Emergency Postcoital Contraception
|Combined Oral Contraceptives|
|Management of Gastrointestinal side Effects|
|After 72 Hours|
As a birth control option, emergency postcoital contraception is highly effective but underutilized. Its use could result in 1 million fewer abortions and 2 million fewer unintended pregnancies each year in the United States. Although 2 to 3 percent of women terminate a pregnancy each year through abortion, only 1 percent of women in America report using emergency contraception. It should be a primary prevention health service to women of childbearing age.
The probability of conception when emergency
contraception should be considered is often unclear or misunderstood.
the average fertile period for a woman lasts only six days per menstrual
cycle and ends the day she ovulates. Unprotected sex three days before
ovulation results in an estimated 15 percent pregnancy rate; one or
two days before ovulation, about 12 percent. Sperm can survive in the
female up to five days and the mature egg may be fertilized over a 24-hour
period. The time period from ovulation to implantation is about seven
(1) Combined Oral Contraceptives: Uses estrogen-progestin combinations (ethinyl estradiol and norgestrel/levonorgestrel) - also known as the Yuzpe regimen after Albert Yuzpe, whose research on high-dose estrogen regimens led to the current treatment protocols. The efficacy of combined regimens that contain a progestin other than norgestrel/levonorgestrel has not been studied.
(2) The progestin-only minipill (levonorgestrel).
(3) The Copper-T 380 intrauterine device (IUD).
(4) Antiprogestins - Low doses of antiprogestin synthetic steroid RU 486 (mifepristone, Mifeprex) have been shown to be equally or more effective than existing oral regimens for postcoital contraception. However, these products are not readily available.
Management of Gastrointestinal Side Effects of Emergency Contraceptive
While somewhat less effective than combined preparations when used as a regular birth control method, the progestin-only minipill may outshine the former when it comes to emergency use. Not only is its efficacy thought to be greater, but nausea and vomiting are significantly less common, and it can be used even by women who cannot tolerate estrogen. The catch is that the required dosage of levonorgestrel, 0.75 mg may be unavailable in a single- or two-tablet format. In order to obtain postcoital protection, a woman must ingest two doses of 20 tablets each of norgestrel 12 hours apart, beginning within 72 hours of exposure. (Only half of the norgestrel pill consists of levonorgestrel; hence, the necessity for 20 tablets.) Faced with such an inconvenient and expensive regimen, most patients are willing to overlook the gastrointestinal effects associated with the combined preparations.
T-380 A Intrauterine Device
The Copper-T IUD will prevent pregnancy up to five days following unprotected intercourse. Although not suitable for all women, the device is significantly more effective than either form of oral emergency contraception, reducing the risk of pregnancy by 99%.
Mechanism of action: Not firmly established, depending on the timing of insertion, may interfere with sperm transport or implantation. Because the method prevents implantation, an IUD may be inserted up to five days after the earliest estimated date of ovulation.
Side effects and risks are the same as those for IUD insertion at other times. If left in place, it will provide continuous effective contraception for up to 10 years. However, potential users should be carefully screened, as insertion may not be advisable in women who have elevated risk for PID or other sexually transmitted infections. Use is not recommended in women who have been raped, as they may have been exposed to sexually transmitted disease in the process. For women who are not at risk for STD, the health risks associated with IUD use are very low.
Contraindications: Confirmed or suspected pregnancy is a contraindication to the IUD, as presence of the device may cause spontaneous abortion, septic second-trimester abortion, or premature delivery.
RU 486 (Mifepristone)
Mifepristone inhibits ovulation and blocks implantation by causing a delay in endometrial maturation. It causes an actual regression of the corpus luteum in 50 percent of women when given in the middle or late luteal phase. Only mifepristone is effective once implantation has occurred, actually interrupting an early pregnancy.
In trials, RU 486, given as a single 600-mg dose within 72 hours after unprotected intercourse, was 100% effective as an emergency contraceptive. Other doses, 50 mg or 10 mg, given as a single dose within five days of unprotected sex were also effective in decreasing pregnancy rate by 85 %.
Dose: 10 mg, 50 mg, 600 mg
Timing of first dose after intercourse: 0 to 120 hours
Reported efficacy: 85 to 100% effective
Side effects: Less nausea and vomiting than the Yuzpe regimen. 18 % to 36 % of women experienced delay of menses of more than three days. The side effects were significantly related to the dose of RU 486 used.
|After 72 Hours
What is the patient presents for care after 72 hours have passed, and the IUD is not an option? While we know that treatment efficacy does not drop to zero 73 or 74 hours after exposure, there obviously is a cutoff, somewhere around one week, beyond which an oral agent would be futile. Prior to that point, the decision of whether or not to proceed becomes a judgment call on the part of the patient and the physician. Although intervention may not succeed, it might be worth a try if the patient wants it, with the reassurance that no harm will be done is she becomes pregnant.
Like vaccine-preventable diseases, emergency contraception is an area of need in which, historically market forces have not provided sufficient impetus for new product development. This has remained the case despite encouragement from numerous professional organizations and even the FDA. Given the extensive societal costs of unplanned pregnancy, it seems logical for government agencies to step in at this point and offer appropriate incentives - such as liability protection - that could prompt pharmaceutical companies to address this important need. In the interim, physicians should inform patients about the availability of emergency contraception and consider prescribing or dispensing pill packs in advance, to give patients the option of initiating therapy with minimal fanfare.