INTRODUCTION — The intrauterine device (IUD) is the most used method of long-acting reversible contraception because of its high efficacy and safety, ease of use, and cost effectiveness. It provides a nonsurgical option for pregnancy prevention that is as effective as surgical sterilization. The most frequently used IUDs have a plastic frame and release either copper or a progestin to enhance the contraceptive action of the device.
Several terms are used to describe IUDs, including IUD and intrauterine contraception; the hormonal IUD or progestin-containing device is also referred to as an intrauterine system. In this topic, we use the term IUD for all types of IUDs.
This topic will discuss types of IUDs and their mechanism of action. Issues related to IUD selection, use in specific populations, removal, side effects, and complications are discussed separately:
●(See "Intrauterine contraception: Candidates and device selection".)
●(See "Intrauterine contraception: Insertion and removal".)
●(See "Intrauterine contraception: Management of side effects and complications".)
In this topic, when discussing study results, we will use the terms "woman/en" or "patient(s)" as they are used in the studies presented. We encourage the reader to consider the specific counseling and treatment needs of transgender and gender-expansive individuals.
BACKGROUND
Prevalence of use — The IUD is the most commonly used method of reversible contraception worldwide and is used by an average of 23 percent of female contraceptive users, with a range of <2 to >40 percent depending on the country [1,2]. In 2014, IUDs were used by 27 percent of female contraceptive users in Asia and 17 percent of female contraceptive users in Europe [2]. Use of IUDs has increased in the United States: Between 2002 and 2014, IUD use rose from 2 to 14 percent among United States women using contraception [3-7]. Actively informing women about benefits, risks, and common side effects of IUDs appears to improve consideration and acceptance of the method [8,9].
Types of IUDs — Two types of IUDs are available in the United States, copper containing and levonorgestrel (LNG) releasing:
●Copper IUD – The copper IUD is a T-shaped device which contains 380 mm2 copper (abbreviated copper 380 mm2, commercial name ParaGard) [10,11]. It is approved by the US Food and Drug Administration (FDA) for 10 years of use. There are other copper-containing IUDs, but none are currently FDA approved for use in the United States. (See 'Copper IUD' below.)
●LNG IUDs – The LNG IUDs are T-shaped devices that release LNG. There are four LNG IUDs available in the US which release a varying amount of LNG [12-15]. (See 'Levonorgestrel IUD' below.)
Multiple other IUD types and shapes have been used globally (picture 1).
Mechanism of action — IUDs prevent conception through multiple mechanisms (table 1); IUDs are not abortifacients [16-21]. Pregnancy appears to be prevented by a foreign body effect induced by the IUD frame and by local changes caused by the released medication. When the uterus is exposed to a foreign body, a sterile inflammatory reaction occurs, which is toxic to sperm and ova and impairs implantation [18,20,22-24]. The production of cytotoxic peptides and activation of enzymes lead to inhibition of sperm motility, reduced sperm capacitation and survival, and sperm phagocytosis which inhibit fertilization [25,26]. These cytotoxic effects are supported by studies in which fallopian tubes of IUD users were flushed but no sperm or fertilized ova were found [18,20]. Additional studies of IUD users were unable to find embryos or detect human chorionic gonadotropin, indicating that transient, or chemical, pregnancies were not occurring [23,27,28].
●Specific mechanisms by IUD type
•Copper IUD – The addition of copper provides further contraceptive benefits. Copper enhances the cytotoxic inflammatory response within the endometrium and prevents fertilization by impacting sperm migration, viability, and acrosomal reaction [17,23,24,29,30].
•LNG IUDs – The addition of LNG provides further contraceptive benefits. The progestin thickens cervical mucus, which acts as a barrier to the upper genital tract (ie, reduces sperm access to the upper tract and thereby prevents fertilization), causes endometrial decidualization and glandular atrophy, and may inhibit the binding of the sperm and egg by increasing glycodelin A production, which further impairs fertilization [31-33].
●Minimal impact on ovulation – Interruption of ovulation is not a major mechanism of IUDs. Copper IUDs have no impact on ovulation. For LNG IUDs, ovulation rates vary based upon the initial progestin dose and then increase as the progestin level falls over time. Most cycles are ovulatory. In clinical trials evaluating ovulation during the first year of IUD use, 45 percent of cycles were ovulatory for women using 52 mg LNG IUDs while 88 to 97 percent of cycles were ovulatory for lower-dose IUDs [12-15].
●Not an abortifacient – There is no evidence that IUDs disrupt an implanted pregnancy [34]. Despite the evidence that IUDs do not interrupt pregnancy (ie, are not an abortifacient), a 2019 survey of 893 US physicians reported that 17 percent believed that IUDs caused abortion [35].
Benefits — There are multiple benefits of IUD use for women including:
●Highly effective pregnancy prevention (>99 percent) (figure 1).
●Does not require regular adherence from user to maintain high effectiveness.
●Long acting.
●Rapidly reversible.
●Few medical contraindications for most women, including teens and nulliparous women. (See "Intrauterine contraception: Candidates and device selection", section on 'Contraindications'.)
●Few side effects.
●Private and does not interfere with the spontaneity of sex.
●Avoidance of exogenous estrogen (both IUD types) and hormones (copper IUD only).
●Reduced costs with long-term use.
●Reduced risk of cervical, endometrial, and ovarian cancers [36].
•Cervical cancer – A meta-analysis of 16 studies assessing the incidence of cervical cancer in IUD users reported that women with any history of IUD use were approximately 30 percent less likely to develop cervical cancer (summary odds ratio [OR] 0.64, 95% CI 0.53-0.77) [37]. The proposed mechanism is an altered immune response resulting from device insertion and presence [38,39]. These studies primarily collected data about nonhormonal IUD use.
•Endometrial cancer – A Finnish study of over 90,000 women reported a 50 percent reduction in the risk of endometrial cancer (incidence ratio 0.50, 95% CI 0.35-0.70) and a 40 percent reduction in ovarian cancer (incidence ratio 0.60, 95% CI 0.45-0.76) among women who used at least one LNG IUD for abnormal uterine bleeding [40].
•Ovarian cancer – Another meta-analysis of 11 studies (9 case control, 2 cohort) reported a reduced rate of ovarian cancer with ever-use of an IUD (summary OR 0.68, 95% CI 0.62-0.75) [41]. The mechanisms by which an IUD might reduce cancer risk and the impact of device type on cancer risk are not known.
●Noncontraceptive benefits. (See 'Noncontraceptive benefits' below.)
Because of these factors, patient satisfaction and continuation rates are high [42-44]. Similarly, a 2015 United States study of over 9000 women ages 14 to 45 years using either the LNG or copper 380 mm2 IUDs reported one-, two-, three-, four-, and five-year IUD continuation rates of 88, 79, 70, 63 and 54 percent, respectively [44-46]. A Finnish study including almost 18,000 women using an LNG IUD reported continuation rates at one, two, three, four, and five years of 93, 87, 81, 75, and 65 percent, respectively [42]. For comparison, United States women using short-acting methods (ie, depot medroxyprogesterone acetate or hormonal contraceptive pills, patch, or ring) reported a 30 percent three-year contraceptive continuation rate.
Resumption of fertility after discontinuation is rapid and similar for IUDs [10,12-15], progestin-releasing implants [47,48], and contraceptive pills, rings, and patches [49,50].
Cost effectiveness — All IUDs are highly cost-effective; although the initial cost of the device and insertion can be high, the overall cost decreases with each year of use because no additional expenditure is required. At five years of use, the IUD is one of the most cost-effective methods of reversible contraception available [51]. A 2015 United States cost analysis study that compared the cost of long-acting and short-acting reversible contraceptives calculated that long-acting reversible contraception (including the copper and LNG 52 mg IUD) began saving money after 2.1 years of use when compared with short-acting reversible contraception that included pills, patch, ring, or injection [52].
COPPER IUD
Characteristics — The copper 380 mm2 contains a T-shaped polyethylene frame with 380 mm2 of exposed surface consisting of fine copper wire wound around a vertical stem and copper collars on each of the horizontal arms [10]. A 3 mm ball at the base of the stem decreases the risk of cervical perforation (picture 2) [53]. A white or clear polyethylene monofilament string is knotted through this ball. The frame contains barium sulfate to make it radiopaque. The device is latex free.
●Copper allergy and absorption – Clinically relevant allergy to copper is extremely rare [54]. Serum copper levels are higher in copper 380 mm2 users compared with nonusers and above the normal blood copper level range; however, this increase in circulating copper does not have a negative clinical impact unless the patient has a contraindication or allergy to copper [55]. (See "Intrauterine contraception: Candidates and device selection", section on 'Contraindications'.)
●Emergency contraception – The copper 380 mm2 IUD can be inserted for emergency contraception for at least five days (120 hours) from unprotected intercourse and has the lowest pregnancy rate (<0.1 percent) [56,57]. The device can then be left in place to provide ongoing contraception [58]. (See "Emergency contraception", section on 'What are the emergency contraception methods?'.)
●Risk of sexually transmitted infection – While IUDs do not protect against sexually transmitted infections (STIs), presence of an IUD is not associated with an increased risk of pelvic inflammatory disease (PID) should an STI be acquired [59-61]. Data conflict as to whether or not the risk of STI or PID is greater for users of copper or levonorgestrel IUDs [62,63]. Patients at risk for STI are advised to use it with condoms (internal or external).
•(See "External (formerly male) condoms".)
•(See "Internal (formerly female) condoms".)
Efficacy — With perfect use, the probability of pregnancy in the first year is 0.6 percent; with typical use, the first-year pregnancy rate is 0.5 to 0.8 percent (table 2) [22,64,65]. Women under age 25 experience a slightly higher failure rate, most likely because they are more fertile than older women. These failure rates are comparable to surgical sterilization [66,67].
●Comparison of copper and levonorgestrel IUDs – While failure rates for both IUDs are low overall (figure 1), the rates of failure with the copper IUD may be somewhat higher than with progestin-releasing IUDs, although conflicting data exist [65,68]. In one study of over 61,000 women, the copper IUD first-year failure rate was 0.52 versus 0.06 pregnancies per 100 woman-years for the LNG 52 mg IUD [65]. In addition, the ectopic pregnancy rate was higher for copper IUDs than the LNG 52 mg IUD (0.08 versus 0.02 ectopic pregnancies per 100 woman-years). While the proportion of ectopic pregnancies was higher for women with LNG IUDs compared with copper IUDs (27 versus 15 percent), the overall incidence rate of ectopic pregnancy was higher for copper IUD users because of the somewhat higher overall failure rate. Of note, the copper IUD study group contained more than 30 types of copper IUDs, which may have impacted the results. As an example, IUDs with less than 380 mm2 of copper and inert IUDs are less effective than those containing ≥380 mm2 of copper [69,70].
●Comparison of copper IUD and tubal ligation – In a study comparing interval laparoscopic tubal ligation with either copper 380 mm2 or levonorgestrel IUDs (all types), unintended pregnancy rates were similar between tubal ligation and the copper 380 mm2 IUD (adjusted incident rate ratio [aIRR] 0.92, 95% CI 0.82-1.05) but lower with the levonorgestrel IUDs (aIRR 0.72, 95% CI 0.64-0.82). Postpartum tubal ligation was not included in this retrospective cohort study of Medicaid insurance claim data from California. Additional discussion of permanent contraception and IUDs is available separately. (See "Overview of female permanent contraception", section on 'Counseling and informed consent'.)
Duration of use — The copper 380 mm2 is approved by the US Food and Drug Administration to remain in place for 10 years; this may vary elsewhere. However, some clinicians use the copper 380 mm2 for more than 10 years before exchanging it for a new IUD. The use of the copper 380 mm2 beyond 10 years is supported by several studies [71-73]. In two studies of 314 women who used the copper 380 mm2 for an additional two years (10 to 12 years from insertion), no pregnancies were reported [71,72]. Additionally, no pregnancies were reported in the subgroup of eight women who used the device for up to 16 years [72].
We counsel patients about the advantages of extended use of the copper 380 mm2 (cost savings, prolongation of contraception, and avoidance of an additional intrauterine procedure). However, for patients with strong preferences for following the package insert recommendation to remove the copper 380 mm2 at 10 years, we remove and replace as desired or indicated.
In addition to patient preference, extended use depends on patient age at insertion because age impacts fertility.
●For patients younger than 25 years at the time of copper 380 mm2 IUD placement, we recommend replacing the IUD after 10 years of use because younger women are more fertile.
●For patients age 25 to 34 years at the time of copper 380 mm2 IUD placement, the IUD may be left in place for up to 12 years [71,72].
●For patients age 35 years or older at the time of copper 380 mm2 IUD placement, we recommend leaving the IUD in place until menopause if the patient is happy with the method and still requires contraception [74].
Noncontraceptive benefits — Noncontraceptive benefits of the copper IUD include continued menstrual cyclicity, reduced risk of cervical cancer, and possibly a reduction in endometrial cancer [36,37,75-78].
LEVONORGESTREL IUD
Devices and characteristics — The levonorgestrel (LNG)-releasing IUDs are available in three different formulations in the United States:
●LNG 52 mg IUD – This IUD has an initial LNG release rate of approximately 20 mcg/day, which declines to an average release of 10 mcg/day at five years [15]. These devices are approved by the US Food and Drug Administration (FDA) for eight years (abbreviated LNG 52 mg, commercial names Mirena and Liletta) [12,15,79-81].
●LNG 19.5 mg IUD – The initial LNG release rate is 17.5 mcg/day, which declines to 7.4 mcg/day at five years and is FDA approved for five years of use (abbreviated LNG 19.5, commercial name Kyleena) [13].
●LNG 13.5 mg IUD – The initial LNG release rate is approximately 14 mcg/day, which declines to 5 mcg/day at three years and is FDA approved for three years of use (abbreviated LNG 13.5, commercial name Skyla) [14].
Both 52 mg IUDs (picture 3) consist of a T-shaped polyethylene frame measuring 32 by 32 mm, with a collar containing 52 mg of LNG dispersed in polydimethylsiloxane attached to a vertical stem [15]. A string is attached to the distal end of the stem. The insertion tube diameter for the 52 mg LNG IUDs ranges from 4.4 to 4.8 mm [12,15]. Both devices contain barium in the frame to make them detectable by radiograph.
Like the 52 mg IUDs, the LNG 19.5 and the LNG 13.5 also use the T-shaped design. In contrast, the LNG 19.5 and LNG 13.5 have a smaller frame (28 by 30 mm versus 32 by 32 mm) and are smaller in diameter (3.8 mm inserter versus 4.4 mm) [12-15]. The smaller diameter may allow easier insertion for women with very small uterine cavities or cervical stenosis, but there are no comparative trials. The LNG 19.5 and LNG 13.5 contain a silver ring at the top of the stem to distinguish them on ultrasound and barium in the frame to make them detectable by radiograph [13,14].
The progestin effect of hormone-releasing IUDs is primarily at the level of the endometrium [82]. As an example, the endometrial concentration of LNG is 1000 times higher with the LNG-releasing IUDs compared with the LNG subdermal implant [83]. However, the high endometrial concentration from the IUDs does not result in a high plasma concentration; the absolute plasma LNG levels are much lower. For the 13.5 mg, 19.5 mg, and 52 mg LNG IUDs, the plasma LNG concentration is highest seven days postinsertion with levels between 100 and 250 pg/mL. There is a gradual decline over time with wide individual variation [12-15,84-86]. This level is half that seen with progestin implants (350 pg/mL) and much less than that associated with progestin-only pills (1500 to 2000 pg/mL) [87,88] but high enough to cause systemic side effects in some users. Serum estradiol levels are not affected [85].
In contrast to the copper 380 mm2, there are limited published data on the use of the LNG 52 mg IUD for emergency contraception (EC) but its use for EC is supported. A trial that randomly assigned 711 individuals requesting EC to either LNG 52 mg or copper 380 mm2 IUDs reported similar pregnancy rates for the two devices (LNG 52 mg: 1 pregnancy of 317 and copper 380 mm2 IUD: 0 pregnancies of 321; between group absolute difference of 0.3 percent, 95% CI 0.01-1.7) [89]. (See "Emergency contraception", section on 'What are the emergency contraception methods?'.)
Efficacy — All levonorgestrel IUDs have low (1 percent or less) rates of unintended pregnancy (ie, failure).
●Comparison of levonorgestrel IUDs – With perfect use of the LNG 52 mg, the probability of pregnancy in the first year is 0.1 percent; with typical use, the first-year pregnancy rate is 0.1 to 0.2 percent (table 2) [65,90,91]. With five years of continuous LNG 52 mg use, the cumulative pregnancy rate is 0.7 percent [12,92,93]. The clinical trial for the LNG 52 mg reported cumulative pregnancy rates of 0.14 percent at one year and 0.87 percent at four years [94]. In a phase three trial of the LNG 19.5 and LNG 13.5 devices, the cumulative pregnancy rates were 0.2 and 0.4 percent at one year and 0.9 and 1.0 percent at three years, respectively [95]. These rates are comparable to those of sterilization procedures (figure 1) [66]. (See "Overview of female permanent contraception", section on 'Counseling and informed consent'.)
●Comparison of copper and levonorgestrel IUDs – While failure rates for copper and levonorgestrel IUDs are low overall (figure 1), the rates of failure with the copper IUD may be somewhat higher than with progestin-releasing IUDs, although conflicting data exist [65,68]. (See 'Efficacy' above.)
●Risk of ectopic pregnancy – While the overall risk of pregnancy is low with LNG IUDs, if a pregnancy is conceived, ectopic pregnancy is more common in women using LNG IUDs compared with copper IUDs. In a study of over 61,000 European women with a newly inserted IUD, the proportion of ectopic pregnancies was higher in LNG users compared with copper IUD users (27 versus 15 percent) [65]. However, as discussed above, the overall incidence risk of ectopic pregnancy was lower with LNG IUDs because of the lower absolute risk of pregnancy. A retrospective cohort study of over 2000 Swedish women diagnosed with an ectopic pregnancy found the overall risk of an ectopic pregnancy was low among LNG IUD users. However, the risk was higher among users of the 13.5mg (Pearl Index [PI] 0.136, 95% CI 0.106-0.176) and 19.5 mg (PI 0.037, 95% CI 0.021-0.067) LNG IUD compared with the 52 mg LNG IUD (PI 0.009, 95%CI 0.006-0.014) [96]. Thus, women who conceive while using any IUD should be evaluated for ectopic pregnancy. (See 'Efficacy' above.)
●Comparison with permanent contraception – In a study comparing interval laparoscopic tubal ligation with either copper 380 mm2 or levonorgestrel IUDs (all types), unintended pregnancy rates were lower with the levonorgestrel IUDs (adjusted incident rate ratio [aIRR] 0.72, 95% CI 0.64-0.82) but similar between tubal ligation and the copper 380 mm2 IUD (aIRR 0.92, 95% CI 0.82-1.05) [67].
•(See 'Efficacy' above.)
•(See "Overview of female permanent contraception", section on 'Counseling and informed consent'.)
Duration — Both LNG 52 mg IUDs are approved for up to eight years [12,15,73,80,81,97-99].
Supporting data include:
●Five years of use – After five years of use, the LNG 52 mg releases approximately double the amount of LNG as the LNG 13.5 mg IUD releases after three years [100].
●Six and seven years of use – In a prospective cohort study of nearly 500 women with extended use of LNG 52 mg IUDs, two pregnancies were reported during the two-year extended observation, for six- and seven-year cumulative failure rates of 0.25 and 0.43 per 100 woman-years [97]. A different chart review of 766 women who used an LNG 52 mg beyond five years reported no pregnancies after a mean of 73 months of use (range 61 to 184 months) [98].
●Beyond eight years of use – In an extension of a trial that initially enrolled participants up to eight years of LNG 52 mg IUD use, no pregnancies were reported by the participants who continued the IUD for 9 (n = 83) or 10 years (n = 77) of total use [101]. In both groups, the majority of patients were younger than 40 years at study completion (64 patients at 9 years [77 percent] and 44 patients at 10 years [57 percent]).
The LNG 19.5 and 13.5 have a lower LNG dose, and there is no evidence supporting extended use of these IUDs past the FDA-approved duration [74].
Noncontraceptive benefits — Noncontraceptive benefits of 52 mg LNG IUDs include reduction in heavy menstrual bleeding, anemia, dysmenorrhea, endometriosis-related pain, endometrial hyperplasia, pelvic inflammatory disease, and cervical cancer [36,37,102-110]. The use of the LNG 52 mg IUD for treatment of heavy menstrual bleeding is FDA approved [12,15]. LNG use of 52 mg LNG IUDs for these other noncontraceptive indications is off-label but a common practice that is supported by strong medical evidence. For obese individuals with complex atypical hyperplasia, several observational studies have reported improved resolution with LNG IUD treatment compared with systemic progestin therapy [111,112]. There is also a reduction in the risk of endometrial cancer and ovarian cancer with LNG IUDs. However, risk of high-grade cervical intraepithelial neoplasia may be somewhat increased with LNG IUD use [77,78].
The use of the IUD or surgical procedures to treat heavy menstrual bleeding is reviewed in detail elsewhere.
There is minimal information on the noncontraceptive benefits of the LNG 19.5 and 13.5 IUDs.
IMPACT OF DEVICE TYPE ON BLEEDING PATTERN — Both types of IUDs are associated with alterations in bleeding patterns, although the changes differ. In general, copper IUDs are associated with heavier menstrual bleeding while levonorgestrel (LNG) IUDs can cause lighter bleeding, amenorrhea, or minimal change, depending on the LNG dose.
Copper IUD — Women considering the copper IUD are counseled that menses may be heavier, longer, or more painful, particularly in the first several cycles after insertion. In a study of over 3800 women using either the copper 380 mm2 or the LNG 52 mg, at three months the copper IUD users had more cramping (63 versus 32 percent), increased bleeding volume (71 versus 12 percent), and increased bleeding frequency (41 versus 33 percent) than LNG 52 mg users [113]. These symptoms improved rapidly, and at six months the copper IUD users reported symptom reduction to levels similar to the LNG 52 mg users (cramping 14 versus 12 percent, increased bleeding volume 19 versus 8 percent, increased bleeding frequency 13 versus 11 percent). The amount of baseline menstrual bleeding a woman has prior to copper IUD insertion does not appear to impact the 12-month device continuation rate; women with baseline heavy menstrual bleeding are not more likely than those without to remove the device [114]. Nonsteroidal anti-inflammatory drugs (NSAIDs) appear to decrease menstrual blood loss and bleeding duration, particularly in women with heavy or prolonged bleeding [115]. (See "Intrauterine contraception: Management of side effects and complications", section on 'Post-insertion bleeding' and "Intrauterine contraception: Management of side effects and complications", section on 'Irregular bleeding and/or cramping'.)
While the average monthly menstrual blood loss may increase by up to 55 percent throughout the duration of copper IUD use, it rarely leads to anemia for most women. A systematic review reported the hemoglobin concentration decreased by 0.36 to 0.94 g/dL over 12 months in copper IUD users who were not anemic at baseline [116].
Levonorgestrel-releasing IUDs — For the LNG-releasing IUDs, the most common changes in bleeding patterns include prolonged bleeding (59 percent), unscheduled bleeding (up to 52 percent), amenorrhea (6 to 20 percent), and spotting (23 to 31 percent) at the end of one year of use [12-14,94,117]. Women should be reassured that the changes in bleeding patterns are a side effect of the hormone on the uterine lining and are not dangerous. All women should be counseled that intermenstrual bleeding is common, especially with the onset of use, and improves by six months of use [12,14,94,113]. A study including 3001 LNG 52 mg users who were surveyed at three and six months of IUD use reported that, by six months, 62 percent of reported lighter bleeding and 55 percent reported decreased frequency of bleeding [113]. The management of these and other hormonal side effects, such as breast tenderness, mood changes, and acne, is discussed in detail separately. (See "Intrauterine contraception: Management of side effects and complications".)
While changes in bleeding patterns are common with the 52 mg, 19.5 mg, and 13.5 mg LNG IUDs, the amenorrhea rate differs substantially among the devices. After one year of use, amenorrhea is reported by approximately 20 percent of LNG 52 mg IUD users, 12 percent of LNG 19.5 mg users, and 6 percent of LNG 13.5 mg users [12-14,94,117,118]. At the end of three years of use, 30 to 50 percent of LNG 52 mg IUD users reported amenorrhea compared with 20 and 12 percent of women using the LNG 19.5 mg and LNG 13.5 mg, respectively [12-14,94]. Therefore, women who prefer to avoid menstrual bleeding may benefit from a 52 mg device, and those who prefer the reassurance of monthly menstruation may benefit from the 19.5 mg or 13.5 mg devices. Both groups must be counseled that the desired menstrual change may not occur; some women with the 52 mg devices will continue to have monthly periods, and some with the lower dose devices will become amenorrheic.
Bleeding-related discontinuation rates — With supportive counseling, most women are able to tolerate the changes in bleeding patterns, and discontinuation rates are low overall for all devices. In a study of over 3800 women using either the copper 380 mm2 or the LNG 52 mg, the overall satisfaction rate for the copper IUD was greater than 90 percent, and the device discontinuation rate was approximately 6 percent at six months of use [113]. In the six-year LNG 52 mg clinical trial, 2.3 percent of women discontinued the device early because of bleeding complaints compared with a 12 percent overall early discontinuation rate [94]. Similarly, in the three-year LNG 13.5 clinical trial, the early discontinuation rates were 4.6 percent for bleeding complaints and 18 percent overall [14]. For comparison, other reasons for discontinuation of the LNG 13.5 IUD included device expulsion (3.2 percent), acne/seborrhea (2.9 percent), abdominal pain (2.5 percent), dysmenorrhea/uterine spasms (2.0 percent), and pelvic pain (1.8 percent). (See "Intrauterine contraception: Management of side effects and complications", section on 'Irregular bleeding and/or cramping' and "Intrauterine contraception: Management of side effects and complications", section on 'Continued bleeding and cramping'.)
RISK OF EXPULSION — The incidence of expulsion is 3 to 10 percent for the TCu380 and 3 to 6 percent for the levonorgestrel IUD in the first year of use [22,64,71,119,120]. The symptoms and risk factors of expulsion are discussed separately. (See "Intrauterine contraception: Management of side effects and complications", section on 'Expulsion' and "Contraception: Postabortion", section on 'Intrauterine device' and "Contraception: Postpartum counseling and methods", section on 'Intrauterine devices'.)
OTHER IUD TYPES
Inert IUDs — Unmedicated IUDs are approved for use outside the United States and are popular because they can remain in place for 20 years or more. The devices are composed of inert materials such as plastic or stainless steel. Flexible stainless steel rings visible on radiographs, but with no string, were widely used in China [121]. The pregnancy rates for the Lippes Loop vary by device size and range from 1 to 4.8 per 100 women-years [122,123]. The higher failure rate of the stainless steel ring compared with copper T IUDs (10.6 versus 1.7 percent) led the Chinese State Family Planning Commission to stop production of the ring in 1993 and to encourage the use of copper or levonorgestrel (LNG)-releasing IUDs instead [22,121,124].
As medicated IUDs are more effective, we recommend replacing inert IUDs with LNG-releasing or copper IUDs, especially for women below age 40, as they have higher fertility rates. We also inform women ages 40 and older that LNG and copper IUDs are more effective than inert IUDs but do not encourage switching if the patient is happy with her device.
Frameless IUDs — Frameless IUDs, which are available outside of the United States, contain either copper or LNG that has been attached to a nonresorbable filament. The GyneFix 330 is made up of copper cylinders threaded onto a polypropylene suture instead of the plastic frame common to other IUDs [125,126]. The FibroPlant is a frameless LNG-releasing IUD consisting of a nonresorbable thread attached to a fibrous delivery system that releases 14 or 20 mcg of LNG per day [127]. These devices are anchored to the endometrium using an insertion technique that requires additional training as the technique is different from the other types of IUDs. The intrauterine ball SCu300A is comprised of copper beads strung on a memory alloy wire that curls into a ball shape on insertion into the uterus [128].
Advantages of these systems include small size, high efficacy, and high tolerability. They may be as effective as conventional IUDs and more adaptable to variations in the shape of the uterine cavity [129,130]. However, the risk of expulsion may vary depending on the IUD shape [131].
SOCIETY GUIDELINE LINKS — Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: Contraception".)
INFORMATION FOR PATIENTS — UpToDate offers two types of patient education materials, "The Basics" and "Beyond the Basics." The Basics patient education pieces are written in plain language, at the 5th to 6th grade reading level, and they answer the four or five key questions a patient might have about a given condition. These articles are best for patients who want a general overview and who prefer short, easy-to-read materials. Beyond the Basics patient education pieces are longer, more sophisticated, and more detailed. These articles are written at the 10th to 12th grade reading level and are best for patients who want in-depth information and are comfortable with some medical jargon.
Here are the patient education articles that are relevant to this topic. We encourage you to print or e-mail these topics to your patients. (You can also locate patient education articles on a variety of subjects by searching on "patient info" and the keyword(s) of interest.)
●Basics topics (see "Patient education: Intrauterine devices (IUDs) (The Basics)" and "Patient education: Long-acting methods of birth control (The Basics)" and "Patient education: IUD insertion (The Basics)" and "Patient education: IUD removal (The Basics)")
●Beyond the Basics topic (see "Patient education: Long-acting methods of birth control (Beyond the Basics)")
SUMMARY AND RECOMMENDATIONS
●Device types – The intrauterine device (IUD) is the most commonly used method of reversible contraception worldwide and is used by an average of 23 percent of female contraceptive users globally. Two types of IUDs are available in the United States, copper-containing and levonorgestrel-releasing (LNG) devices. The LNG-releasing devices are available in multiple formulations. (See 'Prevalence of use' above and 'Types of IUDs' above.)
●Mechanism of action – Multiple mechanisms appear to contribute to the contraceptive action of IUDs (table 1). Pregnancy appears to be prevented by a foreign body effect induced by the IUD frame and by local changes caused by the released medication. (See 'Mechanism of action' above.)
●Benefits of use – There are multiple benefits to IUD use, including that IUDs are one of the most effective methods of contraception (figure 1), which result in high user satisfaction rates. The IUD is also cost-effective when used over multiple years. (See 'Benefits' above and 'Cost effectiveness' above.)
●Copper IUD (copper 380 mm2 ) – The copper 380 mm2 has a T-shaped polyethylene frame with 380 mm2 of exposed surface consisting of fine copper wire wound around a vertical stem and copper collars on each of the horizontal arms; a 3 mm ball at the base of the stem decreases the risk of cervical perforation (picture 2). The copper 380 mm2 can also be used for emergency contraception and left in place for continued contraception. (See 'Characteristics' above.)
•Efficacy – With perfect use, the probability of pregnancy in the first year is 0.6 percent; with typical use, the first year pregnancy rate is 0.5 to 0.8 percent (table 2). While failure rates for both copper and LNG-releasing IUDs are low overall, the rates of failure with the copper IUD are somewhat higher than with progestin-releasing IUDs. (See 'Efficacy' above.)
•Duration of use – The copper 380 mm2 is approved by the US Food and Drug Administration (FDA) to remain in place for 10 years. However, this may vary elsewhere since the use of the copper 380 mm2 beyond 10 years is supported by several studies. (See 'Duration of use' above.)
•Impact on menses – Women considering the copper IUD are counseled that menses may be heavier, longer, or more painful, particularly in the first several cycles after insertion. These changes in menstrual symptoms generally do not cause women to remove the IUD and rarely lead to anemia. (See 'Copper IUD' above.)
●Levonorgestrel IUDs – There are four types of LNG-releasing IUDs available in the United States, with progestin-release rates ranging from 14 to 20 mcg/day (picture 3). The progestin effect of hormone-releasing IUDs is primarily at the level of the endometrium. (See 'Devices and characteristics' above.)
•Efficacy – With perfect use of the LNG 52 mg IUDs, the probability of pregnancy in the first year is 0.1 percent; with typical use, the first-year pregnancy rate is 0.1 to 0.2 percent (table 2). (See 'Efficacy' above.)
-Duration of use – The duration of use varies with the type of LNG IUD. The LNG 52 mg devices are approved for up to eight years of use by the FDA (commercial names Mirena and Liletta). The LNG 19.5 mg and 13.5 mg have lower LNG doses and are approved for five and three years respectively. There is no evidence supporting extended use of the LNG 19.5 mg and 13.5 mg IUDs. (See 'Duration' above.)
•Impact on menses and related benefits – Noncontraceptive benefits of 52 mg LNG IUDs include reduction in heavy menstrual bleeding, anemia, dysmenorrhea, endometriosis-related pain, endometrial hyperplasia, pelvic inflammatory disease, and cervical cancer. (See 'Noncontraceptive benefits' above.)
●Other IUD types – Multiple types of IUDs are available globally. Popular devices include inert and frameless IUDs (available outside the United States).
•Inert or unmedicated IUD – Inert, or unmedicated, IUDs are popular because they can remain in place for 20 years or more. The devices are composed of inert materials such as plastic or stainless steel. (See 'Inert IUDs' above.)
•Frameless IUD – Frameless IUDs, which are available outside of the United States, contain either copper or LNG that has been attached to a nonresorbable filament. Advantages of these systems include small size, high efficacy, and high tolerability. They may be as effective as conventional IUDs and more adaptable to variations in the shape of the uterine cavity. (See 'Frameless IUDs' above.)
ACKNOWLEDGMENTS — The UpToDate editorial staff acknowledges Gillian Dean, MD, MPH, and Alisa Goldberg, MD, MPH, who contributed to an earlier version of this topic review.
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