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Progestogen-Only Intrauterine Device Pregnancy: Remove if pregnancy occurs with IUS in situ (increased ectopic and miscarriage risk); not teratogenic — LNG-IUS pregnancy outcomes good if device removed early

Levonorgestrel Intrauterine System

Brand names: Mirena (52 mg), Kyleena (19.5 mg), Jaydess (13.5 mg)

Adult dose

Dose: Mirena: 52 mg LNG (releases 20 mcg/day); Kyleena: 19.5 mg (releases 9 mcg/day); Jaydess: 13.5 mg (releases 6 mcg/day)
Route: Intrauterine (inserted by trained clinician)
Frequency: Single insertion; Mirena licensed 5–8 years (HMB/HRT); Kyleena 5 years; Jaydess 3 years
Max: Single device at a time
Mirena 52 mg: first-line HMB treatment (NICE NG88), endometriosis, HRT progestogen component; Kyleena: contraception with lighter periods; Jaydess: contraception, lowest systemic LNG

Paediatric dose

Dose: Not applicable N/A/kg
Route: N/A
Frequency: N/A
Max: N/A
Adolescent use possible for HMB/dysmenorrhoea — specialist insertion

Dose adjustments

Renal

No adjustment — minimal systemic absorption

Hepatic

Avoid in active severe liver disease; minimal systemic LNG at standard IUS doses

Paediatric weight-based calculator

Adolescent use possible for HMB/dysmenorrhoea — specialist insertion

Clinical pearls

  • NICE NG88 (HMB 2018): Mirena LNG-IUS is first-line treatment for HMB — superior to oral tranexamic acid, norethisterone, and NSAIDs; reduces blood loss by ~90% at 12 months; recommended before considering surgical options
  • Mirena licensed for use as progestogen arm of HRT in women with intact uterus — single Mirena provides endometrial protection for up to 5 years (4 years in NICE guidance) when combined with systemic oestrogen; avoids oral progestogen side effects
  • Insertion: most comfortable during menstruation when cervix is softer; misoprostol 400 mcg PV 1-4 hours before insertion recommended for nulliparous women to soften cervix — reduces pain and failed insertion rate
  • Thread check: women should check threads monthly; if absent, consider expulsion or perforation — ultrasound or X-ray to locate device; pregnancy must be excluded
  • Mirena vs oral norethisterone for HMB (NEJM 2013, Gupta et al.): LNG-IUS significantly more effective at reducing menstrual blood loss and improving quality of life at 2 years vs cyclical norethisterone; also associated with higher patient satisfaction

Contraindications

  • Current pelvic inflammatory disease
  • Unexplained abnormal uterine bleeding
  • Uterine abnormality distorting cavity
  • Cervical/endometrial malignancy
  • Gestational trophoblastic disease (elevated hCG)
  • Allergy to levonorgestrel

Side effects

  • Irregular bleeding/spotting (first 3-6 months)
  • Amenorrhoea (50% at 1 year — desired outcome for HMB)
  • Hormonal side effects rare (low systemic absorption)
  • Expulsion (4-5%)
  • Perforation at insertion (1/1000)
  • Ovarian cysts (functional — usually resolve)

Interactions

  • Enzyme inducers (rifampicin, anticonvulsants) — may reduce contraceptive efficacy; UKMEC recommends additional contraception or alternative
  • Ulipristal (EC use) — avoid progestogen within 5 days of ulipristal EC

Monitoring

  • Thread check at 6-week post-insertion review
  • Annual pelvic examination
  • Pregnancy test if amenorrhoea with no threads palpable
  • Ovarian cysts (USS if pelvic pain develops)

Reference: BNFc; BNF 90; NICE NG88 (HMB 2018); Gupta et al. NEJM 2013 (LNG-IUS vs norethisterone for HMB); FSRH Intrauterine Contraception Guideline (2023); SPC Mirena; UKMEC 2016. Verify against your local formulary and the latest BNF before prescribing.

Related

Curated clinical cross-links plus same-class fallbacks.

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