IUDs are the most cost-effective efficacious methods of contraception if used for at least two years.44 IUDs are the most widely used reversible contraceptive worldwide used by 12% of women. However, in the USA, fewer than 2% of women use IUDs, even though user satisfaction is greater than with any other contraceptive method. The two IUDs currently available in the USA, the copper-releasing ParaGard T 380A intrauterine contraceptive and levonorgestrel-releasing intrauterine system (IUS), are both T-shaped and have monofilament tails. They can be inserted at any time of the menstrual cycle. The copper variety may be used as an “emergency contraceptive method” if inserted within five days of unprotected intercourse. If used postpartum, it should be inserted within 7 minutes of delivery of the placenta or at 6–8 weeks. The copper IUD is effective for seven years. Its failure rate is 0.7% in the first year of use. The copper IUD impairs sperm motility and viability, disrupts oocyte division and the formation of fertilizable ova. Changes also occur in the endometrium that could interfere with the implantation of a fertilized ovum. Its primary disadvantage is an average 55% increase in monthly blood loss and dysmenorrhea.45 Both IUDs have efficacy rates comparable to sterilization. The levonorgestrel-releasing IUD is the most effective of the currently available IUDs. Its first-year failure rate is 0.1%. Progesterone-releasing IUDs thicken cervical mucus, impeding the movement of sperm. They inhibit sperm capacitation, survival and motility, suppress ovulation (in some women), thin and suppress the endometrium, and stimulate an inflammatory reaction that may impede sperm function and prevent implantation. It may affect tubal mobility and implantation. In addition to contraception, it can be used to treat menorrhagia, dysmenorrhea, and endometriosis. It can also be used for supplemental progesterone in women who take estrogen for hormone replacement therapy (HRT). Side effects While IUDs do not increase the risk of pelvic inflammatory disease (PID), this can occur within the first 20 days following insertion. The incidence of PID decreases from 7/700 within the first 20 days to 1/700 after 21 days. IUD users may acquire PID, either during the insertion process and/or from sexual activity. To decrease this risk, IUDs are generally not indicated if either the woman or her partner have multiple sexual partners and are therefore more likely to develop sexually related PID. The routine use of antibiotics administered orally one hour before insertion is not recommended.46,47 Even though antibiotic prophylaxis against subacute bacterial endocarditis is appropriate for women with valvular heart disease, prophylactic antibiotics are unnecessary for women with mitral valve prolapse. Actinomyces-like organisms are common in the genital tract. Symptomatic IUD users with positive actinomyces findings on a Pap smear should be treated with appropriate antibiotics and their IUD removed. Asymptomatic IUD users do not require IUD removal or antibiotic therapy. Complications also include uterine perforation and expulsion. Uterine perforation during insertion is rare. The expulsion rate is 2–7% within the first year. There is a higher risk of expulsion in nulliparous women and in women with severe dysmenorrhea or excessive blood flow. If a woman experiences expulsion, she has a 30% risk of having a second IUD expelled. Contrary to a widespread misperception, copper IUDs actually reduce the risk of ectopic pregnancy. In fact, the rate of ectopic pregnancy is 90% lower than in women who use no form of birth control. If a woman becomes pregnant while using the IUD, there is a 5% risk of an ectopic pregnancy. Any woman who conceives while using any method of contraception should be assumed to have an ectopic pregnancy until proven otherwise. A woman who conceives using the subdermal implant has a 17% chance of an ectopic pregnancy. A woman using a progestin-only OCP and who conceives has a 7% chance of an ectopic pregnancy, and a woman with tubal sterilization who conceives has a 33% chance (Figure 7.1).48 An IUD user who has an intrauterine pregnancy has a 50% risk of a spontaneous abortion. This risk can be reduced by the early removal of the IUD, if necessary under ultrasound guidance. Contraindications Nulliparity is not a contraindication to IUD use, although any potential IUD user should be counseled about the potential risk of PID and subsequent sterility. Parous women are not reported to have demonstrable changes in future fertility compared to users of other contraceptive methods; there are conflicting data in nulliparous women.49 Contraindications to IUD use are listed in Table 7.10. The levonorgestrel-releasing IUD can be used to treat menorrhagia and anemia and as an alternative to hysterectomy in women with bleeding.50 Follow-up Patients who do not practice safe sex are probably not good candidates for IUDs. If PID develops, the infection should be treated and the IUD should be removed if symptoms fail to improve within 72 hours after treatment begins. If a sexually transmitted infection (STI) is diagnosed, the infection should be treated but IUD removal is not necessary. If the patient cannot feel the IUD string and it cannot be visualized, pregnancy should be excluded. The clinician can probe for string presence in the cervical canal or a pelvic ultrasound can be used to evaluate whether the IUD is still present and within the uterine cavity.
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