Researchers analyzed data from more than 165,000 Swedish women who had hysterectomies and almost half a million women who did not.
The study showed that the women who had hysterectomies were more than twice as likely to have a later surgery to improve stress urinary incontinence.
Earlier, smaller studies have been mixed, with some showing an increased risk for incontinence in women who have undergone hysterectomies and other studies showing no such risk.
Researcher Daniel Altman, MD, tells WebMD that the latest findings provide strong evidence of a link.
"Any woman contemplating an elective hysterectomy should be told that there may be consequences in the future," he says. "The jury has been out, but I think the evidence is clear."
Stress Incontinence Common
About 600,000 women in the U.S. have hysterectomies each year, and the vast majority of the procedures are done for conditions such as irregular heavy menstrual bleeding and uterine prolapse.
Far more women -- as many as 45% by some estimates -- suffer from some degree of stress incontinence, defined as involuntary urine loss associated with activities such as laughing, coughing, sneezing, and exercise.
"We know that there are many, many women with this problem who are never treated," Altman says. "That is why it is important to look for better ways to prevent it."
Using data from a nationwide Swedish hospital discharge registry, Altman and colleagues were able to follow 165,260 women who had hysterectomies and 479,506 similarly aged women who did not have hysterectomies for three decades to determine if they later had surgery to relieve stress incontinence.
Women who had hysterectomies were 2.4 times more likely to have a subsequent surgery for incontinence, regardless of the type of hysterectomy procedure they had undergone. The greatest risk of incontinence was within five years of the first surgical procedure.
Women who had more than one vaginal birth were also at increased risk.
Hysterectomy May Not Be to Blame
The study is published in the Oct. 27 issue of the journal The Lancet.
"We conclude that hysterectomy, irrespective of surgical technique, increases the risk for stress urinary incontinence surgery later in life," the researchers write.
But gynecologic surgeon Adam Magos, BSc, MD, is not convinced.
In an editorial accompanying the study, Magos writes that there has been no consensus on whether hysterectomy increases a woman's risk for urinary incontinence, pointing out that an earlier study from the same research group suggested that it does not.
He notes that the difference in outcomes may be due to the fact that women who have hysterectomies may be more likely to consider surgery an appropriate treatment for stress incontinence.
"Perhaps it has nothing to do with hysterectomy, and women who agree to hysterectomy are just different in ways that we do not yet understand," he writes.