Patricia A. Lohr
Spermicides are agents that kill sperms whereas barrier contraceptives block their movement toward the upper genital tract. Barrier contraceptives are available in a wide variety of designs, including the male and female condom, diaphragm, cervical cap, cervical shield, and sponge. Vaginal spermicides come in many forms such as foam, gel, cream, suppository, and film. In general, barrier methods and spermicides have higher failure rates but fewer systemic side effects than other modern contraceptive methods. Barrier methods also offer some reduction in the risk of sexually transmitted diseases (STDs). Many barrier contraceptives and all spermicides are available over the counter and improve adolescent access to birth control. The high typical-use failure rates of barrier methods and spermicides can be considerably lowered if they are used more consistently or in combination with other contraceptive methods.
Condoms (Fig. 45.1) are the oldest method of male contraception and the second most popular reversible form of birth control in the United States (Mosher et al., 2004). Since the mid-1980s, condom use among teenage males has been increasing. The most recent data from the 2002 National Survey of Family Growth (NSFG) shows a continuation in this trend; 71% of teenage males reported condom use at sexual debut and an equal percentage reported condom use during the last episode of sexual intercourse (Abma et al., 2004). Trends differed by ethnicity and gender. Non-Hispanic black teens were more likely than other groups to report condom use at first sex, and Hispanic males were more likely to report no contraceptive use. Female teens report lower rates of male condom use than male teens; however, the number using condoms is also increasing. The percentage of female teenagers using a condom during their most recent sexual activity increased from 38% in 1995 to 54% in 2002.
Consistent condom utilization remains a problem for teenagers. In 1998, fewer than half (45%) of sexually experienced adolescent men used condoms consistently (Sonenstein et al., 1998). According to the 2002 NSFG data, the percentage of teenage males who reported using a condom every time they had intercourse over the preceding 12-month period was only 37% (Abma et al., 2004).
Condoms are very cost-effective for episodic intercourse, which is often found among teens. For long-term use, however, the condom's higher failure rate drives its overall cost much higher.
The human immunodeficiency virus (HIV) epidemic has heightened public awareness and acceptance of condoms. A significant degree of STD protection is afforded by latex and polyurethane condoms, which are impermeable to Chlamydia trachomatis, Neisseria gonorrhoeae, herpes simplex virus, cytomegalovirus, hepatitis B virus, and human papillomavirus (HPV). Millions of women use condoms in conjunction with other methods (e.g., sterilization, birth control pills, or spermicides) to capture this STD risk reduction benefit. Seventeen percent of adolescents combine the male condom with a female method of contraception for STD risk reduction and/or enhanced contraceptive efficacy (Sonenstein et al., 1998;Abma et al., 2004).
Uses of Male Condoms
Types of Male Condoms
The more than 100 brands of condoms available in the United States provide a wide range of choices in size, shape, thickness, lubricant, and design features intended
to enhance sensation and utilization. Three materials are used in manufacturing condoms: latex, lamb cecum (used to make natural membrane or “skin” condoms), and polyurethane. Condoms made from other synthetic materials are in development and testing. Latex condoms dominate the market (99%), whereas natural membrane and polyurethane condoms account for <1%. Condoms are available in several sizes, but most condoms are 170 mm long and 50 mm wide. The thickness ranges from 0.03 to 0.10 mm. Condom shapes vary (straight-sided, baggy, or contoured), as do their textures (smooth or ribbed). One experimental nonlatex design, the eZ·on condom, is a baggy sheath that is slipped on like a sock rather than rolled on. Condoms are lubricated by a wide range of materials such as silicones, spermicides, and water-based gels. Other features that are intended to make condoms more pleasurable to use include an array of colors, scents, and tastes.
FIGURE 45.1 The male condom—patient information sheet.
Some latex condoms are available with a spermicidal coating of nonoxynol-9. Spermicides may provide lubrication, but they do not contribute to STD risk reduction (Roddy et al., 1998) and existing data is very limited to support an added improvement in preventing pregnancy.
Spermicides may cause genital irritation, potentially leading to increased STDs and urinary tract infections (Handley et al., 2002). The spermicidal coating also drastically reduces the shelf life of latex condoms, from an average of 5 to 2 years. The current recommendations of the Centers for Disease Control and Prevention state that use of nonoxynol-9 lubricated condoms is preferable to not using a condom. However, given the option, use of condoms with nonoxynol-9 is not advocated because of their increased cost, shorter shelf life, association urinary tract infections in young women, and lack of apparent benefit when compared with other lubricated condoms (Workowski and Levine, 2002).
Polyurethane male condoms are nonbiodegradable and require less fastidious handling before use. They are not susceptible to damage by petroleum-based lubricants, lack the latex allergens, and do not have the unexpected taste or smell, occasionally associated with latex condoms, during oral-genital contact. Polyurethane itself is a stronger material than latex, but it lacks elasticity. With the exception of the experimental eZ·on condom, pregnancy rates in clinical trials were not higher in polyurethane condom users, but the slippage and breakage rates for the polyurethane condoms were four to eight times higher than for a standard latex condom (Frezieres et al., 1998; Steiner et al., 2003). The
higher breakage and slippage rates of polyurethane condoms may diminish some of their protective effect against STDs. Polyurethane male condoms may best be reserved for couples who cannot tolerate latex products.
Natural “skin” condoms afford almost equal pregnancy protection as latex or polyurethane condoms, but do not reduce STD risks. They are also significantly more expensive which may be a barrier to use by teens.
Mechanism of Action
Condoms are sheaths made of latex (rubber-based), polyurethane, or processed lamb cecum which fit over the penis and block transmission of semen.
The male condom is the most effective barrier method available for pregnancy protection. The first-year failure rate for typical use of the latex male condom is 15%, and the failure rate for correct and consistent use is 2% (Trussell, 2004). Comparative trials of latex versus nonlatex condoms have confirmed higher breakage and slippage rates for nonlatex condoms during intercourse or withdrawal, but similar pregnancy rates (Gallo et al., 2003). Both latex and nonlatex condoms appear to have similar efficacy in preventing STDs. The most critical variable in predicting efficacy is consistent use, followed closely by proper technique. Condom quality has also improved dramatically in recent years. Research described in Consumer Reports found that 7 of 37 condom models failed routine testing in 1995, but by 1999 only 2 of 30 models failed those tests (Consumer's Union, 1995, 1999). The self-proclaimed “strength” and “contour” of the condom did not influence test scores.
Improving Condom Success
Dozens of excellent studies have been conducted to identify factors that predict consistent use of barrier methods, variables that would predict poor use, and ways to design interventions that might improve utilization. Most of this research has focused on the male condom. Given the vital role that barriers play in slowing the spread of STDs, answers to these questions are desperately needed. Unfortunately, studies show that solutions will not be easy to achieve.
There are profound differences in condom use by gender, with female adolescents reporting far less use of condoms than male adolescents (Brown et al., 1992; Ku et al., 1994; Abma et al., 2004). This may be due to the fact that female teens most commonly have older sexual partners and condom use by males tends to decrease with increasing age. Adolescent males appear to have greater knowledge about condom use and efficacy than females and may feel more comfortable obtaining condoms (Leland and Barth, 1992). Self-esteem may also play a role. Adolescent African-American females with higher self-esteem were found to be more likely to have positive attitudes toward condom use, feel more efficacious and less fearful about negotiating condom use, and perceived fewer barriers to using condoms (Salazar et al., 2005).
Many teens have misperceptions about condoms. Among 16,677 teens surveyed, approximately one third believed that condoms work just as well when Vaseline is used with them, and approximately one fifth believed that natural membrane condoms provide better protection against HIV than the latex condom (Crosby and Yarber, 2001). In addition, perception of knowledge about condoms among teens is not always associated with actual knowledge or use. In a longitudinal study of 404 virginal male adolescents who became sexually active during the study, those with low objective but high-perceived knowledge were approximately 3 times less likely to report using a condom at first intercourse (Rock et al., 2005).
Adolescents remain at high risk of STDs, particularly minority youth and young men who have sex with men (Centers for Disease Control and Prevention, 2003; Lightfoot et al., 2005). Youth who identify as bisexual appear to be at extremely high risk due to higher frequencies of multiple sexual partners, STDs, unprotected intercourse, and injection drug use (Goodenow et al., 2002). A perceived risk of STD or HIV infection is associated with higher condom use and also with intention to use condoms in the future (Brown et al., 1992;Donald et al., 1994; Orr and Langefeld, 1993). However, several studies show that many adolescents who are clearly at increased risk for STDs have little appreciation of their vulnerability (Rosenthal et al., 1994; O'Donnell et al., 1995). Teens with a history of a STD also do not appear to apply the factual knowledge gained from the prior experience to alter sexual behaviors, thereby providing an additional challenge to educational prevention efforts (DiClemente et al., 2002).
A common finding of virtually all studies is that condom use is increased when adolescents believe that their peers use condoms. Other factors that increase condom use are when teens believe that condoms can prevent STDs, when teens feel that they can talk to their partner about risks, when they have easy access to a supply of condoms, know how to use a condom, and carry condoms with them (Joffe and Radius, 1993; Schuster et al., 1998; DiIorio et al., 2001). Condom use is decreased when risky sexual behavior is just one of a cluster of risky health behaviors (e.g., smoking, substance abuse) or other lifestyle risks (e.g., violence). Substantial societal changes apparently are needed to address these issues. Putting condoms in open containers may be necessary to provide adolescent access to condoms, but it is clearly not sufficient to ensure their use.
For individual success in clinical practice, providers should be aware of condom misuse (Wood and Buckle, 1994) and should do the following:
Correctly place the condom. Judge which way the condom will unroll. Allow some slack at the top of condoms that have no reservoir tip; fit more snugly those with ejaculatory reservoirs once erection is complete. Squeeze the air out of the reservoir areas. Completely unroll the full length of the condom.
Side Effects of Male Condoms
Latex allergies are becoming more common in the United States; estimates are that latex allergies are found in 2% to 4% of couples using condoms. Among latex-exposed workers, the average may be as high as 18%. This number may be lower in the teen population with less previous exposure to latex. Polyurethane condoms are strongly recommended for latex-allergic couples, because the transition from mild reactions to anaphylaxis can develop rapidly. Some authors have suggested that the unsensitized partner could still use a latex condom if it is covered by a plastic condom. This strategy may reduce topical irritation, but the latex powder is a potent allergen and can induce severe, even life-threatening allergic reactions.
Condoms made of newer, nonlatex plastic materials, such as Tactylon, are in clinical trials and may be able to reduce the slippage and breakage problems associated with polyurethane (Callahan et al., 2000). A deproteinized latex condom (Manix Crystal) is available in France and other European countries and appears to be a safe alternative for latex-allergic individuals (Levy et al., 2001). Male condoms with new shapes (cap condoms) and different sized condoms (including snugger fit and custom-sized condoms) are increasingly available. The Unisex Condom, which can be used by either partner, is available in Canada and can be purchased through on-line condom distribution sites.
The only female condom currently available in the United States is the FC Female Condom (formerly known as the Reality condom; Fig. 45.2). The device is a thin polyurethane sheath measuring 17 cm in length and 7.8 cm in width. It contains flexible polyurethane rings at each end. The inner ring is loose within the sheath. At the time of insertion, the inner ring is pivoted parallel to the axis of the vagina and is used to introduce the device through the introitus to the vault, just as a diaphragm is placed. After insertion, the inner ring is rotated at the top of the vault to stabilize the device during intercourse. The outer ring, which is fixed to the base of the device, remains outside the vagina. The female condom provides a barrier along the length of vagina and partially covers the introitus. It is lined internally with a silicone-based “dry” lubricant and may be combined with vaginal spermicides. The female condom should never be used with the latex male condom, because each device can compromise the integrity of the other.
Far fewer adolescents use the female condom than the male condom; only 1.7% report ever using the female condom (Abma et al., 2004). As with the male condom, adolescents appear to use the female condom inconsistently, often choosing to use a male condom instead—even when supplied with female condoms (Marshall et al., 2002). Among female teens with experience using the female condom, more than half found it to be an acceptable method and a very low percentage (4%) reported that they did not use the female condom because of embarrassment.
The female condom underwent 6-month clinical efficacy trials, during which time a 12.5% failure rate was observed in typical use in the United States. This rate has been annualized to a typical first-year failure rate of 21% (Trussell, 2004). Perfect-use rates are considerably lower (5%), reflecting perhaps the difficulty users experienced with this method. The female condom is impermeable to HIV and comparative studies of male and female condoms have found similar protection against STDs (Drew et al., 1990; French et al., 2003).
Advantages and Disadvantages
The female condom is available over the counter in single-size disposable units (Fig. 45.2); they are considerably more expensive than the male condom. The female condom causes no known adverse physical side effects. The polyurethane is not sensitive to petroleum-based products. However, its use may be challenging; even users who are experienced with diaphragm insertion may find the female condom difficult to insert. The package instructions say that correct placement may be difficult in the first or second attempt because of the device's lubrication. The female condom may be inserted up to 8 hours before intercourse to permit a relaxed insertion. The consumer is warned not to tear the sheath with fingernails or other sharp objects. During intercourse, the penis should be manually guided into the device. The couple is to remain attentive throughout coitus to the position of the outer ring to ensure that it does not ride up or get pushed into the vagina. The male partner must avoid excessive friction between his penis and the device, which could increase the breakage rate or cause inversion of the device on withdrawal. Additional lubrication applied within the condom can help reduce this risk and also reduces the noise the device may make during intercourse.
The relative complexity of the device and its low typical efficacy rate make the female condom a second choice after the male latex or polyurethane condom. However, the female condom may make an important contribution for women whose partners refuse to use male condoms. For adolescents, extensive education and hands-on practice may be needed to ensure correct use of the female condom. Emergency contraception should be offered in advance to all female condom users.
Female condoms made of latex (which is less expensive than polyurethane) are currently in development and testing. Models available in other countries include the Reddy female condom, which is latex and uses a soft, polyurethane sponge to hold it in place inside the vagina, and the Natural Sensation Panty Condom that is shaped and worn like a woman's panty with a built-in condom.
The diaphragm (Fig. 45.3) is a dome-shaped latex device which, when introduced into the vagina, extends from the posterior fornix to the anterior vaginal wall to completely cover the cervix. The semirigid outer ring stabilizes the device in the upper vagina, and the dome holds spermicide directly against the cervix. As a mechanical barrier alone, the diaphragm has an unacceptably high failure rate; it is intended for use with contraceptive gel. The diaphragm must be professionally fitted and is available only by prescription.
Although not a commonly used method of contraception, there is a renewed interest in the diaphragm and other female barrier contraceptives that shield the cervix as a result of research indicating that they may be protective against the acquisition of HIV and other STDs (Moench et al., 2001). In addition, intensive research is being done to develop a vaginal microbicide (a topical product that protects against acquisition of HIV and other STDs) that may be used in conjunction with a diaphragm or similar vaginal device.
FIGURE 45.2 The female condom.
Types of Diaphragm
Diaphragms are available in sizes ranging from 50 to 105 mm in 5-mm increments and in four styles, which vary primarily by the construction of the rim or the seal.
FIGURE 45.3 Sample instruction sheet for diaphragms. (Courtesy of Teenage Health Center, Children's Hospital of Los Angeles, Los Angeles, California.)
Contraindications to Use
The typical-use failure rate varies between 16% and 18%. The failure use with correct and consistent use is estimated
to be 6%. Women who are more successful users of diaphragms are usually older, are comfortable touching their genitals, and are able to anticipate coitus. However, adolescents certainly can be taught to use diaphragms effectively (Fig. 45.3).
Tips to Improve Success of Method
Correct Fitting of Diaphragm
A diaphragm must be fitted properly to be effective. The diagonal length of the vaginal canal from the posterior aspect of the symphysis pubis to the posterior vaginal fornix is measured during the bimanual examination. The second and third fingers are inserted deeply into the vagina until the tip of the middle finger touches the posterior vaginal wall; then the point at which the index finger touches the symphysis pubis is marked with the thumb. The hand is withdrawn and the diaphragm is placed on the tip of the third finger with the opposite rim in front of the thumb to measure the correct size. This is a first approximation, which requires reconfirmation through actual fitting. The diaphragm is inserted and checked. Then the next larger size is fitted. The correct size is one size smaller than the first one perceived by the patient. For example, starting at size 60 and increasing the sizes until the patient perceives pressure with a size 70 would suggest that a size 65 would be appropriate for her. This is confirmed by examining the
patient with the diaphragm in place. The diaphragm should touch the lateral vaginal walls, cover the cervix, and fit snugly between the posterior vaginal fornix and behind the symphysis pubis. A diaphragm that is too large may buckle and permit sperm to bypass the diaphragm. A diaphragm that is too small may slip out of place. The health care provider should appreciate that the adolescent may be tense during initial fitting, causing the fitting of a smaller diaphragm than would be required if the adolescent were relaxed.
Patient education programs should include the following.
The SILCS intravaginal barrier is a one-size-fits-all diaphragm made of silicone that is entering phase II clinical trials. It is designed to be easier to use and intended for sale over the counter. The BufferGel Duet is a disposable, one-size-fits-all diaphragm made of dipped polyurethane that is in development. It will be marketed with prefilled BufferGel, a candidate microbicide and contraceptive.
Cervical Cap and Cervical Shield
The cervical cap and the cervical shield are cup-shaped devices made of silicone or latex, designed to cover the cervix and protect it from semen. Both are used with spermicide and provide contraceptive protection over multiple acts of intercourse for up to 48 hours without device removal. Each can be placed hours before coitus. The position should be reconfirmed before each coital act. The cap and the shield must be removed 48 hours after placement to reduce problems with odor and the possibility of toxic shock syndrome.
FIGURE 45.4 The FemCap. (Courtesy of FemCap, Inc., and Alfred Shihata, MD.)
The U.S. Food and Drug Administration (FDA) approved a silicone cervical cap, the FemCap, in 2003. It is shaped like a sailor's hat with a dome, rim, brim, and removal strap (Fig.45.4). The brim has a short side and long side, with the long side worn to the back of the vagina. The underside of the dome forms a bowl that covers the cervix. The brim forms a seal against the vaginal wall to hold the device in place. A small amount of spermicide is used in the bowl, spread on the outer brim, and placed in the groove between the dome and the brim. The FemCap comes in three sizes determined by the diameter of the inner rim. The smallest rim diameter (22 mm) is intended for nulliparous women, the medium (26 mm) cap is intended for women who have
been pregnant but have not had a vaginal delivery, and the largest (30 mm) is for women who have had a fullterm vaginal delivery. Although the sizing of the FemCap is determined by obstetric history, a clinician visit is required as the device can only be obtained with a prescription.
FIGURE 45.5 The Lea's Shield.
Lea's Shield is a reusable silicone cervical barrier that is held in place by its volume rather than its diameter (Fig. 45.5). The FDA approved it for use in 2002. The shield is oval in shape with a bowl that covers the cervix and fills the posterior fornix of the vagina, an anterior loop to aid in insertion and withdrawal, and a flat, tubular flutter valve leading from the inner surface of the bowl through to the convex side. This one-way valve prevents trapping of air between the cervix and the device after insertion and is intended to allow for egress of menstrual and other cervical secretions. Like the FemCap, the shield is held in place by the vaginal muscles rather than through suction. It is designed as a one-size-fits-all device but requires a clinician visit as it can only be obtained by prescription. The shield can be used with or without spermicide, although the addition of spermicide increases its contraceptive efficacy.
Contraindications for the cervical cap and shield include all those mentioned for the diaphragm. Cervical caps are not intended for use during menses. The shield may be used during menstruation, although none of the efficacy or safety trials included women who were menstruating.
The FemCap has been compared in a randomized trial with the diaphragm but was not found to be equivalent in efficacy (Mauck et al., 1999). Overall, the 6-month typical-use failure rate for the cap was 13.5% compared with 7.9% for diaphragm users. The differences between nulliparous and parous women in the FemCap group were not statistically significant (9.5% and 15.8%, p = 0.12). Extrapolating the 6-month unadjusted failure rate to 12 months gives a probability of 22.8 pregnancies per 100 women for the cap.
A 6-month efficacy trial of the Lea's Shield found a typical-use pregnancy rate of 8.7 per 100 women among those who used the device with spermicide (Mauck et al., 1996). There were no pregnancies among nulliparous women in this trial. The unadjusted typical-use failure rate for parous women was 11 per 100 women.
Fitting the Cervical Cap
Neither the FemCap nor Lea's Shield requires formal fitting, although a clinician visit is recommended to assure proper application and comfort with the devices.
Insertion of the FemCap
Removal of the FemCap
Insertion of Lea's Shield
Removal of Lea's Shield
After the introduction of the vaginal contraceptive sponge in 1983, it quickly became the leading female-controlled nonprescription contraceptive method. The manufacturer of sponges in the United States discontinued its production in early 1995 because the FDA found possible contamination along the production line, although the product was not compromised. The contraceptive sponge (Today Sponge) was brought back to the U.S. market in 2005.
The contraceptive sponge is made of pliable polyurethane foam that contains 1 gm of nonoxynol-9. A concave depression, or “dimple,” on one side fits against the cervix, and a woven polyester loop on the other side can be grasped for removal. After it is moistened with water, it is inserted into the vagina and is effective immediately. The sponge protects against pregnancy for 24 hours without the need to add spermicidal cream or jelly, regardless of the number of acts of intercourse. After intercourse the sponge must be left in place for 6 hours before is removed and discarded. Wearing the sponge for longer than 24 hours in not recommended because of the possible risk of toxic shock syndrome.
The sponge comes in one size and does not require fitting by a physician. It is relatively inexpensive ($10 for a package of three sponges) although the cost may be prohibitive for some adolescents. It is available without a prescription, can be inserted well before the onset of sexual activity, and is easy to use, making the contraceptive sponge well suited for adolescents.
Mechanism of Action
The primary contraceptive action of the sponge is provided by the spermicidal activity of nonoxynol-9, which is impregnated in the polyurethane foam. The sponge releases 125 to 150 mg of nonoxynol-9 slowly over a 24-hour period. The sponge also traps and absorbs semen and acts as a physical barrier between sperm and the cervical os.
The contraceptive sponge has different failure rates depending on the consistency of use and possibly parity. Overall, the typical-use failure rate of 16% in nulliparous women compared with 32% in parous women. Perfect use rates are 9% and 20%, respectively (Trussell, 2004). Observational data have suggested that parity may be less of a factor than motivation to use the sponge consistently when determining contraceptive efficacy of the sponge (Edelman and North, 1987).
Approximately 4% of users will experience a sensitivity reaction to the sponge that can lead to itching, burning, redness, or a rash. Although this may be due to nonoxynol-9, other components of the sponge such as the preservative may be the source of the sensitivity reaction.
Two contraceptive sponges, Protectaid and Pharmatex, are available in Canada and Europe and may eventually be brought to the United States. Clinical trials of an additional contraceptive sponge, Avert, are planned.
Vaginal spermicides are available in a wide array of delivery systems (Table 45.1). Spermicides can be used alone or in combination with barrier methods. They can play an important role in contraception for the adolescent, because they require neither a prescription nor a pelvic examination and are free from systemic side effects.
Spermicides have been shown to have bactericidal and virucidal activity in vitro, but clinical data in vivo have failed to demonstrate any reduction in the risk of STD acquisition. Several studies of spermicide use in high-risk women have found that nonoxynol-9 does not reduce the risk of HIV or other STD transmission. There is no clear evidence that the risk of seroconversion is increased by the use of spermicides, although one case–control study of commercial sex workers in Africa found that multiple uses daily (>3.5) may increase the risk of HIV transmission (World Health Organization, 2002). Eleven percent of heterosexual adolescent males report experience with anal intercourse (Gates and Sonenstein, 2000). Although little has been documented about lubricant use among heterosexual couples who practice anal intercourse, a large proportion of men who have sex with men use lubricants during rectal intercourse, and 41% choose products that contain nonoxynol-9 (Gross et al., 1998). Lavage and biopsy studies of rectal epithelium exposed to nonoxynol-9 have demonstrated rapid epithelial sloughing with exposure of the underlying submucosa (Phillips et al., 2004). Because this damage may increase the risk of transmission of STDs, including HIV, the use of nonoxynol-9–containing products during anal intercourse should be discouraged.
Types of Spermicides
The various spermicidal preparations differ in their onset and duration of action and mode of application. Table 45.1 displays the more commonly used types of spermicidal products as well as the differences in the concentration of nonoxynol-9 in each formulation. In general, each agent is active for approximately 1 hour unless used with a diaphragm, cap, or shield. Foam, which is the most commonly used agent, is instantly effective. Suppositories and film require 10 to 15 minutes to melt and distribute over the cervix. Each type of suppository comes with complete and appropriate patient instructions for use. Encourage patients to choose a spermicidal agent with a use pattern that will work well for them.
Nonoxynol-9 is the active agent in all spermicides available in the United States. In other countries, agents such as octoxynol and benzalkonium chloride are also available as spermicides. However, benzalkonium has been shown to be irritating to vaginal epithelial cells and to reduce lactobacillus counts (Patton et al., 1999).
Typical first-year failure rates for spermicides used alone are estimated to be as high as 29% (Trussell, 2004). A randomized trial comparing three spermicidal gels containing different doses of nonoxynol-9 (52.5 mg, 100 mg, and 150 mg) with a spermicidal film and suppository (both containing 100 mg of nonoxynol-9) found 6-month failure rates that ranged from 10% to 22% (Raymond et al., 2004). The pregnancy risk was statistically higher in the gel containing 52.5 mg of nonoxynol-9, but there was no difference between any of the formulations containing 100 mg of nonoxynol-9. Correct and consistent use of spermicidal agents is estimated to reduce the pregnancy rate to 18%. In the trial described, perfect-use probabilities ranged from 5.1% to 15.7%. When used in conjunction with other methods, such as barriers and emergency contraception, the pregnancy rate drops.
Mechanism of Action
The components of spermicidal agents include an inert base (foam, cream, or jelly), which holds the spermicidal agent and blocks sperm from entering the cervical os. Spermicides destroy sperm by breaking down the outer cell membrane.
The need for vaginal agents that are contraceptive and protective against HIV and other STDs is increasingly compelling. Much of current research and development activity is centered on developing an agent with these properties.
For Teenagers and Parents Condoms
http://www.plannedparenthood.org/birth-controlpregnancy/birth-control/condom.htm. Planned Parenthood information sheet on condoms.
http://kidshealth.org/teen/sexual_health/contraception/contraception.html. Teen oriented Web site with information on condoms and other birth control methods.
http://www.condomania.com/. Information site and selection site for different types of condoms.
http://www.siecus.org/pubs/fact/fact0011.html. Siecus information sheet on condoms.
http://www.youngwomenshealth.org/femalebarrier1.html. Information from Boston Children's Hospital on female condoms.
Diaphragms, Cervical Caps, Cervical Shields
http://www.plannedparenthood.org/utah/diaphragm.htm. Planned Parenthood information sheet on diaphragms.
http://www.mayoclinic.com/health/birth-control/BI99999/PAGE=BI00009. Information sheet on diaphragms, cervical caps, and cervical shields from the Mayo Foundation for Medical Education and Research.
http://www.femcap.com/index.htm. Product Web site for the FemCap.
http://www.leasshield.com/index.htm. Product Web site for Lea's Shield®.
http://www.mayoclinic.com/health/birth-control/BI99999/PAGE=BI00011. Information about the contraceptive sponge from the Mayo Foundation for Medical Education and Research.
http://www.todaysponge.com/. Product Web site with user and purchasing information.
http://www.sex-ed101.com/spermx.html. Sex Education 101 site with information on spermicides and many other issues.
http://www.fhi.org/en/. Family Health International Frequently Asked Questions on spermicides.
For Health Professionals
http://www.reproline.jhu.edu/english/1fp/1methods/1condom/condom.htm. Web site with presentation slides on condoms.
http://www.cervicalbarriers.org/. Informative Web site of The Cervical Barrier Advancement Society.
References and Additional Readings
Abma JC, Martinez GM, Mosher WD, et al. Teenagers in the United States: sexual activity, contraceptive use and childbearing, 2002. Vital Health Statistics, National Center for Health Statistics, 2004:23.
ACOG Committee Opinion. Condom availability for adolescents. Washington, DC: American College of Gynecologists and Obstetricians, 1995:154.
American Academy of Pediatrics. Condom availability for youth. Pediatrics 1995;95:281.
Brown LK, DiClemente RJ, Park T. Predictors of condom use in sexually active adolescents. J Adolesc Health 1992;13:651.
Callahan M, Mauck C, Taylor D, et al. Comparative evaluation of three Tactylon condoms and a latex condom during vaginal intercourse: breakage and slippage. Contraception2000;61:205.
Cates WC Jr. How much do condoms protect against sexually transmitted diseases. Int Plann Parenthood Fed Bull 1997;31:2.
Cates WC Jr, Holmes KK. Re: condom efficacy against gonorrhea and nongonococcal urethritis. Am J Epidemiol 1996;15:143.
Centers for Disease Control and Prevention. Trends in HIV-related sexual risk behaviors among high school students—selected U.S. cities, 1991–1997. JAMA 1999;282:228.
Centers for Disease Control and Prevention. Centers for Disease Control and Prevention: sexually transmitted disease surveillance, 2003. Atlanta, GA, U.S. Department of Health and Human Services, Centers for Disease Control and Prevention, 2003.
Consumer's Union. How reliable are condoms? Consum Rep 1995;60:320.
Consumer's Union. Condoms get better: tests of 30 models show far fewer failures than in past years. Consum Rep 1999;64:46.
Crosby RA, Yarber WL. Perceived versus actual knowledge about correct condom use among U.S. adolescents: results from a national study. J Adolesc Health Care 2001;28:415.
Davis KR, Weller SC. The effectiveness of condoms in reducing heterosexual transmission of HIV. Fam Plann Perspect 1999;31:272.
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