THE RISK OF ECTOPIC PREGNANCY AFTER TUBAL-STERILIZATION

Background Tubal sterilization is an increasingly common method of con traception in the United States. Although pregnancy after sterilizatio n is uncommon, it can occur and may be ectopic. We used data from the U.S. Collaborative Review of Sterilization to estimate the risk of ect opic pregnancy in women who had undergone the common types of tubal st erilization. Methods A total of 10,685 women undergoing tubal steriliz ation were followed in a multicenter, prospective cohort study. We int ended to follow all the women for 5 years by means of annual telephone interviews; for women enrolled early in the study, we attempted an ad ditional follow-up telephone interview 8 to 14 years after sterilizati on. To assess the risk of ectopic pregnancy in these women, we used cu mulative life-table probabilities and proportional-hazards analysis. R esults There were 47 ectopic pregnancies in the 10,685 women; the 10-y ear cumulative probability of ectopic pregnancy for all methods of tub al sterilization combined was 7.3 per 1000 procedures. The cumulative probability varied substantially according to the method of sterilizat ion and the woman's age at the time of sterilization. Women sterilized by bipolar tubal coagulation before the age of 30 years had a probabi lity of ectopic pregnancy that was 27 times as high as that among wome n of similar age who underwent postpartum partial salpingectomy (31.9 vs. 1.2 ectopic pregnancies per 1000 procedures). The annual rate of e ctopic pregnancy for all methods combined in the 4th through 10th year s after sterilization was no lower than that in the first 3 years. Con clusions A history of tubal sterilization does not rule out the possib ility of ectopic pregnancy, even many years after the procedure. (C) 1 997, Massachusetts Medical Society.