Contraception, barrier methods of

The use of a device and/or a chemical to stop sperm reaching an ovum, preventing fertilization and pregnancy. Barrier methods also help prevent the sexual transmission of diseases such as AIDS, genital herpes (see herpes, genital), and viral hepatitis (see hepatitis, viral). The male condom is one of the most widely used barrier contraceptives. Female condoms (see condom, female) are similar to, but larger than, male condoms. Other female barrier methods include the diaphragm (see diaphragm, contraceptive), a hemispherical dome of thin rubber with a metal spring in the rim to hold it in place against the vaginal wall, blocking the entrance to the cervix. It is used with a spermicide. A cervical cap (see cap, cervical) is an alternative to the diaphragm. The contraceptive sponge, which is a disposable, circular, polyurethane foam sponge impregnated with spermicide, is inserted high in the vagina and left in place for at least 6 hours after intercourse. Spermicides, in the form of aerosol foams, creams, gels, and pessaries, are placed in the vagina as close as possible to the cervix shortly before intercourse. Some spermicides should not be used with rubber barrier devices. Mechanical and chemical means used together correctly can be highly effective in preventing conception.