Based on a variety of questionnaires, the researchers found that after 12 months, surgery was successful in about 77 percent of women who did or didn't get additional testing.

They also found the extra testing made no difference when it came to quality of life, patient satisfaction, voiding problems or other measures.

And although findings from the extra tests often led doctors to change their specific incontinence-related diagnosis, that didn't affect how they managed patients surgically, according to findings published Wednesday in the New England Journal of Medicine.

"We therefore question the clinical importance of such diagnostic changes," the researchers concluded.

Dr. J. Quentin Clemens of the University of Michigan Medical Center in Ann Arbor, a urologist who wasn't connected to the research, said that although this type of study hadn't been done before, the findings are consistent with what urologists would anticipate and with guidelines from the American Urological Association.