Examining the Evidence
Does hysterectomy raise the risk of stress-incontinence surgery?
Yes. This population-based cohort study from Sweden found that hysterectomy for benign indications by itself doubles the risk of future surgery for urinary stress incontinence, regardless of hysterectomy technique. The risk of stress-incontinence surgery varied with the length of follow-up, with the highest overall risk observed within 5 years of hysterectomy and the lowest risk after 10 years or more (2.7 versus 2.1).
Urologists, among others, have long suspected that hysterectomy is somehow implicated in the development of stress incontinence, a point of view that has met with considerable resistance from gynecologists. Now comes this carefully designed study by Altman and colleagues, which lends considerable support to this belief.
Strengths of the study include use of Swedish health registry
The study design used by the authors is impressive. Because Sweden (unlike the United States) has a national health-care system with an integrated national database, the authors were able to select more than 165,000 women from the Swedish health registry who had undergone hysterectomy (the “exposed” cohort) and compare them with almost 480,000 women who had not had a hysterectomy (three controls for every exposed case), matching them by year of birth and county of residence. Because of the integrated nature of the Swedish health registry, they were able to follow these women for 30 years and link their medical records to subsequent surgical procedures for urinary stress incontinence.
The authors eliminated from consideration any patient whose surgery had been done for malignancy. Because patients undergoing hysterectomy for pelvic organ prolapse might well be predisposed to develop stress incontinence in later life, the authors considered as a separate subset those women whose hysterectomy was done for prolapse or who had an associated procedure performed for prolapse at the same time.
As might be expected, women who underwent hysterectomy for prolapse had the highest risk of undergoing stress-incontinence surgery within 5 years of the removal of their uterus.
Vaginal delivery magnified the impact of hysterectomy
Altman and colleagues also considered the impact of vaginal delivery on subsequent surgery for stress incontinence, finding an additive effect. There was a “dose-response” increase in risk related to the number of vaginal births. Women who had four vaginal deliveries had a sixfold increase in the risk of stress incontinence surgery, and women who had four vaginal deliveries plus a hysterectomy had a 16-fold increase in the risk of stress-incontinence surgery.
Were some women predisposed to elective surgery?
Because surgery for urinary stress incontinence is an elective procedure to improve quality of life, the argument could be made that the women who chose this form of therapy had a lower threshold for elective surgery. The authors attempted to control for this by analyzing the likelihood of undergoing osteotomy of the great toe (hallux valgus surgery) and varicose vein stripping. They found no meaningful association between these elective operations and hysterectomy or stress-incontinence surgery.
“Escalator effect” may be involved
An important question that this study is unable to answer concerns the “escalator effect.” Because urinary stress incontinence is highly prevalent, it affects many women who also have other, more pressing gynecologic complaints. We do not know how many women had stress incontinence that was much less troubling than, say, leiomyomata or dysfunctional uterine bleeding and who, after these problems were solved by hysterectomy, then had their attention increasingly focused on this new complaint, which then moved higher up their list of concerns as other problems were treated.
The authors also acknowledge that other behavioral and lifestyle factors that are probably associated with stress incontinence, such as smoking, strenuous work, and elevated body mass index, were not accounted for in their study.
Should this study alter clinical practice?
Women undergoing hysterectomy should probably be informed that the operation may increase the likelihood of their undergoing surgery for stress incontinence later in life. In some cases, this information may lead women to reconsider the need for elective hysterectomy, but a possible future risk of undergoing a generally safe and effective operation for stress incontinence is unlikely to be determinative for most women who are contemplating surgery for other debilitating gynecologic conditions that can be treated permanently and effectively by hysterectomy.