Бар'єрні та інші перикоітальні контрацептиви

Condom use reliably reduces the risk of sexually transmitted infections (STIs), including HIV infection. Condoms may be made of latex, polyisoprene, polyurethane, silicone rubber, or lamb intestine. Lamb-intestine condoms are impenetrable to sperm but not to many of the viruses that can cause serious infections (eg, HIV). Thus, latex and synthetic (polyurethane, polyisoprene, and silicone rubber) condoms are preferred. Condoms also protect against human papillomavirus (HPV), thus reducing the risk of precancerous cervical lesions.

The external (male) condom is the only reversible male contraceptive method other than withdrawal, which has higher contraceptive failure rates.

The male condom is applied before penetration; the tip is pinched shut and should extend about 1 cm beyond the penis to collect the ejaculate.

The internal (female) condom is a pouch with an inner and an outer ring; the inner ring is inserted into the vagina, and the outer ring remains outside and covers the perineum. The female condom should be placed no more than 8 hours before intercourse. The penis should be carefully guided through the external ring to make sure that the ejaculate is collected in the pouch.

For both types of condoms, care must be taken to avoid spilling condom contents when the penis is removed after intercourse. With the external condom, the penis should be withdrawn immediately after ejaculation while the condom’s rim is held firmly against the base of the penis; this precaution prevents the condom from slipping off and spilling semen. The larger ring of the internal condom should be twisted to prevent semen from spilling. Emergency contraception should be used if contents spill, the condom slips, or the condom breaks.

A new condom should be used for each episode of sexual intercourse.

Pregnancy rates at 1 year are

• External (male) condom: 2% with perfect use and 18% with typical use

• Internal (female) condom: 5% with perfect use and 21% with typical use

The diaphragm is a dome-shaped cup with a flexible rim that fits over the cervix and upper part and lateral wall of the vagina. They are used with a spermicide and, together, provide an effective barrier to sperm. Spermicide is applied to the diaphragm before insertion. After the first episode of sexual intercourse, additional spermicide should be inserted into the vagina before each subsequent act. Diaphragms can be washed and reused.

Conventional latex diaphragms are made in various sizes. They are fitted in a woman by a health care professional so that it is comfortable for her. After childbirth or a significant weight change, conventional diaphragms need to be refitted.

A single-size diaphragm (single-size contraceptive barrier device, or SILCS diaphragm) is made of silicone and considered to be one size fits most. It is softer and more durable than traditional latex diaphragms.

The diaphragm should remain in place for at least 6 to 8 hours but not more than 24 hours after intercourse.

Pregnancy rates with conventional latex diaphragms in the first year are approximately 6% with perfect use but about 12% with typical use. Pregnancy rates with the SILCS diaphragm are similar to conventional diaphragm (1).

Diaphragms were once widely used (one third of women in 1940), but by the 2000s, fewer than 1% of women in the United States were using them. This decline in use is largely due to the development of many other more effective and easy-to-use contraceptive methods.

The cervical cap is made of silicone and resembles the diaphragm but is smaller and more rigid.

A spermicidal cream or gel should always be used with a cervical cap. The cervical cap must be inserted before intercourse; it can be inserted 15 minutes to 40 hours beforehand. It should remain in place for at least 6 hours after intercourse and not more than 48 hours.

Pregnancy rates are 18% with typical use in the first year, 10 to 13% with perfect use; rates are higher among parous women because obtaining a secure fit after childbirth is difficult.

Only one cervical cap is available in the United States. It comes in 3 sizes (small, medium, large); size is chosen based on a woman's pregnancy history. A health care professional must write a prescription before the cervical cap can be used, but it does not require a custom fitting.

The contraceptive sponge acts as both a barrier device and a spermicidal agent. It can be inserted up to 24 hours before intercourse. It should be left in place for at least 6 hours after intercourse. Maximum wear time should not exceed 30 hours.

Pregnancy rates with typical use are 12% for nulliparous women and 24% for parous women.

Vaginal foams, creams, and suppositories contain agents that provide a chemical barrier to sperm by damaging sperm cell membranes and thus preventing fertilization. Most spermicides contain nonoxynol-9 and are available without a prescription. These products are similar in efficacy; overall, the pregnancy rate is 19% with perfect use and 28% with typical (ie, inconsistent) use.

Spermicides should be placed in the vagina at least 10 to 30 minutes and no more than 1 hour before sexual intercourse and reapplied before each episode of sexual intercourse.

Because their efficacy is limited, spermicides are often used with other barrier methods. Spermicides do not reliably protect against STIs. Also, spermicidal agents may cause vaginal irritation that increases the risk of HIV transmission. For this reason, condoms are no longer lubricated with the spermicide nonoxynol-9.

Contraceptive pH regulator vaginal gel changes the vaginal pH; this change incapacitates sperm and thus prevents fertilization. The gel contains primarily lactic and citric acids. The pregnancy rate is 7% with perfect use and 14% with typical use. Using other barrier methods with vaginal gel improves efficacy.

pH regulator vaginal gel should be placed in the vagina no more than 1 hour before sexual intercourse and reapplied before each episode of sexual intercourse. It does not reliably protect against STIs.

1. 1. Schwartz JL, Weiner DH, Lai JJ, et al: Contraceptive efficacy, safety, fit, and acceptability of a single-size diaphragm developed with end-user input. Obstet Gynecol 125 (4):895–903, 2015. doi: 10.1097/AOG.0000000000000721