Contraception

Contraception and Sterilization

In the past 15 years several new contraceptive op-I tions have been introduced in the United States,and several that were available have left the mar-ket for various reasons. Many methods are very reliable, although no method is effective if it is not used correctly. The goal of all contraception is obviously to prevent the sperm and oocyte from uniting. This goal is accomplished by severalmechanisms of action: (1) inhibiting the development and release of the egg (via oral contraceptives, long-acting pro-gesterone injection, or contraceptive patch and ring), or imposing a mechanical, chemical, or temporal barrier between sperm and egg (via condom, diaphragm, sper-micide, natural family planning, and intrauterine contracep-tion). As a secondary mechanism, some methods also alter the ability of the fertilized egg to implant and grow (e.g., intrauterine contraception and postcoital oral contracep-tives). Each approach may be used, individually or in com-bination, to prevent pregnancy, and each method has its own advantages and disadvantages, risks, and benefits.

Before advising a woman or couple on contraceptive options, the physician must understand the physiologic or pharmacologic mechanism of action, the effectiveness, the indications and contraindications, complications, and advantages and disadvantages of the contraceptive methods available, as well as the cultural context of the person or per-sons desiring contraception. When comparing methods, both the method failure rate (the failure rate inherent in the method if the patient uses it correctly 100% of the time) and the typical failure rate (the failure rate seen as the method is actually used by patients, that is, factoring in the mistakes in usage everyone will make from time to time, and even actual noncompliance) should be consid-ered, as described in Table 24.1.