubovaginal slings for patients with ISD.
❍ When is UDT?
Urodynamic testing is a global term referring to various quantitative metrics regarding both filling/storage of the
urinary tract and the emptying phase. This includes uroflowmetry, cystometrogram, pressure voiding studies,
urethral pressure profiles, and measurement of postvoid residual volume.
❍ When is UDT indicated?
Newer research demonstrates that UDT is not indicated for uncomplicated/direct diagnosis of SUI but maybe
indicated for patients with suspected ISD or mixed UI.
❍ What is complex cystometry?
Multichannel cystometry is a more sophisticated method of measuring filling cystometrography. With this
technique, intravesical pressure (Pves), intra-abdominal pressure (Pabd), detrusor pressure (Pdet), and maximum flow
rate (Qmax) are recorded simultaneously.
Usually, the patient feels the first sensation as the bladder begins to fill with 100–200 mL of water. As the
bladder nears capacity, 300–400 mL, the patient may begin to feel uncomfortable, and a true urge to void will.
An average adult bladder capacity is approximately 450–500 mL. During the test, provocative maneuvers (eg,
coughing and straining) may help to unveil bladder instability or demonstrate genuine stress urinary incontinence.
A pressure-flow study simultaneously records the voiding detrusor pressure and the rate of urinary flow.
Voiding cystometrography is the only test able to provide information about bladder contractility and the extent of
a bladder outlet obstruction.
❍ What are the classic findings on UDT with stress incontinence?
On Valsalva, there is an increase in abdominal and vesical pressures, the detrusor pressure remains the same
(no increase), and there is urinary leakage. Urethral pressure may increase slightly, but it is less than the vesical
pressure, thus the urethral closure pressure is negative, allowing urinary leakage.
❍ What are the classic findings on UDT with detrusor overactivity?
On filling the bladder with fluid, there is an increase in vesical pressure, and abdominal pressure has little or
no increase in pressure. The true detrusor pressure (vesical pressure-abdominal pressure), therefore, is positive
(represented by an increased pressure curve on the tracing). This increase in pressure is usually associated with a
sense of urgency. If there is associated incontinence, then the diagnosis of detrusor overactivity incontinence or
urge incontinence is made. The urethral pressure should stay the same or may increase if the patient attempts to
suppress the urge to void.
❍ What are treatment options for patients with OAB?
Anticholinergic medications are first line as well as behavior modifications. Patients who are refractory to these
modalities can be candidates for Botox and electrical nerve stimulation devices.