Hysterectomy is a common and safe surgical procedure. A recent meta-analysis has shown, however, that the operation carries an increased likelihood of urinary incontinence as a long-term adverse effect.

Introduction

In the USA, hysterectomy is the second most common major surgical procedure, after cesarean section. Indeed, about 40% of women have had a hysterectomy by the age of 60. Nearly all these operations are done for benign disorders, such as fibroids, vaginal bleeding, pelvic pain and uterine prolapse. Fever is the most common postoperative complication, seen in 25% of patients. Serious complications, such as hemorrhage requiring transfusion, are reported in about 10% of cases, and the mortality rate is 6 per 10,000 hysterectomies. These figures indicate the operation to be a safe procedure. However, one particular long-term complication may be commoner than expected.

The procedure of hysterectomy can damage the pelvic nerves or the pelvic support structures, either of which may increase the risk of urinary incontinence. The authors of this meta-analysis have studied the frequency of urinary incontinence in subjects who have had a hysterectomy, compared with its occurrence in those with an intact uterus.

Method

MEDLINE was searched for a 2-year period (January 1996 to December 1997) using the keywords: hysterectomy, genital surgery, and urinary incontinence. Other literature sources referred to in the articles found were also searched.

A total of 45 articles were identified, out of which 12 provided data on urinary incontinence in women who had hysterectomies compared with those who did not. For each of these studies the most adjusted odds ratio and 95% confidence interval (95% CI) were used to calculate summary estimates. If odds ratios were not reported, the authors calculated them from data provided in the publication, or obtained from the study investigator. If odds ratios or relative risks could not be obtained, the study was excluded from the meta-analysis.

Summary odds ratios were calculated for the collective of studies, as well as for sub-groups of subjects above and below 60 years, and for total vs. supracervical (partial) hysterectomy.

Results

Of the 12 studies, eight were cross-sectional, two were prospective cohorts, one was case-control, and one a randomized controlled study. Thus 11 of the 12 were observational studies.

The 11 observational studies provided a summary odds ratio for urinary incontinence of any type in women with hysterectomy of 1.4 (95% CI 1.2 to1.7, p<0.01). When these findings were stratified by age at the time of assessment of incontinence, it was found that in women aged 60 or older there was a 40% to 80% higher prevalence of incontinence in women who had undergone hysterectomy (odds ratio 1.6, 95% CI 1.4 to 1.8). In women under 60 the odds ratio was 1.1 (1.0 to 1.4, p=0.03); this latter ratio remained unchanged when one study with considerable heterogeneity was excluded.

The types of incontinence (stress, urge, or mixed incontinence) were insufficiently documented in enough studies to allow calculation of a summary odds ratio. There were no data that showed that total hysterectomy was associated with a greater likelihood of incontinence than supracervical hysterectomy.

Comment

The results of the 11 studies used in this meta-analysis indicated that the odds of women developing urinary incontinence after hysterectomy are about 40% higher than for women who have not had the operation. The odds were increased to 60% higher for women over 60 years at their first assessment for incontinence, presumably because the incontinence does not develop for several years after hysterectomy.

The reason for the delayed appearance of incontinence is unclear. However, its timing resembles that associated with childbirth. Loss of pelvic floor innervation has been reported shortly after childbirth, but incontinence is not increased substantially until 5 to 10 years later.

Some investigators have suggested that total hysterectomy is more likely to cause damage to the pelvic floor nerves than supracervical hysterectomy, but the analyses made here do not support this.

The frequency of hysterectomy differs considerably in various countries, but it is unlikely that operative techniques are sufficiently varied to make a difference in long-term outcome. Hysterectomy is largely a selective rather than an emergency procedure. It would seem appropriate, therefore, based on these findings, to council women preoperatively about the slight but real increased risk of incontinence developing years after the operation.

Other risk factors for urinary incontinence are reviewed in "Preventing Incontinence", together with ways to minimize them.

Source

• Hysterectomy and urinary incontinence: a systematic review. JS. Brown, G. Sawaya, D. Thom, D. Grady, Lancet, 2000, vol. 356, pp. 535--539