Risk of urinary incontinence rises after hysterectomy.

Women who undergo hysterectomy for benign indications are more than twice as likely to develop stress urinary incontinence requiring surgery, according to data from a large cohort study.

Dr. Daniel Altman and colleagues from the Karolinska Institute, Stockholm, compared 165,260 women who had undergone hysterectomy between 1973 and 2003 with three times as many control women matched by year of birth and county of residence (Lancet 2007;370:1494-9).

The investigators excluded women who had stress-urinary-incontinence surgery (SUIS) before their hysterectomies, women whose hysterectomies were done for malignant conditions, or women listed in a national cancer registry at the time of their hysterectomy.

During an average follow-up period of 12 years, women in the control group underwent SUIS at a rate of 76 per 100,000 person-years, while women in the hysterectomy group underwent SUIS at a rate of 179 per 100,000 person-years, a significant difference.

The greatest increase in risk occurred among women aged 58 years or older, with a hazard ratio of 3.1. Women aged 45-49 years had the lowest increase in risk, with a hazard ratio of 2.0.

The risk was greatest between 0 and 5 years after surgery, with a hazard ratio of 2.7. That number dropped to 2.5 between 5 and 10 years and to 2.1 more than 10 years following surgery.

Among the women in the control group with four or more vaginal deliveries, the risk of SUIS was almost sixfold higher than in those with no vaginal deliveries. In the hysterectomy group, that risk was almost 16-fold higher.

In an editorial, Dr. Adam Magos of the Royal Free Hospital, London, cited contradictory results from earlier studies. "It seems likely that a simple hysterectomy does not adversely affect bladder function at least initially, and indeed pre-existing symptoms may improve," he wrote (Lancet 2007;370:1462-3). "If hysterectomy-induced urinary stress incontinence is a reality, it only becomes so several years after the surgery.... Or 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."