Contraceptive Technology Reports-The Levonorgestrel Intrauterine System: An Effective New Contraceptive Option
Author: Andrew M. Kaunitz, MD, Professor and Assistant Chair, Department of Obstetrics and Gynecology, University of Florida Health Science Center/Jacksonville.
Peer Reviewer: Amy Pollack, MD, MPH, President, EngenderHealth, New York City.
Introduction
Despite data showing that intrauterine devices (IUDs) are safe, convenient, and highly effective for appropriately selected candidates, these devices remain an underutilized contraceptive option in the United States. Indeed, many women will choose sterilization rather than IUDs because of concerns about the method’s mechanism of action, as well as their safety and comfort.
The newest type of IUD is an intrauterine hormonal contraceptive system called the levonorgestrel intrauterine system (LNG IUS), also known as Mirena, from Berlex Laboratories of Montville, NJ. It was approved by the Food and Drug Administration in December 2000, and might help to change the perception of IUDs in the United States thanks to its high efficacy rate, lack of serious side effects, and important therapeutic benefits. The unit cost is approximately $355.
Structure and History
The LNG IUS is comprised of a small T-shaped frame that holds a cylinder containing levonorgestrel, the same potent progestin found in many combination oral contraceptives (OCs), progestin-only "mini-pills," and the contraceptive implant, Norplant. The system is 32 mm in length and, when placed in the uterus, releases levonorgestrel into the uterine cavity at a rate of 20 mcg a day. It is approved for five years of use and its effectiveness has been demonstrated for seven years.
LNG IUS has been available for use in Europe for more than a decade and has been used by more than 2 million women worldwide.
Mechanism of Action
The LNG IUS prevents pregnancy in much the same way that levonorgestrel-containing implants and mini-pills do: The progestin thickens cervical mucus, which inhibits sperm motility and function.1-3 Typically, use of the LNG IUS does not suppress ovulation; indeed, 85% of menstrual cycles are ovulatory, and background serum estrogen levels among users are comparable to those of ovulatory women not using hormonal contraception.4
The levonorgestrel in the LNG IUS also prevents endometrial proliferation - endometrial suppression takes full effect three months after insertion of the system - leading to a substantial reduction in menstrual flow and, often, amenorrhea.5,6 A weak foreign-body (sterile inflammatory) effect also has been noted, but is less pronounced than with copper-releasing IUDs.5 The system is not an abortifacient and does not appear to have a role as an emergency contraceptive.3
Pharmacokinetics
After insertion of the LNG IUS, levonorgestrel is released into the uterine cavity. It is then rapidly absorbed from the basal layer of the endometrium into the systemic circulation. Within 15 minutes after insertion, levonorgestrel can be detected in the serum.7 Maximum plasma levels occur within a few hours of insertion, and hormone levels reach steady-state (around 150 pg/mL to 200 pg/mL) within several weeks.8 Levonorgestrel plasma levels are lower than those observed in women using Norplant, mini-pills, and combination OCs, and without the peaks and valleys common to the latter methods.9-12 Plasma levels of levonorgestrel decline over five years’ time from a high of approximately 250 pg/mL just after insertion to a low of 100 pg/mL.13-14
The release of levonorgestrel into the uterine cavity results in high concentrations of progestin in the endometrium ranging from 470 ng/g to 1,500 ng/g tissue wet weight. This occurs within weeks of insertion of the system. Tissue concentrations subsequently fall over time.11
Efficacy
The overall failure rate during use of the LNG IUS is 0.14 per 100 woman-years, based on more than 12,000 woman-years of use.15
This rate is comparable to annual failure rates for female sterilization.16 Over five years, the cumulative pregnancy rate is 0.71.15
Safety and Side Effects
For several months after insertion, LNG IUS users may experience edema, headache, breast tenderness, acne, lower abdominal or back pain, vaginal discharge, or nausea.16,17 These side effects tend to abate with time. Spotting may occur during the initial use (e.g., the first six months), and absence of bleeding (amenorrhea) has been observed in 20% of users at one year.17,18 The development of functional ovarian cysts also has been observed, as occurs with other progestin-only contraceptive pills and implants, but such cysts rarely require treatment or necessitate removal of the intrauterine system. Typically, they resolve on their own.19 Clinical trials have not suggested that the LNG IUS causes weight gain.
Serious side effects, as with other intrauterine contraceptives, occur rarely with LNG IUS and include:
• Pelvic Inflammatory Disease (PID). The rate of PID associated with LNG IUS use is less than one per 100 woman-years at five years.20 It has been postulated that the levonorgestrel in LNG IUS might have a protective effect on the cervical mucus, making the ascent of pathogens to the upper genital tract less likely to occur. This protection also might be a result of endometrial suppression or reduced bleeding associated with LNG IUS use.21
For all intrauterine contraceptive devices, the risk of PID diminishes substantially with time and is greatest at insertion.22 Only one woman in 1,000 will develop PID in the first three months of using an IUD, and a recent meta-analysis showed that there is no overall benefit to administering prophylactic antibiotics.23,24
• Sepsis. Four cases of Group A streptoccocal sepsis have been reported among 1.3 million estimated users of the LNG IUS since 1989. In all cases, the patients experienced severe pain within hours of insertion of the system and developed sepsis within days. All were treated successfully.25
• Perforation. The risk of uterine perforation with the LNG IUS is very low: less than one per 1,000 insertions.25
• Expulsion. The five-year cumulative expulsion rate for the LNG IUS is 4.9 per 100 woman-years. Expulsion is most likely to occur during the first six months after insertion.16
Return to Fertility
After removal of the LNG IUS, fertility quickly returns to baseline.26-29 At 12 months after removal, the cumulative conception rate ranges between 79% and 96%.27,28 In addition, no abnormalities have been detected or reported among children born of women who have used the LNG IUS for contraception.17
Comparison to Other IUDs
In contrast with copper-releasing IUDs, which increase menstrual blood loss, use of the LNG IUS reduces blood loss. In contrast with the Progesterone T, the LNG IUS lowers the risk of ectopic pregnancy. The annual failure rate for the LNG IUS is comparable to that for the Copper T 380A and lower than that of the progesterone T. The LNG IUS is approved for five years of use, compared with the Copper T IUD, which is approved for 10 years, and the progesterone IUD, which is approved for one year of use. The latter device releases 66 mcg of progesterone into the uterine cavity each day, whereas LNG IUS releases 20 mcg of levonorgestrel a day.
 |
Pregnancy rates. The system is extremely efficacious. The cumulative five-year failure rates have ranged from 0.5% to 1.1%, in comparison to the Copper T 380A IUD, which has a 1.4% five-year cumulative failure rate, and sterilization, which overall has an 1.3% five-year failure rate.15,16
PID. Two randomized trials compared the LNG IUS to copper IUDs. In one multicenter, prospective, randomized trial of the LNG IUS vs. a copper IUD, the cumulative removal rate at 36 months for PID was 0.5 per 100 women for LNG IUS and two per 100 women for the copper IUD. At 60 months, these rates climbed to 0.8 for the LNG IUS and 2.2 per 100 for the study Copper T IUD.15 A second prospective trial found LNG IUS had a comparable removal rate for PID (approximately four per 100 women) at seven years to the Copper T 380A IUD.30
Ectopic Pregnancy. Use of the LNG IUS confers less risk of ectopic pregnancy than other IUDs or use of no contraceptive method at all. Women using LNG IUS have a 0.20 incidence of ectopic pregnancy per 1,000 woman-years of use vs. 0.34 for the copper IUD, 3.60 for the progesterone IUD, and 1.20-1.60 for no method.31
Menstrual Patterns. Use of the LNG IUS decreases blood loss and duration of blood loss.32 In comparison to users of the Copper T380A IUD, who experience four to five days of withdrawal bleeding during the first two years of use, use of the LNG IUS is associated with one day of bleeding from eight months of use on.32,33 After 12 months of use, 20% of women of those using the LNG IUS are amenorrheic.18
Use of the LNG IUS also often results in a substantial decrease in dysmenorrhea: For instance, Nilsson et al. reported that 35% of LNG IUS users experienced improvements in dysmenorrhea compared with 9% of copper IUD users.33
Therapeutic Benefits
The LNG IUS also differs from the other two IUDs available in the United States in that its use appears to confer several important noncontraceptive therapeutic benefits.
Menorrhagia. Studies suggest that the LNG IUS effectively treats menorrhagia. In one trial of 25 women with menorrhagia and adenomyosis, insertion of LNG IUS reduced menstrual blood loss over 12 months by 90% to 97% compared with pre-treatment levels. These changes were accompanied by a significant increase in hemoglobin levels and a decrease in uterine volume.34
In an open, randomized Finnish trial of 56 women aged 33-49 years conducted to assess whether the levonorgestrel intrauterine system could provide an alternative to hysterectomy for excessive uterine bleeding, it was found that at six months, 64% of women in the LNG IUS group had canceled their surgery for hysterectomy compared with 14.3% of women who continued with standard medical therapy. At an average follow-up of three years, half of the women were still using the LNG IUS, which suggests the system may offer a long-term conservative alternative to hysterectomy for women suffering from menorhagia.35
Another study found that the mean reduction in blood loss with the LNG IUS (90%) was greater than that reported for nonsteroidal anti-inflammatory drugs (NSAIDs) (25% to 35%), danazol (60%), tranexamic acid (50%), oral progestogens (12%), and oral contraceptives (50%).36
Prevention of endometrial hyperplasia during estrogen replacement therapy (ERT). Withdrawal bleeding is the most common reason that women discontinue hormone replacement therapy. The levonorgestrel intrauterine system suppresses the endometrium to such an extent that 83% to 88% of users cease to have withdrawal bleeding at 12 months, leading to an 82% continuation rate at three years.34,37,38 The LNG IUS also might be an appropriate choice for noncontraceptive use in perimenopausal women who are experiencing endometrial proliferation and uterine bleeding as a consequence of oral or transdermal estradiol use.27,39,40
Suitable Candidates
The LNG IUS represents an appropriate contraceptive option for women in mutually monogamous sexual relationships who have had at least one child. Insertion should be performed within seven days of the onset of a normal menstrual period, first-trimester abortion, or six weeks after delivery.25
Contraindications
Women who should not use LNG IUS include those:
• with known or suspected pregnancy;
• genital infection;
• confirmed or suspected uterine or cervical malignancy;
• undiagnosed abnormal uterine bleeding;
• congenital or acquired uterine anomalies that might interfere with proper insertion of the system, including fibroids if they distort the uterine cavity;
• acute liver disease or liver tumor;
• active thrombophlebitis or thromboembolic disorders.25
Insertion Technique
The insertion technique for the LNG IUS is distinct from techniques used for other IUDs. Insertion is performed with a one-hand technique rather than two hands. The system is opened inside the endometrial cavity but before reaching the fundus, and the system’s strings are longer than those of the Copper T IUD. As with all IUDs, the skill of the provider in inserting the system can impact expulsion and complication rates. With all IUDs, close attention to sterile technique is important when inserting the LNG IUS. The packaging for the LNG IUS, which allows no-touch calibration of the flange and loading of the device into the insertion tube, facilitates strict asepsis. Hence, supervised training in the insertion technique for the LNG IUS is essential.
Prior to inserting the device, the clinician should:
• review the method with the patient and obtain written consent;
• examine the patient to exclude the presence of vaginitis/ cervicitis and establish the size and position of her uterus. If the clinician deems this appropriate, testing for chlamydial and gonococcal infection should be performed. (For information on the insertion technique, see table, at left.)
| Table 1. Insertion Technique |
| • Use aseptic technique during insertion. |
| • Cleanse the cervix and vagina with antiseptic solution. |
| • With a tenaculum, grasp the upper lip of the cervix. Apply light traction to align the cervical canal with the uterine cavity. |
| • Sound the uterus with a calibrated plastic (e.g. endometrial biopsy device) or metal sound. Depths fewer than 6 cm or more than 9 cm contraindicate insertion of the LNG IUS. Occasionally, use of cervical dilators might be necessary prior to LNG IUS insertion. Some clinicians premedicate patients with nonsteroidal anti-inflammatory agents. |
| • Open the sterile package containing the intrauterine system. |
| • Release the threads of the system so they hang freely, and make sure the slider is in the furthest position away from you (closest to the patient). |
| • Check to make sure the arms of the system are horizontal. If they aren’t, align them on a flat, sterile surface while maintaining moderate pressure. |
| • Pull on both threads to draw the system into the insertion tube. The knobs at the ends of the arms now will close the open end of the inserter. Fix the threads tightly in the cleft at the near end of the handle. |
| • Set the flange to the depth measured during sounding. The system’s package provides a convenient surface with a groove to facilitate flange adjustment. |
| • Insert the LNG IUS while maintaining firm pressure on the slider with your forefinger or thumb, ensuring that the slider remains in position (furthest from you/closest to the patient). |
| • Move the inserter through the cervical canal into the uterus until the flange is 1.5- 2 cm from the cervix. Do not force the inserter. |
| • Hold the inserter steady and release the arms by pulling the slider back until it reaches the raised horizontal mark on the handle. |
| • Hold the slider in position, and gently push the inserter inward until the flange touches the cervix. The system should be in the fundal position. (You can tell this has occurred when you meet resistance while pushing the insertion tube against the fundus.) Don’t be concerned if the flange is pushed a short distance along the tube by the cervix; because the arms of the system are unfolded and you’re not exerting excess force, this should not result in perforation. |
| • While maintaining the inserter steady in position against the top of the uterine fundus, release the intrauterine system by pulling the slider all the way back (toward you/away from the patient). The threads automatically will release from the cleft. |
| • After ensuring that the threads are not tangled, remove the inserter from the uterus. Make sure the threads run freely through the tube, and don’t pull the system away from its fundal position. |
| • Cut the threads to leave approximately 2 cm of thread visible outside the cervix. |
| Source: Mirena labeling. On file: Berlex Laboratories, Montville, NJ. 2000. |
If You Question Proper Insertion
If there is concern that LNG IUS is not properly positioned in the uterus, check the placement with vaginal ultrasound. Remove the LNG IUS if it is not fundally positioned. Do not reinsert a used system.
Potential Insertion Problems
Difficulty might be experienced when attempting to enter the uterine cavity with the LNG IUS. This situation often may be overcome by opening the speculum further and placing more traction on the tenaculum, straightening the cervix, and bringing it closer to you. Be sure to recheck the direction of the endometrial cavity with uterine sounding after these maneuvers, and, if appropriate, use local anesthesia and cervical dilators.
The system also might get stuck within the plunger. This indicates that the LNG IUS was loaded in the wrong horizontal position and/or that too much pressure was used to pull the threads. In this scenario, discard the system and start over with a new system.
To ensure success with insertion:
• Maintain firm contact with the slider during the entire insertion process.
• Envision the space needed for the system’s arms to swing open inside the uterus.
• Clinicians wanting to insert this IUS are being encouraged to attend one of the 200 training programs being held throughout the country. For more information on training sessions in your community, or to request one, call toll-free (866) LNG-IUS1.
Patient Counseling Following Insertion
After insertion, schedule patients for a follow-up appointment within three months to check for partial or complete expulsion of the system. Caution them that the intrauterine system does not protect against sexually transmitted diseases (STDs). Instruct women who develop STD risk factors during use of the LNG IUS, as with any IUD, to use condoms in addition to the IUS. After the initial follow-up visit, patients should return for routine well-woman care as would be appropriate for women not using IUDs.
All patients should be educated:
• to expect irregular periods for three to six months after insertion. Most women will experience spotting or light bleeding, but a few may have heavier-than-normal bleeding. These menstrual irregularities typically abate within a few months of insertion;
• not to be alarmed if they develop amenorrhea. An absence of bleeding occurs in 1/5 of women who use the LNG IUS for a year or longer. Typically, amenorrhea is not a sign of pregnancy, ovarian or pituitary dysfunction, or the onset of menopause. What’s more, menstruation will return after removal of the system. Performance of urine pregnancy tests at home or at the office might provide reassurance to LNG IUS users concerned about the possibility of pregnancy;
• to check for the LGN IUS’ threads at the top of the vagina after each menstrual period, or monthly. Patients should be told NOT to pull on the threads. Their partners should be instructed likewise.
Patients should be counseled to contact their health care provider under the following circumstances:
• if they can’t feel the threads or they feel more of the system than just the threads. This may indicate the system is not in the proper position;
• if they believe, because of a missed menstrual period or for any reason, they may be pregnant (note: even if clinicians are not concerned regarding the possibility of pregnancy, users may find negative urine pregnancy tests to be highly reassuring);
• if they experience pelvic pain or pain during intercourse (which suggests perforation or infection);
• if they develop unusual vaginal discharge;
• if they have unexplained fever (which suggests infection);
• if they develop very severe or migraine headaches;
• if they develop jaundice;
• if they experience severe or prolonged vaginal bleeding (which suggests dislocation or perforation);
Removal
To remove the LNG IUS, use forceps to apply gentle traction on the threads. This will cause the arms of the system to fold upward as the IUS is withdrawn from the uterus. A new LNG IUS or other IUD may be inserted immediately after removal of a used system. If a patient with regular cycles wants to use a different method of contraception after removal of the LNG IUS, remove the system during the first seven days of the menstrual cycle and instruct her to start the new method immediately. If the system is removed after the seventh day of the menstrual cycle, or the patient has irregular cycles or amenorrhea and wants to switch to a different method, her new contraceptive should be initiated at least seven days prior to removal of the system.25
Summary
Because the LNG IUS provides safe, highly effective, convenient, and reversible contraception, its availability in the United States should increase the number of women using modern effective birth control. Candid counseling of LNG IUS candidates regarding contraceptive selection and close attention to insertion technique, as described in this review, should enhance users’
success with this new method. The noncontraceptive benefits provided by the LNG IUS should further expand the number of U.S. women who will benefit from this innovative system.
References
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20. Anonymous editorial. Does infection occur with modern intrauterine devices? Lancet 1992; 339:783-784.
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24. Walsh T, Grimes D, Frezieres R, et al. Randomised controlled trial of prophylactic antibiotics before insertion of intrauterine devices. IUD Study Group. Lancet 1998; 351:1,005-1,008.
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31. Sivin I. IUDs and ectopic pregnancy. Stud Fam Plann 1983; 14:57-63.
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35. Lahteenmaki P, Haukkamaa M, Puolakka J, et al. Open randomised study of use of levonorgestrel releasing intrauterine system as alternative to hysterectomy. Br Med J 1998; 316:1,122-1,126.
36. Farquhar CM. Management of dysfunctional uterine bleeding. Drugs 1992; 44:578-584.
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38. Suhonen S, Holmstrom T, Lahteenmaki P. Three-year follow-up of the use of a levonorgestrel releasing intrauterine system in hormone replacement therapy. Acta Obstet Gynecol Scand 1997; 76:145-150.
39. Raudaskoski TH, Lahti EI, Kauppila AJ, et al. Transdermal estrogen with a levonorgestrel-releasing intrauterine device for climacteric complaints: Clinical and endometrial responses. Am J Obstet Gynecol 1995; 172:114-119.
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CME Question
To earn CME credit for this issue of Contraceptive Technology Reports, please refer to the enclosed Scantron form for directions on taking the test and submitting your answer.
1. For how many years of contraceptive use is the LNG IUS is approved?
A. three years
B. five years
C. seven years
D. 10 years
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