Emergency contraception and ectopic pregnancy: report of 2 cases.

The incidence of ectopic pregnancy has been increasing over the last few years, reaching a value of 1 case in 80 pregnancies, and it continues to be the main cause of maternal death during the first trimester in the United States. The main causes of tubal ectopic pregnancy, which generally results from damage to or dysfunction of the fallopian tubes, are salpingitis, previous tubal surgeries, and alteration in tubal motility mainly due to the use of certain contraceptive methods. Emergency contraceptive methods have been developed to prevent undesired pregnancies after unprotected sexual intercourse and have been used for more than 20 years. The most commonly employed methods are (a) the Yuzpe regimen, which recommends the administration of 2 doses of 100 μg ethinyl estradiol and 500 μg levonorgestrel at 12hour intervals, and (b) the exclusive use of 750 μg levonorgestrel in 2 doses separated by a 12-hour interval. The latter method has been applied in some countries since 1979, but only in 1994 did a coordinated study by the WHO show that its efficacy was superior to that of other emergency contraceptive methods available at the time. 9 Pulkkinen and Talo described the physiology of tubal ciliary and myoelectrical activity. The static force of the cilia results in fluid flow toward the uterus; the spermatozoa overcome this, and cilia are not obligatory for normal implantation, since patients with congenital inactivity of all cilia (Kartagener ́s syndrome) are able to have intrauterine pregnancies. It is the myoelectrical activity that plays a vital role in tubal propulsion. In general, estrogens stimulate tubal myoelectrical activity and progesterone inhibits it. The mechanisms of the contraceptive action of levonorgestrel are believed to be multifactorial. Among these mechanisms, alteration in tubal motility may contribute to a delayed arrival of the egg in the endometrial cavity, a fact leading to the occurrence of ectopic pregnancy. Moreover, pharmacologic levels of progesterone may relax tubal myoelectrical activity to such an extent that transport through the isthmus does not occur. We report here 2 cases of ectopic pregnancy that occurred after the use of emergency contraceptive pills containing 0.75 mg levonorgestrel (Postinor 2) by women without apparent risk factors for ectopic pregnancy.