Tubal sterilization: findings in a large prospective study

Abstract

Of the 17032 women taking part in a large prospective study of the beneficial and harmful effects of different contraceptive methods, 2243 (13%) had undergone tubal sterilization by the end of 1981 while another 3551 (21%) had husbands who had undergone vasectomy. The most commonly used female sterilization procedure was laparoscopic tubal diathermy. About 19% of all operations were carried out at the time of a delivery or during the subsequent 4 weeks. In total, 16 accidental pregnancies have occurred in the sterilized women, the failure rate during the 12 months after surgery being 0.37 per 100 woman-years and the rate during the subsequent months being 0.10 per 100 woman-years. Of the 16 accidental pregnancies, seven were ectopic. In an analysis comparing women who had undergone tubal sterilization with those whose husbands had undergone vasectomy, there was little evidence of any excess occurrence of gynaecological or psychiatric disorders in the former group.A prospective study was initiated at 2 family planning clinics in 1968 with a view toward providing a balanced view of the beneficial and harmful effects of different contraceptive methods. The method of investigation proved successful, and the study was subsequently extended to a total of 17 clinics in different parts of England and Scotland. By mid 1974, when recruitment was discontinued, a total of 17,032 women had joined the study, and they have remained under observation ever since. Over the years a substantial proportion of these women (or their husbands) chose to be sterilized. Findings about the frequency, methods, efficacy, and sequelae of tubal sterilization among the survey participants are summarized. At recruitment time, each woman had to be between 25-39 years of age, married, a white British subject, willing to participate, and either a current user of oral contraceptives (OCs) of at least 5 months standing or a current user of a diaphragm or an IUD of at least 5 months standing without prior exposure to OC. By the end of 1981, 2243 (13%) of the 17,032 women had undergone a tubal sterilization procedure. Another 3351 women (21%) had husbands who had undergone vasectomy. The most common female sterilization procedure used was laparoscopic tubal diathermy (776 operations) while tubal ligation at laparotomy came a close second (637 operations). About 19% of the female sterilization operations were performed at the time of delivery or during the subsequent 4 weeks. Open rather than laparoscopic sterilization procedures were more commonly used in the 1968-71 period, but the reverse was the case subsequently. 15 women were known to have experienced failure of tubal sterilization. 1 woman experienced failure twice and thus was sterilized 3 times. The failure rate during the 12 months after surgery (0.37/100 woman years) was almost 4 times higher than the failure rate during subsequent months (0.10/100 woman years). Overall, it was estimated that of every 1000 women undergoing tubal sterilization about 4 would have experienced a pregnancy after 1 year, about 8 after 4 years, and about 10 after 7 years. A reversal operation is known to have been undertaken in only 2 women, and 1 of the 2 reversals was successful. Of the 16 accidental pregnancies, 7 were ectopic. In an analysis comparing women who had undergone tubal sterilization with those whose husbands had undergone vasectomy, there was little evidence of any excess occurrence of gynecological or psychiatric disorders in the former group.