The Intrauterine Device: Still Misunderstood After All These Years

, Division of Maternal Health, Center for Maternal and Child Health, Maryland Department of Health and Mental Hygiene, Baltimore.

South Med J. 2000;93(9) 

In This Article


Recent studies have invalidated many previous misconceptions that have led to barriers in the general use of IUDs in the United States.

Pelvic Infections. A 1992 multicenter, multination World Health Organization (WHO) study clearly showed the risk of pelvic inflammatory infection (PID) to be primarily confined to the first 20 days after insertion.[17] In this study, Farley et al[17] found that out of almost 23,000 insertions, the rate of PID was 9.68 per 1,000 women years in the initial 20 days after insertion and 1.39 per 1,000 women years thereafter. After the initial 20 days, the incidence of PID remained low and constant. In 8 years, only 81 cases of PID were diagnosed among these 23,000 insertions. The higher rate of PID at insertion is most likely due to polymicrobial contamination of the uterus from the cervicovaginal flora at the time of insertion. Use of aseptic technique during insertion and minimizing the number of insertions is important in decreasing the risk of PID. Infections after the initial 20 days are thought to be due to acquired sexually transmitted diseases (STDs) and not the IUD itself. After purging the Dalkon Shield cases, a reanalysis of earlier data showed that women at low risk for infection (eg, married or cohabiting women with one sexual partner) were no more likely to have a pelvic infection than users of no contraception, even during the time of insertion.[18] Therefore, sexual behavior seems to be the most significant determinant of infection with IUD use.[19] Daling et al[20] and Cramer et al[21] also determined that women who had one sexual partner and who used the copper IUD had no increased risk of tubal infertility.

A large randomized control study of 1,867 women at 11 clinics in Los Angeles showed no difference in early IUD removal among 918 women given prophylactic antibiotics and 915 women given placebo.[22] More importantly, during the 90 days after insertion, the study detected only one case of salpingitis from each group. The study reaffirmed that in women at low risk for STDs, the incidence of IUD-associated PID is rare.

Liability. A 1990 survey of 395 obstetricians, gynecologists, and family practitioners in San Diego County revealed that fear of litigation was the most common barrier to prescribing IUDs.[23] However, most litigation related to IUDs in the past concerned product liability against the manufacturer -- not the clinician. The Planned Parenthood Risk Management group reported that only two claims (1% of total) between 1977 through 1988 were associated with IUD use and settled with unfavorable judgments.[24] Thus, concerns about IUD litigation among most clinicians are exaggerated.

Mechanism of Action. Both the American College of Obstetricians and Gynecologists and the WHO recognize that the copper IUD works primarily by prevention of fertilization and not prevention of implantation.[25,26] According to the WHO Scientific Group, "It is likely that the uterine and tubal fluids that are altered in the presence of an IUD impair the viability of the gametes, thus reducing their chances of union and impeding fertilization. Copper ions released by an IUD probably potentiate these effects."[26] In a landmark study of women about to undergo surgical sterilization, Alvarez et al[27] reported that no eggs were recovered from the body of the uterus within 132 hours after luteinizing hormone peak in any of 56 IUD users. Eggs were recovered in tubal flushings from 39% of IUD users (30% of copper IUD users) and 56% of control subjects. In this same study, 14 IUD users and 20 control subjects had coitus during the periovulatory period. None of the ova recovered from tubal flushings of the IUD users showed microscopic signs of normal fertilization, whereas 50% of the ova from control subjects did. Studies using highly sensitive assays for human chorionic gonadotropin reported fertilization in only 1 of 137 cycles among women using a copper IUD.[28] Copper seems to be especially toxic to sperm.[29,30] A recent comprehensive review of literature similarly states, "In Cu-IUD users, it is likely that few spermatozoa reach the distal segment of the fallopian tubes; those that encounter an egg may be in poor condition. Thus, the few eggs that are fertilized have little chance for development and their possibility for survival in the altered tubal milieu becomes worse as they approach the uterine cavity."[31]

Ectopic Pregnancy. The IUD protects women against ectopic pregnancy. In fact, women who use the copper IUD are 90% less likely to have an ectopic pregnancy than users of no contraceptive.[32] In 8,000 woman-years in randomized multicenter trials, only one ectopic pregnancy has been reported with the TCu380A.[32] The risk of ectopic pregnancy does not increase with duration of use.[33] Also, previous use of an IUD does not increase a woman's risk of ectopic pregnancy.[34] Because of such a protective effect against ectopic pregnancy, the TCu380A is an acceptable option for women with a history of ectopic pregnancy.

A 1998 survey of Maryland family practice (FP) and ob/gyn (OB) residents in their final 3 months of training revealed that 50% of FP residents and 20% of OB residents had done no IUD insertions during their training.[35] In addition, not one of the FP residents and only 20% of OB residents had done more than 10 IUD insertions during their training. This is similar to national results, which indicate that 66% of FP residents had never inserted an IUD and only 6% had managed ≥10 cases[36]; among OB residents, 38% had never inserted an IUD and 29% had managed ≥10 cases.[37] Providers not trained in IUD insertion will be less likely to recommend the IUD to their patients; conversely, with fewer women using the IUD, there will be less opportunity for training in IUD insertion for providers.

According to a recent survey, 16% of women hold a favorable attitude toward the IUD; however, among women who used the IUD, 99% reported being very or somewhat satisfied with the method -- the highest approval rate of any method surveyed.[38] Continuation rates for the IUD are among the highest for any reversible contraceptive method.[38]

Because of liability issues, IUDs available in other parts of the world have not made their way to the United States. One of these IUDs, the Levonorgestrel (LNg), has been available since 1990 and is approved in 10 countries. The LNg IUD delivers a progestin, levonorgestrel, to the uterine cavity and is as effective in prevention of intrauterine and ectopic pregnancy as copper IUDs.[39] Like the Progestasert, it causes less bleeding and pain. A distinct advantage of the LNg IUD, however, is that its duration of action is 5 years. Noncontraceptive benefits include possible control of menorrhagia from adenomyosis, myoma, and ovulatory dysfunction. It can also be used as the progestin component in hormone replacement therapy. Another European IUD is a frameless IUD (GyneFix), consisting of six copper sleeves on a surgical nylon thread.[40] The proximal end of the thread is knotted and placed in the fundal myometrium to anchor it.


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