Long-term risk of hysterectomy after tubal sterilization.

Previous studies with only short-term follow-up have produced conflicting results on whether a tubal ligation increases a woman's risk for having a hysterectomy. By use of population-based data from the province of Manitoba's universal health insurance plan, all women aged 25-44 years who had a tubal ligation in 1974 (n = 4,374) were identified. As a comparison group, a random sample of 10,000 Manitoba women who were registered with the insurance plan on July 1, 1974 was chosen. Women undergoing hysterectomy prior to July 1, 1974 or a tubal ligation from 1970-1982 were excluded, leaving 6,835 in the comparison group. All health care utilization for two years before tubal ligation or July 1, 1974 (comparison group) was recorded to identify health characteristics of the women. Information was recorded on rate of hysterectomy, dilatation and curettage, all hospitalization, and hospitalization for menstrual disorders for two years after tubal ligation or July 1, 1974. For the longer term analysis, information on hysterectomy up to December 31, 1982 was recorded. At two years there was no increase in adverse gynecologic outcomes between the two groups. Survival curves (life table method) comparing the two groups for up to nine years found higher hysterectomy rates for women aged 25-29 beginning at two years after tubal ligation and increasing with time. Multivariate analysis (Cox's regression model) confirmed that for women aged 25-29, tubal ligation increased the probability of a hysterectomy 1.6 times (1.2-2.3, 95% confidence interval) after controlling for previous gynecologic history, marital status, number of physician visits, and hospitalizations. For women aged 30 and over, tubal ligation was not a risk factor for subsequent hysterectomy in either the short or long term.