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Contraception

Elizabeth K. Stanford, MD

One-half of unplanned pregnancies occur among the 10 percent of women who do not use contraception. The remainder of unintended pregnancies result from contraceptive failure.

Diaphragm

Diaphragms function as a physical barrier and as a reservoir for spermicide. They are particularly acceptable for patients who have only intermittent intercourse. Diaphragms are available in 5-mm incremental sizes from 55 to 80 mm. They must remain in place for eight hours after intercourse and may be damaged by oil-based lubricants.

Method for fitting a diaphragm

Selecting a diaphragm may begin by inserting a 70-mm diaphragm (the average size) and then determining whether this size is correct or is too large or too small.

Another method is to estimate the appropriate size by placing a gloved hand in the vagina and using the index and middle fingers to measure the distance from the introitus to the cervix.

Oral contraceptives

Oral contraceptives have a failure rate of only 3 percent. OCPs have been associated with decreased risks of endometrial and ovarian cancers, benign breast disease, ectopic pregnancy and dysmenorrhea.

Combination oral contraceptives

Estrogen-progestin oral contraceptives act by inhibiting ovulation through suppression of gonadotropin secretion. Triphasic oral contraceptives decrease the incidence of progestin-related side effects and breakthrough bleeding.

Second-generation oral contraceptives contain norgestimate or levonorgestrel as the progestin. Third-generation agents contain desogestrel or gestodene as the progestin. Estrostep is a lower-dose estrogen preparation with varying amounts of estrogen.

Androgenic effects attributable to progestin include hair growth, male-pattern baldness, nausea and acne. If such side effects develop, a switch to a second- or third-generation agent with lower androgenic potential may resolve these problems. Women who experience nausea may benefit from taking the medication at night.

Hypertension, usually less than 5 mm Hg, may occur in some patients. If significant hypertension develops, a lower dose of progestin may be tried.

Weight gain may be countered by switching to a different formulation.

Administration issues

If started during the first five days of the menstrual cycle, oral contraceptives are effective throughout the first cycle of use. The medication should be taken at the same time each day.

Amenorrhea may occur with long-term use. Administration of an agent with higher estrogen or lower progestin activity may resolve this problem. A missed menstrual period indicates a need for a pregnancy test.

Breakthrough bleeding often occurs during the first three months of use. If breakthrough bleeding is a problem, a higher-dose progestin or estrogen agent may be tried. Agents that contain norgestrel are associated with low rates of breakthrough bleeding.

If a woman misses an oral contraceptive dose, she should take the dose as soon as she remembers it or take two doses the next day and then continue administration of the remainder of the monthly pack as usual. If two doses are missed during the first two weeks of the cycle, two doses per day should be taken for two days, and an additional form of contraception should be used for one week. The remainder of the pack should be administered as usual. If two or more doses are missed during the third week, the pack should be discarded, a new pack should be started, and an additional contraceptive method should be used for one week.

Progestin-only agents

Progestin-only agents are slightly less effective than combination oral contraceptives. They have failure rates of 0.5 percent compared with the 0.1 percent rate with combination oral contraceptives.

Progestin-only oral contraceptives ( Micronor, Nor-QD, Ovrette) provide a useful alternative in women who cannot take estrogen and those over age 40. Progestin-only contraception is recommended for nursing mothers. Milk production is unaffected by use of progestin-only agents.

If the usual time of ingestion is delayed for more than three hours, an alternative form of birth control should be used for the following 48 hours. Because progestin-only agents are taken continuously, without hormone-free periods, menses may be irregular, infrequent or absent.

Medroxyprogesterone acetate injections

Depot medroxyprogesterone acetate ( Depo-Provera) is an injectable progestin. A 150-mg dose provides 12 weeks of contraception. However, an effective level of contraception is maintained for 14 weeks after an injection. After discontinuation of the injections, resumption of ovulation requires nine months.

Every 12 weeks, the medication is given IM. An injection should be administered within five days after the onset of menses or after proof of a negative pregnancy test. Medroxyprogesterone may be administered immediately after childbirth.

Medroxyprogesterone injections are a good choice for patients, such as adolescents, who have difficulty remembering to take their oral contraceptive or who have a tendency to use other methods inconsistently. Medroxyprogesterone may also be a useful choice for women who have contraindications to estrogen. This method should not be used for women who desire a rapid return to fertility after discontinuing contraception.

Contraindications and side effects

Breakthrough bleeding is common during the first few months of use. Most women experience regular bleeding or amenorrhea within six months after the first injection. If breakthrough bleeding persists beyond this period, nonsteroidal anti-inflammatory agents, combination oral contraceptives or a 10- to 21-day course of oral estrogen may eliminate the problem. About 50% of women who have received the injections for one year experience amenorrhea.

Side effects include weight gain, headache and dizziness.

Levonorgestrel contraceptive implant ( Norplant) is effective for 5 years and consists of six flexible Silastic capsules. Adequate serum levels are obtained within 24 hours after implantation.

Emergency contraception

Emergency contraception may be considered for a patient who reports a contraceptive failure, such as condom breakage, or other circumstances of unprotected sexual intercourse, such as a sexual assault. If menstruation does not occur within 21 days, a pregnancy test should be performed.

Emergency contraception is effective for up to 72 hours after intercourse.

The major side effect of emergency contraception with oral contraceptives is nausea, which occurs in 50% of women; vomiting occurs in 20%. If the patient vomits within two hours after ingesting a dose, the dose should be repeated. An antiemetic, such as phenothiazine (Compazine), 5-10 mg PO, or trimethobenzamide (Tigan), 100-250 mg, may be taken one hour before administration of the contraceptive.

Intrauterine devices

IUDs represent the most commonly used method of reversible contraception worldwide. The Progestasert IUD releases progesterone and must be replaced every 12 months. The Copper-T IUD is a copper-containing device which may be used for 10 years.

IUDs act by causing a localized foreign-body inflammatory reaction that inhibits implantation of the ovum. An IUD may be a good choice for parous women who are in a monogamous relationship and do not have dysmenorrhea.

Contraindications include omen who are at high risk for STDs and those who have a history of pelvic inflammatory disease, and women at high risk for endocarditis. Oral administration of doxycycline, 200 mg, or azithromycin (Zithromax), 500 mg, one hour before insertion reduces the incidence of insertion-related infections.

RU486 ( mifepristone)

RU486 is an abortifacient, which is a competitive inhibitor of progesterone. The drug is most effective when taken early in pregnancy.

Dosage is 600 mg (three 200 mg tablets). The addition of misoprostol (Cytotec) 400 mg PO, 35-48 hours after RU 486, increases efficacy to 90-100%.

Patient management consists of a pretreatment pregnancy test, vaginal ultrasound for gestational age, hematocrit, and Rh type.

Confirmation that pregnancy has ended requires a repeat pregnancy test or vaginal ultrasound. §