Sunday, October 14, 2007

Barrier methods of birth control

INTRODUCTION — Barrier methods of birth control physically block or otherwise prevent sperm from entering the uterus and reaching the egg for fertilization. Barrier contraceptives include the condom, diaphragm, and cervical cap. These methods: Have fewer side effects than hormonal contraceptives Offer effective protection against certain sexually transmitted diseases (STDs) Are available without a prescription (condom and spermicides)

Spermicides (contraceptive creams or gels) are chemical substances that destroy sperm. They are available over the counter and are typically recommended in combination with barrier contraceptives to maximize the contraceptive effect (see "Spermicide" below).

This topic discusses barrier methods of birth control, including the condom, diaphragm, cervical cap, Lea contraceptive, sponge, and spermicides. A discussion of hormonal and long-term birth control methods are available separately. (See "Patient information: Hormonal methods of birth control" and see "Patient information: Long-term methods of birth control"). An overview of all birth control methods is also available. (See "Patient information: Contraception").

CHOOSING A METHOD — It can be difficult to decide which birth control method is best due to the variety of options available. The best method is one that will be used consistently, is acceptable to the woman and her partner, and which does no cause bothersome side effects. Other factors to consider include: Efficacy Convenience Duration of action Reversibility and time to return of fertility Effect on uterine bleeding Frequency of side effects and adverse events Affordability Protection against sexually transmitted diseases

No method of contraception is perfect. Each woman must balance the advantages of each method against the disadvantages and decide which method she prefers. A list of questions that are useful for defining a person's preferences are provided in the table (show table 1).

EMERGENCY CONTRACEPTION — Emergency contraception (EC, also known as postcoital contraception or the morning-after pill) refers to the use of drugs to prevent pregnancy in women who have had recent unprotected intercourse (including sexual assault), or who have had a failure of another method of contraception (eg, broken condom). As many as 30 percent of women will become pregnant after a single unprotected act of sex that occurs near the time of ovulation. Use of EC significantly reduces the chance of pregnancy, although pregnancy may still occur.

Experts are uncertain about how EC prevents pregnancy. Since these drugs are taken within hours of intercourse and implantation does not occur until approximately five to seven days after ovulation, use of EC does not interrupt pregnancy (medically, a woman is considered pregnant once a conceptus has implanted; however, some consider pregnancy to begin at conception).

Several options are available for EC (show table 2 and show table 3). Plan B is a pill pack that contains two 0.75 mg tablets of levonorgestrel, both of which should be taken as soon as possible after unprotected sex. It is also acceptable to take one pill as soon as possible, followed by the second pill 12 hours later (this is the instruction given by the manufacturer). The cost is approximately $40. The Plan B regimen is more effective and better tolerated than regimens using oral contraceptive pills that contain estrogen (eg, Ovral two tablets twelve hours apart or Lo/Ovral four tablets 12 hours apart).

Nausea and vomiting are the major side effects of the estrogen-containing regimen. A medication to reduce nausea and vomiting can be taken one hour before the first dose. Nausea and vomiting is less common with the levonorgestrel method. However, if levonorgestrel is vomited within one hour of taking it, a medication to prevent nausea can be taken, followed by a repeat of the EC dose.

EC is most effective when taken as soon as possible after intercourse. However, studies have shown that it is somewhat effective for up to 120 hours (five days) after intercourse, and may be started up to that time if necessary. After five days, insertion of a copper intrauterine device is considered the best way to prevent pregnancy. (See "Patient information: Long-term methods of birth control").

A risk of pregnancy still exists if the woman has unprotected intercourse after EC pills have been taken. Therefore, another method of contraception (eg, condoms) should be used for the rest of the cycle. A second dose of EC may be used if a second episode of unprotected intercourse occurs anytime after the first dose.

A woman who is sexually active and does not want to become pregnant can consider purchasing EC before it is needed. This would eliminate any delay in taking the first dose. In the United States, EC is approved as an over the counter medication for individuals (men or women) age 18 and older; proof of age is required (a government issued ID). Younger patients still require a prescription. Plan B is only available at sites with a licensed pharmacist.

A woman should have a menstrual period within three weeks of taking EC; failure to have a period may indicate pregnancy. An evaluation with a healthcare provider is recommended in this situation.

CONDOMS

Male condom — Male condoms are a thin, flexible sheath or cover that is placed over the penis to prevent semen from entering the partner's body during sexual intercourse. To help ensure optimal effectiveness and protection, people who use condoms must carefully follow instructions for their use.

Condoms are most effective when used with a vaginally-applied spermicide (see "Spermicide" below); use of the male condom and a vaginal spermicide is as effective as a hormonal method of contraception, and is more effective to prevent pregnancy than a condom alone (show table 4A-4B). However, spermicidal condoms (those that are packaged with spermicide applied to the condom) are no more effective and expire faster than condoms without spermicide.

When used properly, condoms can also reduce the risk of sexually transmitted infections such as HIV. Studies have found the following: There is a decreased risk of gonorrhea, chlamydia, trichomonas, syphilis, HIV, and HPV (human papillomavirus, which can cause genital warts and cervical cancer) in women whose male partner consistently uses condoms. (See "Patient information: Condyloma (genital warts) in women" and see "Patient information: Screening for cervical cancer" and see "Patient information: Testing for HIV"). In a study of HIV-negative women whose only risk for infection was a stable relationship with an HIV-infected man, none of the women who consistently used condoms became infected. Regular use of latex condoms appears to decrease the risk of HIV infection by about 69 percent.

Oil-based lubricants (eg, suntan oil, petroleum jelly, whipped cream) should not be used with latex condoms because this can cause breakage of the condom. Water-based lubricants are safe (eg, K-Y gel®, Astroglide®).

Most condoms are made of latex, which can be a problem for people who have an allergy or sensitivity to latex. Polyurethane condoms are available as an alternative to latex. Animal skin condoms (eg, lambskin) are not recommended when there is a risk of infection because they do not effectively prevent transmission of HIV.

Female condom — The female condom is worn by a woman to prevent semen from entering the vagina. It is a sheath made of polyurethane which is prelubricated with a silicone-based lubricant. There is a soft, flexible ring at each end. The edges of the ring at the closed end of the sheath are squeezed together and then inserted as far as possible into the vagina; upon release, the ring will open to hold the condom in place. The ring at the open end of the sheath remains outside the vulva, resting against the labia. The patient should check to make sure the condom is not twisted.

DIAPHRAGM/CERVICAL CAP — The diaphragm or cervical cap are placed over the cervix before intercouse. Pregnancy is prevented by blocking sperm from entering the uterus and killing sperm with the spermicide (see "Spermicide" below). Both require fitting by a trained clinician, and the fit should be checked after childbirth and weight loss or gain of more than 10 pounds (4.5 kilograms).

Both devices can decrease the risk of certain sexually transmitted diseases and infections, including gonorrhea, chlamydia, and pelvic inflammatory disease. However, the diaphragm and cervical cap are less effective than condoms in preventing the spread of HIV infection. Diaphragms and cervical caps are not recommended for women at high risk for HIV, who are HIV infected, or who have AIDS as they do not appear to prevent transmission of the virus.

In most studies, the failure rate (number of pregnancies) was higher for users of the diaphragm or cervical cap compared to hormonal methods of birth control (eg, the birth control pill) (show table 4A-4B).

Diaphragm — The diaphragm is a soft dome-shaped cup made of latex rubber or silicone with a flexible rim. Before intercourse, the hollow of the dome is partially filled with a spermicidal cream or jelly and then the diaphragm is inserted deep into the vagina and positioned so that it fits over the cervix (show picture 1). It must be left in place for six to eight hours after sexual intercourse, and then should be removed. If the woman has sex more than once during this time, an additional dose of spermicide should be inserted into the vagina.

Precautions — Most women can use the diaphragm; however; it is not a good method for those who have an allergy/sensitivity to latex, silicone, or spermicides; significant pelvic relaxation (uterine prolapse, cystocele, rectocele, poor vaginal tone); frequent urinary tract infections; HIV infection or are at high risk for acquiring HIV; or have difficulty with the insertion process. Women with a history of toxic shock syndrome should not use a diaphragm.

Cervical cap — The cervical cap is available in latex (the Prentif cap) or silicone rubber (FemCap) in multiple sizes. Similar to the diaphragm, it is partially filled with spermicide and placed over the cervix. It can remain in place for up to 48 hours.

OTHER BARRIER METHODS — There are several other barrier methods, none of which require a prescription. The Lea contraceptive and contraceptive sponge block sperm from entering the uterus and contain a spermicide to kill sperm.

Lea contraceptive — The Lea contraceptive is a pliable, cup-shaped silicone bowl with a one-way valve that allows for the passage of cervical discharge, menses, and air trapped behind the device during insertion. The vaginal walls keep it in place, which helps to provide a better fit. A silicone loop on the bowl eases insertion and removal.

The Lea can be inserted hours before intercourse and is left in place for at least eight and up to 48 hours afterwards, when it is removed and washed. As with the diaphragm, a spermicide is used with the device.

The Lea does not need to be fitted by a clinician (one size fits all) and is available without a prescription from a healthcare provider. Its effectiveness is comparable to that of the diaphragm (show table 4A-4B). It does not provide reliable protection from sexually transmitted infections.

Sponge — The Today sponge is a 2-inch wide circular disk that is 3/4 of an inch thick and attached to a loop that is used for removal. It contains a spermicide, and is moistened with tap water before insertion deep in the vagina.

The sponge can be left in place and used repeatedly for up to 24 hours. When compared to the diaphragm, the sponge was less effective (show table 4A-4B).

SPERMICIDE — Spermicides are chemical substances that destroy sperm. They are available in most pharmacies without a prescription. Spermicides are available in a variety of forms including gel, foam, cream, film, suppository, and tablet.

Spermicides may be used alone, but are more effective when used in combination with a condom, diaphragm, or cervical cap. Effectiveness is reduced if the patient does not wait long enough for the spermicide to disperse before having intercourse, if intercourse is delayed for more than one hour after administration, or if a repeat dose is not applied before each additional act of intercourse (show table 4A-4B).

Local irritation of the vagina is not uncommon with spermicide use, and spermicide-coated condoms are associated with an increased risk of urinary tract infection in the female partner. In the United States, the only spermicide available is nonoxynol-9; use of this spermicide alone is not effective in preventing transmission of sexually transmitted infections, including HIV.

WHERE TO GET MORE INFORMATION — Your healthcare provider is the best source of information for questions and concerns related to your medical problem. Because no two patients are exactly alike and recommendations can vary from one person to another, it is important to seek guidance from a provider who is familiar with your individual situation.

This discussion will be updated as needed every four months on our web site (www.patients.uptodate.com). Additional topics as well as selected discussions written for healthcare professionals are also available for those who would like more detailed information.

A number of web sites have information about medical problems and treatments, although it can be difficult to know which sites are reputable. Information provided by the National Institutes of Health, national medical societies and some other well-established organizations are often reliable sources of information, although the frequency with which they are updated is variable. National Library of Medicine

(www.nlm.nih.gov/medlineplus/healthtopics.html)
National Institute of Child Health and Human Development (NICHD)

Toll-free: (800) 370-2943
(www.nichd.nih.gov)
National Women's Health Resource Center (NWHRC)

Toll-free: (877) 986-9472
(www.healthywomen.org)
EngenderHealth

Phone: (212) 561-8000
(www.engenderhealth.org)
Planned Parenthood Federation of America

Phone: (212) 541-7800
(www.plannedparenthood.org)
The Hormone Foundation

(www.hormone.org)


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Use of UpToDate is subject to the Subscription and License Agreement. REFERENCES 1. Fu, H, Darroch, JE, Haas, T, Ranjit, N. Contraceptive failure rates: new estimates from the 1995 National Survey of Family Growth. Fam Plann Perspect 1999; 31:56.
2. Steiner, MJ, Dominik, R, Rountree, RW, et al. Contraceptive effectiveness of a polyurethane condom and a latex condom: A randomized controlled trial. Obstet Gynecol 2003; 101:539.
3. Gallo, MF, Grimes, DA, Schulz, KF. Non-latex versus latex male condoms for contraception. Cochrane Database Syst Rev 2003; :CD003550.
4. Gallo, MF, Grimes, DA, Schulz, KF. Cervical cap versus diaphragm for contraception. Cochrane Database Syst Rev 2002; :CD003551.
5. Kuyoh, MA, Toroitich-Ruto, C, Grimes, DA, et al. Sponge versus diaphragm for contraception. Cochrane Database Syst Rev 2002; :CD003172.

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