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Millions of women in the United States use some type of hormonal contraception: combination oral contraceptive pills (OCPs), progestin-only pills, medroxyprogesterone acetate injections, or subdermal levonorgestrel implants. Abnormal uterine bleeding is a common but rarely dangerous side effect of hormonal contraception. It is, however, a major cause for the discontinuation of hormonal contraception and the resultant occurrence of unplanned pregnancy. The evaluation of abnormal uterine bleeding in women who are using hormonal contraception includes an assessment of compliance, a thorough history and complete physical examination to exclude organic causes of bleeding, and a targeted laboratory evaluation. Pregnancy and the misuse of OCPs are frequent causes of abnormal uterine bleeding. Bleeding is common during the first three months of OCP use; counseling and reassurance are adequate during this time period. If bleeding persists beyond three months, it can be treated with supplemental estrogen and/or a nonsteroidal anti-inflammatory drug (NSAID). Other options are to change to an OCP with a higher estrogen content or to a different formulation (i.e., a low-dose OCP containing a different progestin). Management strategies for women with abnormal uterine bleeding who are using progestin-only contraceptive methods include counseling and reassurance, as well as the administration of supplemental estrogen and/or an NSAID during bleeding episodes. (Am Fam Physician 2002;65:2073-80.2083. Copyright(c) 2002 American Academy of Family Physicians.)
Abnormal uterine bleeding is a common side effect of all forms of hormonal contraception. Although this bleeding is rarely dangerous, many women find it worrisome. In fact, women frequently discontinue hormonal contraception because of irregular bleeding and other side effects.1-3 One study4 found that 32 percent of 1,657 women who started taking oral contraceptive pills (OCPs) discontinued them within six months; 46 percent of the discontinuations were due to side effects.
Most women who discontinue hormonal contraception do not use another contraceptive method and are therefore at high risk for unintended pregnancy. An estimated one third of the 3 million unintended pregnancies in the United States each year are related to the misuse or discontinuation of OCPs.5
Mechanisms of Action
COMBINATION ORAL CONTRACEPTIVE PILLS
Most combination OCPs contain ethinyl estradiol (20 to 50 mcg) and a synthetic progestin (e.g., norgestrel, norethindrone, levonorgestrel, desogestrel). These pills inhibit ovulation in most women. They also induce thickening of the...