Office-based cystometry identifies stress incontinence imposters. (Avoid Extensive Urodynamic Testing).

WASHINGTON -- About two-thirds of the patients who walk in your door with symptoms of stress incontinence actually have the disorder.

Identifying the other third doesn't necessarily require hauling out electronic urodynamic testing, Dr. Mark D. Walters said at a meeting on gynecologic surgery sponsored by the Washington Hospital Center.

Instead, the cystometrogram is a very cost-effective test that can be performed in the office to help pin down the diagnosis. About a fourth of all patients without true stress incontinence have unstable bladder or a mix of stress and urge incontinence. Another 5%-10% have other conditions such as neurogenic detrusor hyperreflexia associated with stroke or back trauma. And 2%-5% have some sort of voiding disorder.

Cystometry involves a simple, easily accomplished maneuver and is usually reimbursed by third-party payers. All that's required is a rubber catheter and a syringe with the rubber bulb taken out of it, which allows water to pour right into the bladder, said Dr. Walters of the Cleveland Clinic Foundation.

Have the patient start with a full bladder, ask her to void, and then get a straight catheter residual measurement. After that, start pouring in sterile water 50 mL at a time and ask her to tell you when her bladder feels full and then chart her capacity.

"If you do a lot of these, about twice a year someone will have no sensation. She'll get up to 800 cc and still feel nothing. That's when you've found that one overflow incontinence patient who you don't want to operate on," he said.

If the woman has an unstable bladder, she'll either have movement of the water column without doing a Valsalva maneuver, or she'll leak around the catheter.