CDC Researchers Report Increased Risk of Ectopic
Pregnancy After Tubal Sterilization

Researchers from the Centers for Disease Control and Prevention (CDC), and others, report that ectopic pregnancy after tubal sterilization is more common than previously thought. Ectopic pregnancy, also known as a tubal pregnancy, is a potentially life-threatening form of pregnancy where implantation of the fertilized egg occurs outside the uterus.

Among 10,685 women studied, the risk of ectopic pregnancy within 10 years after sterilization was about 7 per 1,000 procedures. These findings are reported in the Mar. 13, 1997, issue of the New England Journal of Medicine.

The purpose of this 14-year study, which was supported by the National Institute of Child Health and Human Development (NICHD) at the National Institutes of Health, was to assess the risk of ectopic pregnancy in women who have undergone tubal sterilization.

"We Would like all women undergoing this procedure to be informed that ectopic pregnancy may occur long after sterilization. Ectopic pregnancy after tubal sterilization is not rare, particularly among women sterilized before age 30," said Dr. Herbert Peterson of CDC's National Center for Chronic Disease Prevention and Health Promotion, principal author of the report.

"Those who provide care to women of childbearing age should not assume that a history of tubal sterilization rules out the possibility of an ectopic pregnancy in a woman who has symptoms or signs of pregnancy, especially ectopic pregnancy," Peterson said.

The study also found that the likelihood of an ectopic pregnancy varied according to the method of sterilization and the age at which the women underwent the sterilization procedure. Women who were under age 30 at the time of the procedure were twice as likely to have a subsequent ectopic pregnancy as older women. Further, the researchers found that ectopic pregnancy may occur many years after tubal sterilization.

"These findings mean that women who have undergone tubal sterilization and their physicians should consider the possibility of ectopic pregnancy and take appropriate steps quickly if those patients think they may be pregnant or have developed symptoms of ectopic pregnancy," said Dr. Steven C. Kaufman of NICHD and project officer for the study. Symptoms of ectopic pregnancy include pelvic pain and vaginal bleeding.

According to Peterson, tubal sterilization is an increasingly common method of contraception in the United States, and even though pregnancy after sterilization is uncommon, it can occur, and it may be ectopic.

Women who think that they might be pregnant after sterilization should check with their health care providers, even if the sterilization was performed many years earlier, Peterson says.

Approximately 100,000 ectopic pregnancies occur each year and relatively few are caused by sterilization. Often the actual cause is unknown, but many cases result from tubal damage incurred from sexually transmitted infections. Ectopic pregnancies are the leading cause of pregnancy-related deaths in the first trimester and account for nine percent of all pregnancy-related deaths in this country.

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