Intrauterine System

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PatientPlus articles are written by UK doctors and are based on research evidence, UK and European Guidelines. They are designed for health professionals to use, so you may find the language more technical than the condition leaflets.

See also: Intrauterine System written for patients

This article refers to the intrauterine system (IUS). For information on the copper-containing (non-hormonal) intrauterine device see the separate article Intrauterine Contraceptive Device (IUCD). For information on insertion techniques see the separate article Intrauterine Contraceptives (IUCD and IUS) - Management.

The IUS is an intrauterine contraceptive which releases levonorgestrel (LNG). Mirena® is the LNG-releasing IUS that has been available in the UK since 1995. It has a plastic T-shaped frame with a reservoir containing 52 mg of LNG and releasing 20 micrograms/24 hours at outset.[1] The Mirena® IUS has also been licensed more recently for the treatment of idiopathic menorrhagia and as endometrial protection for those receiving oestrogen hormone replacement therapy.[2] 

Jaydess® has become available for use this year.[3] It is very similar to Mirena® but has some key differences; the frame is smaller and narrower and the reservoir only contains 13.5 mg of LNG.The Jaydess® IUS is effective for three years and only has a licence for contraception.

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  • The LNG-IUS (and other methods of long-acting reversible contraception (LARC)) is more cost-effective than the combined oral contraceptive pill (COCP) even at one year of use.[4]
  • It is also more cost-effective than injectable contraceptives.
  • In the past, doctors have been reluctant to fit LNG-IUS devices on the basis of item cost but cost-effectiveness analyses show this to be a false saving when other costs are taken into account.
  • Jaydess® is cheaper per device than Mirena® (£69.22 vs £88) but only lasts three years.
  • In the treatment of heavy menstrual periods the IUS is significantly more cost-effective than endometrial ablation or hysterectomy.[5]
  • The National Institute for Health and Care Excellence (NICE) advises that increasing the uptake of LARC methods will reduce the numbers of unintended pregnancies. It is important that women should be advised of LARC methods when seeking contraception.
  • At present only 2-3% of contraception-using women use the IUS as their method of choice. This has increased only slowly over the last few years despite its benefits.
  • The primary contraceptive effect is mediated by its suppressant effect on the endometrium, which prevents implantation: within one month of insertion high intrauterine LNG levels cause endometrial atrophy, changes in the stroma.
  • There is an increase in endometrial phagocytic cells which also prevents implantation.
  • Decreased sperm penetration of cervical mucus and impaired sperm migration.
  • There is little effect on the hypothalamic-pituitary-ovarian axis: oestrogen levels are not reduced and most women continue to ovulate.
  • Amenorrhea with the IUS does not reliably indicate anovulation.
  • Failure rates are very low, at 1-2% over five years of use: a Cochrane review found failure rates to be similar as for the TCu380A but World Health Organization (WHO) data suggest the IUS may be more effective at five years of use.
  • The failure rate is also affected by sexual activity, age and parity.[6] 
  • The Mirena® IUS is licensed for contraceptive use for a period of five years from insertion
  • The Mirena® IUS is also licensed for five years for idiopathic menorrhagia and for four years to provide endometrial protection
  • Randomised controlled trials (RCTs) suggest that it provides contraceptive protection for up to seven years
  • The Clinical Effectiveness Unit (CEU) has recommended a seven-year duration of use for women aged 45 years or over at the time of insertion.
  • The LARC guideline recommends that women who have the LNG-IUS inserted at or after the age of 45 years and are amenorrhoeic may retain the LNG-IUS until the menopause.[4] 
  • Jaydess® is licensed for contraception alone, for a period of three years.
  • The Mirena® coil and Jaydess coil® are LNG-IUS currently available in the UK.

Contraceptive use

  • The LNG-IUS is a suitable option for most women who need contraception, with few conditions where risks of use outweigh benefits (see 'Contra-indications and cautions', below).
  • Its niche to date has been as contraception for multiparous women with heavy periods.
  • It can be appropriate for many other women, including those who traditionally offer contraceptive challenge, such as obese women, women with diabetes or epilepsy, women with migraine and women with contra-indications to oestrogen (see separate article Contraception and Special Groups).[4]
  • The LNG-IUS should not be used as emergency contraception (see separate article Emergency Contraception).

Advantages as a contraceptive method
These include:

  • Rapid return of fertility post-removal.
  • Reduced menstrual loss and dysmenorrhoea.
  • Convenience (long-lasting method that is independent of intercourse).
  • Lack of significant interactions with hepatic enzyme-inducing drugs.
  • Compared to long-acting injectable depot contraceptives there is no demonstrable effect on bone mineral density (BMD), with users' BMDs comparable to non-users' after seven years of use.[7]

Disadvantages as a contraceptive method
These include:

  • Initial menstrual irregularities.
  • Other side-effects (see 'Side-effects', below).
  • Fitting an IUS is technically more difficult (in view of its larger diameter) than fitting an IUCD, particularly in nulliparous or perimenopausal women. However, Jaydess® may be fitted more easily, as the frame is smaller and narrower.

Non-contraceptive uses

Menorrhagia

  • The Mirena® LNG-IUS is the first-line pharmaceutical treatment for menorrhagia (where hormonal methods are acceptable and ongoing treatment of at least a year is anticipated) and can reduce menstrual losses by over 90%.[2]
  • It is effective even in the presence of fibroids, although it is not generally recommended where fibroids distort the uterine cavity, because of difficulties with insertion.
  • The Mirena® LNG-IUS is more effective than medical treatments for the treatment of menorrhagia. A recent meta-analysis showed its superior efficacy to oral progestogens for the treatment of idiopathic menstrual blood loss.[8]
  • A Cochrane review found that surgical treatment (hysterectomy, endometrial resection or ablation) is more effective at reducing menstrual blood loss at one year but the LNG-IUS is as effective at improving quality of life at one year.[9] Therapeutic results are comparable at two years for endometrial ablation.[10]
  • There is some suggestion that sexual function is better post-hysterectomy for women with menorrhagia than for those treated with an LNG-IUS.[11][12]
  • Cost of treatment for menorrhagia is significantly lower in women with LNG-IUS compared with hysterectomy.[13]

Hormone replacement therapy (HRT)

  • The Mirena® LNG-IUS is licensed for the prevention of endometrial hyperplasia during oestrogen replacement therapy.
  • It provides a means of delivering endometrial protection with minimum systemic absorption of progestogen.
  • One RCT showed that a 10 micrograms/24 hours IUS (not currently available) was as effective as the Mirena® in providing endometrial protection in postmenopausal women on oestrogen therapy but had the advantage of easier insertion and less effect on serum lipid profiles.[14]

Future uses
Other potential uses of the Mirena® IUS include its role in the treatment of:

  • Endometriosis and adenomyosis - studies have looked at the use of the LNG-IUS as maintenance therapy or following surgery: there is some evidence that the IUS is effective in treating pain in these conditions.[15][16]
  • Endometrial hyperplasia - the IUS appears effective as a treatment for non-atypical endometrial hyperplasia.[17][18]
  • Endometrial protection for women on tamoxifen - the IUS provides endometrial protection from tamoxifen-induced changes.[19] However, a Cochrane review concluded that in view of concerns around the stimulatory effect of progesterone on breast cancers, further evidence was needed.[20]
  • Early-stage endometrial carcinoma - the IUS may have a role in a patient unfit for surgery.[21]

Absolute contra-indications

There are few absolute evidence-based contra-indications and they fall into five categories: infection, pregnancy, uterine factors, gynaecological cancers and contra-indications to LNG.[6] 

  • Infection:
    • History of pelvic inflammatory disease (PID) or purulent cervicitis, although it may be inserted three months after infection, if there are no signs of persisting infection.
    • Recent exposure to sexually transmitted infection.
    • Septic abortion or postpartum endometritis in the previous three months.
    • Pregnancy.
  • Pregnancy:
    • Current pregnancy.
    • Between 48 hours and four weeks postpartum. World Health Organization (WHO) medical eligibility criteria state that risks generally outweigh benefits if postpartum insertion occurs between 48 hours and four weeks.[22] Beyond four weeks postpartum, benefits outweigh risks, even if the woman is breast-feeding.
  • Uterine factors:
    • Uterine abnormality distorting the uterine cavity - eg, fibroids, bicornuate uterus. This is mainly due to difficulties with insertion.
    • Uterus less than 5.5 cm in length on sounding: the device may be expelled, but may also be less effective (eg, if placed in one horn of bicornuate uterus).
  • Gynaecological cancers:
    • Ovarian, cervical, breast or endometrial cancer.
    • Malignant trophoblastic disease.
    • Undiagnosed irregular vaginal bleeding/suspicion of genital malignancy.
    • Adverse reactions to copper.
  • Contra-indications to LNG:
    • Current deep vein thrombosis (DVT) or pulmonary embolus (PE).
    • Ischaemic heart disease.
    • Active viral hepatitis, severe decompensated cirrhosis, benign liver tumours or malignant hepatomas.
    • Breast cancer within the preceding five years.
  • Other:
    • Previous history of bacterial endocarditis after prosthetic valve replacement.
    • Significant immunosuppression.

Relative contra-indications - usable with caution

  • Nulliparous, young age (see below).
  • Definite history of pelvic infection.
  • High risk of STI.
  • Known HIV infection.
  • Structural heart disease, with risk of endocarditis. The American Heart Association and NICE recommend discussion with the patient's own cardiologist but do not routinely recommend the use of antibiotic prophylaxis for genitourinary procedures.[23][24] 
  • History of ectopic pregnancy.
  • The patient has a prosthesis which could be compromised by blood-borne infection.
  • Two days to four weeks postpartum.
  • Benign trophoblastic disease.
  • Severe cervical stenosis.
  • Fibroids or congenital abnormality of the uterus, but no marked distortion of the cavity.
  • After endometrial ablation or resection.
  • Between 48 hours and four weeks post-termination: the chances of expulsion post-insertion are slightly increased in this period. It is recommended that the IUCD/IUS should only be inserted at this time if the patient is at risk of pregnancy and finds no other method acceptable, and the operator is experienced.[6] 

Use in nulliparous women

  • Studies suggest that insertion of the device is well tolerated in nulliparous women with comparable rates of insertion failure and operator difficulty as for parous women.[25] 

For complications associated directly with the insertion process, including perforation, expulsion and lost threads, see separate article Intrauterine Contraceptives (IUCD and IUS) - Management.

Altered or abnormal bleeding

Irregular bleeding and spotting are common in the first six months with an LNG-IUS. Counsel women that 65% of women develop amenorrhoea with the Mirena® IUS and 90% experience reduced menstrual flow ultimately. Guidance for unscheduled bleeding suggests:[26]

  • <3 months from insertion - exclude STIs, check cervical screening history and consider the need for a pregnancy test. Where pain, discharge or lost threads occur in addition to bleeding, this requires further investigation to exclude expulsion, perforation or infection.
  • >3 months from insertion (although the guidance notes that IUS-related bleeding is common up to six months) - perform a clinical examination where there is persistent bleeding, any new symptom or changed bleeding pattern, failed medical treatment, non-participation in the cervical screening programme or if requested by the woman. Abnormal clinical findings should be managed appropriately. Where findings are normal, but the woman is aged over 45 years or has risk factors for endometrial cancer, refer for further investigation (eg, ultrasound, hysteroscopy, endometrial biopsy).

Bleeding due to the IUS may settle spontaneously within six months. Alternatively, a three-month trial of a first-line COCP may be considered, although this is an off-licence use. Where bleeding is not improving, refer at six months or, if there is menstrual flooding, remove the LNG-IUS, as its mechanical presence may be the cause.[27]

  • Prior to commencing use of the IUS, women should be counselled that altered patterns of menstrual bleeding are common - irregular bleeding and spotting (common in the first six months of treatment) and amenorrhoea in particular.
  • Up to 60% of women stop using the Mirena® LNG-IUS within five years - the most common reason is unacceptable vaginal bleeding.
  • Amenorrhoea is reported in 65% of women using the Mirena® LNG-IUS after one year (this is less lkely with Jaydess®) and is perceived by many as a benefit.[4]

Hormonal symptoms

  • Acne, headaches, breast tenderness and nausea are reported by LNG-IUS users but these do not differ significantly from IUCD users.
  • Serum LNG levels with an IUS are lower than with oral or subdermal administration of progestogen but there is wide individual difference, possibly explaining the variation in experience of hormonal side-effects.

Pregnancy and ectopic pregnancy

  • Overall, rates are lower than with no contraception.
  • If a woman does become pregnant with an LNG-IUS in situ, ectopic pregnancy risk is 1 in 20, so she should seek medical advice to exclude it.
  • The risk of ectopic pregnancy is less for LNG-IUS than for conventional IUCDs.
  • Ectopic pregnancy must be excluded although most pregnancies will be intrauterine.
  • Ectopic pregnancy is increased relative to normal pregnancies where copper devices are used. However, there is no absolute increase in risk.
  • Women who become pregnant must be counselled regarding the increased risk of second-trimester miscarriage, infection and preterm delivery if the device remains in situ, and that removal reduces these outcomes but is associated with a small risk of miscarriage
  • If threads are visible or retrievable in the endocervical canal the device should be removed up to 12 weeks of gestation.
  • In other cases the device should be sought at delivery or termination and, if not detected at this time, an abdominal X-ray performed to ensure it is not extrauterine.

Pelvic infection

  • This is most strongly related to the insertion procedure and to the background risk of STIs.
  • There is a six-fold increase in risk of PID in the first 20 days following insertion.
  • If pelvic infection is suspected in a woman using an IUCD/IUS then antibiotics should be started.
  • The device does not need to be removed unless symptoms fail to resolve within 72 hours.
  • Women should be followed up and their partners treated where appropriate. Sexual health risk assessment and counselling should be offered.

Actinomyces-like organisms (ALOs)

  • ALOs are commensals of the female genital tract and have been identified in women with and without intrauterine contraception
  • Their role in infection in women using intrauterine contraception is not clear
  • If ALOs are seen on a swab or smear, removal of the device is not indicated if the woman is asymptomatic.
  • If symptoms of pelvic pain occur in conjunction with the presence of ALOs, other causes of infection should be considered and removal of the device may be advisable.

Evidence suggests that the IUS does not delay return to fertility after removal.[6] It can, however, take some months for regular menses to resume.

Where pregnancy is desired

  • The LNG-IUS can be removed at any time.

Where pregnancy is not desired

  • The LNG-IUS should be removed with menstruation or, if there has been no unprotected sexual intercourse in the previous seven days, at other times.
  • Where the LNG-IUS is to be exchanged, intercourse should be avoided for the previous seven days in case re-insertion fails.
  • Where removal is at the end of the licensed duration of use: remove at any time in the menstrual cycle. If pregnancy is to be avoided, remove in the first few days after the onset of menstruation or advise condoms or abstinence from sexual intercourse for at least seven days before the procedure in case re-insertion is not possible.
  • When switching to the COCP, remove after seven consecutive pills.
  • When switching to the depot or implant progestogen methods, remove the LNG-IUS after seven days of use of the new method.

Postmenopausal removal

  • If inserted after the age of 45 years the IUS can continue to be used for contraception for seven years
  • If the LNG-IUS is being used in the management of menorrhagia (and not for contraception or with oestrogen replacement therapy) it can be retained beyond the five-year licensed duration of use if bleeding patterns are acceptable.
 

IUCD - gold standard is the banded T-safe copper 380A.

IUS

Method of action

Prevents fertilisation and inhibits implantation.

Prevents implantation mainly.
Duration of action

5-10 years if contains 380 mm copper.

Until contraception is no longer required.

Mirena® - five years or until contraception is no longer required.

Jaydess® - three years.

Failure rate

1-2% over five years for most devices.[6] 

Evidence suggests that the latest copper-banded IUCDs are better than the COCP and as effective as sterilisation.

Expulsion in less than 1 woman in 20 per five years.

Risks

PID incidence is less than 1% if low risk for STI.

Perforation incidence is less than 1 per 1,000.

Ectopic pregnancy risk is 1 in 20, if pregnant with IUCD in situ.

60% request removal within five years, due to bleeding, pain or hormonal problems.

PID risk is less than 1%, if low risk for STI.

Perforation risk is less than 1 per 1,000.

Ectopic pregnancy risk is 1 in 20, if pregnant with IUS in situ.

Query increased risk of acne.

Effect on mensesIncreased menstrual loss and dysmenorrhoea.

Irregular bleeding and spotting for the first six months.

Oligomenorrhoea or amenorrhoea likely if persisting for one year.

Reduced likelihood of amenorrhoea with Jaydess®.

Return to fertilityNo delay.No delay.
Advice given at fitting

Pain and discomfort last a few hours, followed by light bleeding for a few days.

Watch for signs of perforation.

Follow-up in 3-6 weeks.

Return if concerned.

Check threads.

Pain and discomfort last a few hours, followed by light bleeding for a few days.

Watch for signs of perforation.

Follow-up in 3-6 weeks.

Return if concerned.

Check threads.

Further reading & references

  1. Summary of Product Characteristics (SPC) - Mirena®; Bayer plc, electronic Medicines Compendium
  2. Heavy menstrual bleeding; NICE Clinical Guideline (January 2007)
  3. Jaydess Levonorgestrel intrauterine system - New product review; Clinical Effectiveness Unit of the Faculty of Sexual and Reproductive Healthcare (2014)
  4. Long-acting reversible contraception; NICE Clinical Guideline (October 2005)
  5. Clegg JP, Guest JF, Hurskainen R; Cost-utility of levonorgestrel intrauterine system compared with hysterectomy and second generation endometrial ablative techniques in managing patients with menorrhagia in the UK. Curr Med Res Opin. 2007 Jul;23(7):1637-48.
  6. Intrauterine Contraception; Faculty of Sexual and Reproductive Healthcare (2007)
  7. Bahamondes L, Espejo-Arce X, Hidalgo MM, et al; A cross-sectional study of the forearm bone density of long-term users of levonorgestrel-releasing intrauterine system. Hum Reprod. 2006 May;21(5):1316-9. Epub 2005 Dec 22.
  8. Kaunitz AM, Bissonnette F, Monteiro I, et al; Levonorgestrel-releasing intrauterine system or medroxyprogesterone for heavy Obstet Gynecol. 2010 Sep;116(3):625-32.
  9. Marjoribanks J, Lethaby A, Farquhar C; Surgery versus medical therapy for heavy menstrual bleeding. Cochrane Database Syst Rev. 2006 Apr 19;(2):CD003855.
  10. Kaunitz AM, Meredith S, Inki P, et al; Levonorgestrel-releasing intrauterine system and endometrial ablation in heavy Obstet Gynecol. 2009 May;113(5):1104-16.
  11. Halmesmaki K, Hurskainen R, Teperi J, et al; The effect of hysterectomy or levonorgestrel-releasing intrauterine system on sexual functioning among women with menorrhagia: a 5-year randomised controlled trial. BJOG. 2007 May;114(5):563-8.
  12. Heliovaara-Peippo S, Halmesmaki K, Hurskainen R, et al; The effect of hysterectomy or levonorgestrel-releasing intrauterine system on BJOG. 2010 Apr;117(5):602-9. Epub 2010 Feb 15.
  13. Hurskainen R, Teperi J, Rissanen P, et al; Clinical outcomes and costs with the levonorgestrel-releasing intrauterine system or hysterectomy for treatment of menorrhagia: randomized trial 5-year follow-up.; JAMA. 2004 Mar 24;291(12):1456-63.
  14. Raudaskoski T, Tapanainen J, Tomas E, et al; Intrauterine 10 microg and 20 microg levonorgestrel systems in postmenopausal women receiving oral oestrogen replacement therapy: clinical, endometrial and metabolic response.; BJOG. 2002 Feb;109(2):136-44.
  15. Wong AY, Tang LC, Chin RK; Levonorgestrel-releasing intrauterine system (Mirena) and Depot Aust N Z J Obstet Gynaecol. 2010 Jun;50(3):273-9.
  16. Abou-Setta AM, Al-Inany HG, Farquhar CM; Levonorgestrel-releasing intrauterine device (LNG-IUD) for symptomatic Cochrane Database Syst Rev. 2006 Oct 18;(4):CD005072.
  17. Buttini MJ, Jordan SJ, Webb PM; The effect of the levonorgestrel releasing intrauterine system on endometrial Aust N Z J Obstet Gynaecol. 2009 Jun;49(3):316-22.
  18. Varma R, Soneja H, Bhatia K, et al; The effectiveness of a levonorgestrel-releasing intrauterine system (LNG-IUS) in the treatment of endometrial hyperplasia-A long-term follow-up study. Eur J Obstet Gynecol Reprod Biol. 2008 Aug;139(2):169-75. Epub 2008 Apr 28.
  19. Gardner FJ, Konje JC, Abrams KR, et al; Endometrial protection from tamoxifen-stimulated changes by a levonorgestrel-releasing intrauterine system: a randomised controlled trial. Lancet. 2000 Nov 18;356(9243):1711-7.
  20. Chin J, Konje JC, Hickey M; Levonorgestrel intrauterine system for endometrial protection in women with Cochrane Database Syst Rev. 2009 Oct 7;(4):CD007245.
  21. Varma R, Sinha D, Gupta JK; Non-contraceptive uses of levonorgestrel-releasing hormone system (LNG-IUS)--a systematic enquiry and overview. Eur J Obstet Gynecol Reprod Biol. 2006 Mar 1;125(1):9-28. Epub 2005 Dec 1.
  22. Medical eligibility criteria for contraceptive use, 4th edition; World Health Organization, 2009
  23. Wilson W, Taubert KA, Gewitz M, et al; Guidelines for the prevention of infective endocarditis: : a guideline from the American Heart Association J Am Dent Assoc. 2007 Jun;138(6):739-45, 747-60.
  24. Prophylaxis against infective endocarditis: Antimicrobial prophylaxis against infective endocarditis in adults and children undergoing interventional procedures; NICE Clinical Guideline (March 2008)
  25. Marions L, Lovkvist L, Taube A, et al; Use of the levonorgestrel releasing-intrauterine system in nulliparous women--a non-interventional study in Sweden. Eur J Contracept Reprod Health Care. 2011 Apr;16(2):126-34. doi: 10.3109/13625187.2011.558222.
  26. Management of Unscheduled Bleeding in Women Using Hormonal Contraception; Faculty of Sexual and Reproductive Healthcare (2009)
  27. Ronnerdag M, Odlind V; Late bleeding problems with the levonorgestrel-releasing intrauterine system: evaluation of the endometrial cavity. Contraception. 2007 Apr;75(4):268-70. Epub 2007 Jan 26.

Disclaimer: This article is for information only and should not be used for the diagnosis or treatment of medical conditions. EMIS has used all reasonable care in compiling the information but make no warranty as to its accuracy. Consult a doctor or other health care professional for diagnosis and treatment of medical conditions. For details see our conditions.

Original Author:
Dr Chloe Borton
Current Version:
Peer Reviewer:
Prof Cathy Jackson
Document ID:
523 (v9)
Last Checked:
18/08/2014
Next Review:
17/08/2019

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