Patricia A. Lohr
Intrauterine contraception (IUC) is the most effective form of reversible birth control available yet it remains tremendously underutilized. Among women aged 15 to 44 only 1.3% use IUC (Mosher et al., 2004). In comparison, 18% of women in Scandinavian countries, 20% of Mexican women, and 40% of women in China choose IUC (Hubacher et al., 2001; Trieman et al., 1995). The low usage of IUC in the United States can be attributed to a lack of knowledge and unfavorable attitudes toward IUC (Forrest, 1996; Stanwood and Bradley, 2005), as well as widespread misperceptions about associated risks of genital tract infection and subsequent infertility. The latter raises concerns about recommending IUC to adolescents, which is reflected in the percentage of 15- to 19-year olds in the United States who use IUC (0.1%). Current thinking regarding recommendations for potential IUC candidates is evolving as more research becomes available on the use of IUC in nulliparous women, including adolescents, and as the relationship between IUC and pelvic inflammatory disease (PID) is better understood. Given the continued high rate of unintended pregnancies and abortions among adolescents, IUC represents a method that, if appropriately utilized, could substantially aid in their reduction (Wildemeersch, 2001).
Two IUCs are currently available in the United States—the copper-bearing T-380A intrauterine contraceptive device (IUD) and the levonorgestrel-releasing intrauterine contraceptive system (IUS). They share efficacy but differ in their side effects and labeling recommendations.
Candidates for IUC are multiparous and nulliparous women who desire long-term reversible contraception. IUC offers effectiveness and convenience comparable to sterilization and is considerably more cost-effective. Estimates are that every copper T-380A IUD used for 5 years saves the health care system $14,122 (Trussell et al., 1995). It is important to note that IUC candidates need not have completed their families; IUC is an excellent interval method. The IUS may also be an ideal method for young women with menstrual problems such as menorrhagia or dysmenorrhea. IUC may also be ideal for women with medical problems such as diabetes or hypertension. Selection of which IUC to use should be individualized to maximize the benefits achieved.
Most women are candidates for IUC, however there are restrictions, some of which are device specific. In general, the following conditions contraindicate IUC use (American College of Obstetricians and Gynecologists, 2005):
Nulliparity has never been a contraindication to IUC; however, nulliparous women require careful counseling. The woman needs to understand that her fertility is untested, and that she may experience difficulty conceiving after removal that is not related to IUC. In addition, the expulsion rate for nulliparous women may be higher than for parous women. Counseling should include the signs and symptoms, indicating that the woman may be expelling the device.
Common Misconceptions about Intrauterine Contraception
Issues Regarding Pelvic Infection
Studies in the 1970s and 1980s linked Dalkon shield use to an increased risk of PID. Over time, the long-term consequences of PID, such as ectopic pregnancy, infertility, and pelvic pain were also observed in women who had used the Dalkon shield. Because the Dalkon shield dominated the IUC market in those days, all IUCs were initially implicated. Further analysis, however, revealed that there were methodological flaws in many early observational studies (Grimes, 2000). The design of the device, the user, and the insertion technique are the most important factors to consider when assessing the risk of PID with IUC.
The Dalkon shield had a polyfilament tail that allowed pathogens from the vagina to ascend into the upper genital tract by a wicking action (Tatum et al., 1975). Modern
IUCs, which have monofilament tails, do not facilitate such infection (Ebi et al., 1996). IUC users who were at risk for STDs were found to be more likely to have upper tract involvement, but monogamous IUC users faced no increase in their long-term risk for PID (Cramer et al., 1985; Daling et al., 1985). It is important to note that there is a transient increase in infection immediately after insertion. This risk is generally limited to the first 20 days of use and results from endometrial contamination during IUC insertion (Farley et al., 1992).
The risk of PID with contemporary IUC is extremely rare (1 in 1,000) (Skjeldestat et al., 1996; Walsh et al., 1998). However, the potential for infection underscores the need to carefully evaluate the patient for possible cervicitis and to meticulously use sterile insertion techniques. Routine antibiotic prophylaxis for insertion is not warranted (Grimes and Schulz, 1999). The American Heart Association does not recommend spontaneous bacterial endocarditis prophylaxis at the time of IUC insertion or removal in the absence of infection (Dajani et al., 1997).
Actinomyces israelii is a gram-positive anaerobic bacterium normally found in the human gastrointestinal tract and is likely a component of female genital tract flora (Persson and Holmberg, 1984). Colonization with Actinomyces appears to increase with duration of IUC use (Evans, 1993). However, the correlation between finding Actinomyces on a Pap smear in an asymptomatic IC user and the development of pelvic actinomycosis, a very rare but serious condition, is unclear (Lippes, 1999). Management of asymptomatic users of IUC withActinomyces on Pap test should be based on clinical judgment and includes expectant management, oral antibiotics, removal of the IUD, or both antibiotic use and IUD removal (American College of Obstetricians and Gynecologists, 2005).
Issues Regarding Ectopic Pregnancy
Both the copper T-380A IUD and the levonorgestrel IUS reduce a woman's risk of ectopic pregnancy compared with the risk faced by a woman not using birth control (Sivin, 1991; Sivin and Stern, 1994). The copper T-380A IUD and the levonorgestrel IUS have an ectopic pregnancy rate of 0 to 0.5 per 1,000 woman-years, compared with an ectopic pregnancy rate of 3.25 to 5.25 per 1,000 woman-years among women who do not use contraception. This protection is so dramatic that women with prior ectopic pregnancies are candidates for IUC, although product labeling of the levonorgestrel IUS discourages use in women with history of or risk factors for ectopic pregnancies.
Issues Regarding Fertility
IUC is a rapidly reversible birth control method and, as such, is an excellent contraceptive choice for appropriate candidates to use to space their children. In prospective controlled studies of copper IUD users, the fertility of women after IUD removal was shown to be comparable with that in the general population; within 48 months of IUD removal 91.5% of the nulligravid women and 95.7% of the gravid women had conceived. Wilson found that there was no difference in the first-year rates of fertility, ectopic pregnancy, miscarriage, or preterm delivery for women who asked to have IUDs removed in order to conceive compared with women who had IUDs removed because of complications (Wilson, 1989). Similar percentages of women discontinuing the levonorgestrel IUS were found to be pregnant when followed up for 1 year (Sivin et al., 1992).
Although implicated as a cause of tubal infertility in early studies, a more recent, large case–control study comparing nulligravid women with primary infertility with and without tubal occlusion and primigravid controls found no increased risk of tubal infertility among previous users of IUC (Hubacher et al., 2001). The only significant association was between antichlamydial antibodies and infertility.
Issues Regarding Mechanism of Action
The mechanisms of action for the various IUCs differ, and the details of each are described separately in later sections. However, it is important to note that IUC does not work by causing an abortion. Serial determinations of beta human chorionic gonadotropin (β-hCG) concentration obtained from users of IUC over several months failed to show the anticipated initial rise and fall characteristic of postimplantation (pregnancy) interruption (Segal et al., 1985). Interference with implantation is also highly unlikely, although a “hostile endometrial environment” is often offered as a mechanism of action. This hypothesis has been rejected because intrauterine flushing experiments failed to yield blastocysts. The most compelling direct experimental support for the contraceptive (prefertilization) action of IUC comes from tubal flushing/salpingectomy specimens, obtained from dozens of women undergoing sterilization procedures who had timed periovulatory intercourse. In the control group, 50% of the women not using contraception were found to have normally dividing fertilized ova indicative of successful fertilization. None of the IUC users had any normally dividing ova, which demonstrates the profound contraceptive action of IUC (Alvarez et al., 1988).
Lack of Knowledge about Intrauterine Contraception
A recent study of young pregnant women (age 14–25 years) revealed that only 50% had heard of IUC. Even those who had heard of it were not aware of its safety (71%) or efficacy (58%). Younger women were less likely to have information about IUC, highlighting the importance of teaching women about this highly effective method of contraception (Stanwood and Bradley, 2005).
Types of Intrauterine Contraceptive Devices
Two different designs of IUC are currently available in the United States—the copper T-380A IUD (ParaGard T-380A) and the levonorgestrel IUS (Mirena). Each provides effective and safe birth control, but each has sufficiently different individual characteristics to warrant separate discussion.
ParaGard Copper T-380A Intrauterine Device
Description of Device
The copper T-380A IUD is composed of a flexible T-shaped polyethylene frame whose
vertical stem is wrapped with a copper wire coil and whose horizontal arms are each encased in a collar of solid copper. The copper surface area totals 380 mm2. Monofilament strings are threaded through the bulb at the end of the stem. The stem contains barium sulfate to render it radiopaque. The U.S. Food and Drug Administration (FDA) has approved the copper T-380A IUD for 10 years of continuous use, but long-term studies show that it is quite effective for 12 years (UN Development Programme/United Nations Population Fund/World Health Organization/World Bank, Special Programme of Research, Development and Research Training in Human Reproduction, 1997). Insertion is relatively easy, but require training.
Candidates for IUD Use
In 2005, the FDA approved revisions to the prescribing label to explicitly include nulliparous women, women who are not in mutually monogamous relationships, and those with past history of PID. The list of potential users was also broadened to include women who are immunosuppressed (acquired immunodeficiency syndrome (AIDS), chemotherapy, corticosteroids). Current vaginitis and an abnormal Pap smear that is not suggestive of cervical or endometrial carcinoma were also removed as contraindications to use.
The IUD has traditionally been inserted during menses to exclude the possibility of pregnancy; however, it can be inserted at any time in the cycle if the patient is not pregnant. In fact, early expulsion rates can be halved if insertion is delayed until the end of menses (White et al., 1980). The use of local paracervical or intracervical anesthesia may be helpful in decreasing pain when insertions are performed in nulliparous women. Immediate insertion after an uncomplicated first trimester abortion is safe and effective (Grimes et al., 2004) although the practice is not common in the United States. Analysis shows that immediate postabortal insertion is estimated to result in 13 fewer pregnancies per 1,000 women compared to delayed insertion (Reeves et al., 2005). A new IUD can be placed immediately after the prior one has been removed if the patient is still an appropriate candidate. The labeling allows up to 10 years of use, but studies show that it is effective for at least 12 years (UN Development Programme/United Nations Population Fund/World Health Organization/World Bank, Special Programme of Research, Development and Research Training in Human Reproduction, 1997).
The typical first-year failure rate of the copper T-380A IUD is 0.8% (Trussell, 2004), the 10- and the 12-year cumulative failure rates are 2.7% and 2.2%, respectively (UN Development Programme/United Nations Population Fund/World Health Organization/World Bank, Special Programme of Research, Development and Research Training in Human Reproduction, 1997). The failure rate of the IUC is lower than the typical first-year failure rate with oral contraceptives, Depo Provera, the contraceptive ring, and contraceptive patch. It is also lower than the 10-year failure rates of many interval sterilization techniques used in young women (Peterson et al., 1996).
Mechanisms of Action
The copper released from the IUD interferes with sperm transport and capacitation (Zipper et al., 1971). Forward motility of sperm is markedly impaired and sperm head-tail disconnection is frequently observed (WHO Scientific Group, 1987). The inflammatory reaction in the endometrium induced by the foreign body is spermicidal (Sagiroglu, 1971). Copper ions that spread into the fallopian tubes also inhibit acrosomal enzyme activation. Without the acrosomal enzymes, the sperms are unable to penetrate the zona pellucida. Ova fertilizability is also reduced due to increased prostaglandin peritoneal levels, probably induced by copper. The best overall description of the mechanism of action of the copper T-380A IUD is that it is a “functional spermicide.”
The copper T-380A IUD should not be inserted if any of the previously listed contraindications exist (see page 615) or if the patient has (a) Wilson disease or known allergy to copper or (b) a uterine cavity <6 cm or >9 cm on uterine sounding.
counseling about the signs and symptoms of expulsion in the initial months after insertion.
Mirena Intrauterine System (Levonorgestrel Intrauterine System)
Description of Device
The levonorgestrel IUS is composed of a flexible T-shaped frame with a steroid reservoir surrounding its vertical stem. The reservoir consists of a cylinder made of a mixture of levonorgestrel and polydimethylsiloxane, which releases 20 µg of levonorgestrel per day. The polymer is mixed with barium sulfate, which renders it radiopaque. The unit is also visible ultrasonographically, but its appearance is subtler than that of the copper T-380A IUD. The levonorgestrel IUS has two monofilament tail strings, which are threaded through a bulb at the base of the T. With its arms open, the levonorgestrel IUS measures 32 mm in both the horizontal and vertical directions. The levonorgestrel IUS is approved for 5 years of use. It is recommended that insertion be performed during the first 5 days of menses to ensure that the levonorgestrel IUS will provide adequate first-cycle protection. The insertion technique for the levonorgestrel IUS is quite straightforward, but it differs significantly from that of other such devices and requires training.
The typical and perfect first-year failure rates for the levonorgestrel IUS are both 0.1% (Trussell, 2004). The cumulative 5-year failure rate found in various studies has ranged from 0.5% to 1.1%.
Mechanisms of Action
The levonorgestrel IUS prevents pregnancy primarily by exerting a very potent, continuous progestin effect on the cervical mucus to render it impenetrable to sperm. The IUS induces inflammatory changes in the endometrium, which are spermicidal. The progestin produces a thin, atrophic endometrium and slows tubal motility. The clinical significance of these last two progestin effects is not yet known. Systemic progestin levels are not sufficiently elevated to consistently suppress ovulation.
In addition to the general contraindications for IUC (see page 615), the levonorgestrel IUS is not intended for use in women who have allergic reactions to any of its ingredients. Menorrhagia is not a contraindication to the use of levonorgestrel IUS, because the levonorgestrel IUS significantly reduces monthly menstrual blood loss. In fact, in 98 of the 100 countries that have approved the levonorgestrel IUS, it is used to treat menorrhagia as a labeled indication (Irvine et al., 1998). Dysmenorrhea can also be reduced with the use of the levonorgestrel IUS and appears to be superior to combined oral contraceptives in reducing painful menstruation (Suhonon et al., 2004).
The advantages are similar to those of the copper T-380A IUD, except that the levonorgestrel IUS reduces menstrual loss and dysmenorrhea (Ronnerdag and Odlind, 1999; Suhonen et al., 2004). The levonorgestrel IUS may lower the risk of PID, but the data are not conclusive (Grimes, 2000). One small study found that levonorgestrel IUS users had an 85% lower incidence of Pap smears showing Actinomyces-like organisms, compared with users of a copper IUD (Merki-Feld et al., 2000).
The disadvantages are similar to those of the copper T-380A IUD. The levonorgestrel IUS cannot be used as a form of emergency contraception.
Use in Adolescents
Although the teen birth rate in the United States is declining, teen pregnancy remains higher in the United States than in any other industrialized country and the vast majority
of these pregnancies are unintended (Abma et al., 2004). The reduction in the number of adolescent pregnancies has been attributed in large part to the use of long-acting contraceptive methods that circumvent inconsistent use by avoiding daily method adherence. Adolescents who experience a pregnancy are at particularly high risk of unintended repeat pregnancy (Maynard and Rangaranhan, 1994). The need for highly effective, safe, long-acting birth control for adolescents at risk of pregnancy can be met by IUC for select teens.
The use of IUC in adolescents and nulliparous women is not new. Early studies on interval and immediate postabortal insertion of IUC in adolescents found high continuation and low complication rates (Goldman et al., 1979; Edwards et al., 1974; Roy et al., 1974). Recent data on the levonorgestrel IUS suggest that it is a very acceptable method (Otero-Flores et al., 2003; Suhonen et al., 2004). Diaz et al. (1993) compared the clinical performance of 995 parous adolescents using a copper T-380A IUD with a cohort of paired controls 10 years older of the same parity. Although the rates for pregnancy, expulsion, and removal were higher in adolescents, the ranges were within those reported in the literature for IUC. Removals due to infection were few, and the rate was not significantly different from that for older women. Overall, the performance was similar or better than other reversible methods in this age-group. Therefore, in the appropriate adolescent or young adult, IUC should be considered along with other methods. Selection of the appropriate device should be tailored to individual needs.
Pregnancy with Intrauterine Contraception in Place
Pregnancies in current users of IUC are rare. The location of the pregnancy should be determined as early as possible, because 8% of pregnancies that occur with the copper T-380A IUD and 50% of pregnancies with the levonorgestrel IUS are ectopic. It is recommended that the device be removed in the first trimester of an intrauterine gestation if the strings are visible in the vagina because of the risk of spontaneous or septic abortion. Although the loss rate may be higher if IUC is retained, no IUC-related deaths among pregnant women in the United States have been reported. First trimester removal reduces the risk of spontaneous abortion by approximately 50%. Late in pregnancy, the strings are rarely visible unless the placenta is low-lying, and there is no demonstrated benefit to IUC removal at this time. If the strings are not visible, it is prudent to obtain an ultrasound study, because the most common reason for pregnancy is a previously undetected expulsion. If the device is present, there is no reason to remove it. The risk of birth defects is not increased, but the patient should be alerted to signs and symptoms of preterm labor, because an increased risk of premature birth has been demonstrated. If a teen elects to abort the pregnancy, the device can be removed at the time of the procedure.
Several smaller copper IUDs as well as a “frameless” IUD specifically designed for nulliparous women have been studied in Europe, Asia, and Latin America. These devices appear to have lower expulsion rates and greater acceptability than the copper T-380A IUD (Duenas et al., 1996; Otero-Flores et al., 2003; Wildemeersch et al., 2003). A small intracervical levonorgestrel-releasing device has also been developed and appears to be equal in efficacy to the levonorgestrel IUS (Pakarinen and Luukkainen, 2005).
Guidelines for Patients
The following is a suggested format for informing teens about IUC.
IUC is a small plastic device that is placed in the uterus (womb).
IUC is inserted in the doctor's office. It does not require surgery but sometimes a local anesthetic is used to numb the cervix (the opening to the uterus) and make inserting IUC more comfortable.
IUC appears to work primarily by preventing fertilization of an egg by sperm. The copper in the ParaGard IUD probably has an antisperm effect, and the hormones in the medicated IUS blocks sperm from entering the womb.
In the United States currently, there are two types of IUC available. One contains copper, and the other contains the hormone levonorgestrel. Both are shaped like the letter T and are approximately 11/4 in. tall. Each has a thread or “tail” on the end, which allows the woman to check that the device is in place and also makes removal easier. The copper IUD is effective for up to 12 years. The levonorgestrel IUS can be used for up to 5 years.
IUC is the most effective form of reversible birth control. Both the copper T380-A IUD and the levonorgestrel IUS are more than 99% effective at preventing pregnancy in the first year of use.
With the copper T-380A IUD, the most common side effects are increased menstrual flow and cramps, which may be reduced by use of an over-the-counter pain medication such as ibuprofen. These side effects lessen after the first few months. With the levonorgestrel IUS, irregular spotting and bleeding are common in the first 3 to 6 months, but after that a woman's periods decrease dramatically and may stop altogether. Absence of a period is not dangerous and does not mean that the blood is “building up inside.” Rather, the lining of the uterus is so thin that there is very little or no tissue to be shed each month.
IUC is safe when used in the appropriate individuals. IUC should be used in women who are in relationships that do not put them at risk for STDs.
IUC is a safe, effective, easy-to-use, and cost-effective form of contraception. There is no need to remember to use the method every day or with every act of sex.
For Teenagers and Parents
http://www.plannedparenthood.org/pp2/portal/files/portal/medicalinfo/birthcontrol/pub-contraception-iud.xml. Planned Parenthood site on IUDs.
http://www.aafp.org/afp/981200ap/981200c.html. American Academy of Family Physicians handout on IUDs.
http://kidshealth.org/teen/sexual_health/contraception/contraception_iud.html. Teen site with explanation of IUDs.
For Health Care Providers
http://www.paragard.com/. Ortho-McNeil site for ParaGard T-380A IUD. In addition to educational materials, the Web site also includes information for providers and patients on assistance with reimbursement.
http://www.mirena.com/. Berlex site for Mirena.
https://www.arhp.org/healthcareproviders/cme/onlinecme/IUDCP/TOC.cfm. Association of Reproductive Health Professionals Web site for the 2004 “New Developments in Intrauterine Contraception” educational program.
http://www.aafp.org/afp/20050101/95.html. American Academy of Family Physicians, Insertion and Removal of IUDs.
http://www.archfoundation.com/. The ARCH foundation is a not-for-profit foundation established to assist low-income women who do not have insurance coverage for the Mirena® IUS.
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