Postcoital or emergency contraception (ECP) maybe used for women who experience unprotected sexual intercourse. Making postcoital contraception widely and easily available is one of the most important steps that can be taken to reduce the high rates of unintended pregnancy and abortion. It is estimated that the regular use of postcoital contraception would prevent more than 1.5 million unintended pregnancies in the United States each year.
Combined oral conceptive regimens used for emer-gency contraception, known collectively as the Yuzpe method, were first reported by Albert Yuzpe in 1974. These regimens require taking 2 tablets within 72 hours of unprotected intercourse, followed by another two tablets in 12 hours. Subsequently, the use of a progestin-only regimen, known as “Plan B,” was approved for behind-the-counter dispensing to women over 18 years of age without a prescription. Plan B consists of two tablets of levonorgestrel taken 12 hours apart. This method is asso-ciated with a lower incidence of nausea and emesis than the Yuzpe method and with greater effectiveness. Both methods act by preventing ovulation and fertilization, and will not terminate an existing pregnancy. Emergency contraception can also be accomplished with a copper-containing IUD.
The failure rate for the Yuzpe regimen is estimated at 25%; for Plan B, 11%. Multiple unprotected coital events or an interval greater than 72 hours may be associated with an increasing failure rate, although some evidence of suc-cess is seen out to 120 hours after unprotected intercourse. If the woman is already pregnant, these medications have no ill effect on the fetus. The amount of hormone in these regimens is not associated with alterations in clotting fac-tors or teratogenic risk.
The copper IUD is another recommended option for emergency contraception (except in patients with Wilson disease) and, in limited studies, has a failure rate of approx-imately 0.1%. An additional advantage of IUD insertion is the contraceptive effect that is provided for up to 10 years. Before using this method, a pregnancy test is required be-cause of the risk to an implanted pregnancy.