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Established osteoporosis with enzyme-inducing antiseizure therapy and heavy menstrual bleeding — DFSRH MCQ

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HardBone Mineral DensityEstablished osteoporosis with enzyme-inducing antiseizure therapy and heavy menstrual bleedingDFSRH

A 35-year-old woman requests highly effective reversible contraception. She takes long-term carbamazepine for focal epilepsy; seizure control is good and her neurologist does not plan to change treatment. Following a low-trauma distal radial fracture, specialist assessment and DXA confirmed premenopausal osteoporosis with a lumbar-spine Z-score of −2.8. Secondary causes have been addressed. She also has regular heavy menstrual bleeding that substantially affects her quality of life. She has no intermenstrual bleeding or pelvic pain. Examination and transvaginal ultrasonography show a normal uterus and no endometrial or myometrial pathology. Pregnancy is reasonably excluded, and she has no contraindication to intrauterine contraception. She would prefer a method likely to reduce menstrual bleeding. Which contraceptive method is most appropriate?

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Reveal the answer and explanation

Correct answer: B — 52 mg levonorgestrel intrauterine device

Explanation lettering: D = shown as A · C = shown as B · B = shown as C · A = shown as D

The 52 mg levonorgestrel intrauterine device (LNG-IUD) best integrates three competing considerations. First, carbamazepine induces hepatic enzymes and may reduce the effectiveness of combined hormonal contraception and the etonogestrel implant; the locally acting LNG-IUD is unaffected. Second, established osteoporosis makes DMPA a less appropriate choice: although enzyme induction does not compromise its contraceptive efficacy and amenorrhoea may improve bleeding, DMPA suppresses ovarian oestrogen and is associated with BMD loss. FSRH advises considering alternative methods in those with significant osteoporosis risk factors. Third, an LNG-IUD is recommended first-line for heavy menstrual bleeding without identified pathology and limited evidence suggests that intrauterine contraception has no significant effect on BMD. A is unreliable with ongoing enzyme induction. B is an attractive near-miss because it is interaction-resistant and may suppress menstruation, but an equally effective, bone-neutral option is available. D is also unaffected by carbamazepine and bone-neutral, but commonly increases menstrual blood loss. E may reduce bleeding and higher-dose ethinylestradiol regimens can exceptionally be considered with some enzyme inducers after specialist advice; however, efficacy is less dependable than an unaffected intrauterine method and it is not the best available option here.

Reference: FSRH Clinical Guidance: Drug Interactions with Hormonal Contraception (May 2022) — https://www.fsrh.org/Common/Uploaded%20files/documents/drug-interactions-with-hormonal-contraception-5may2022.pdf FSRH Clinical Guidance: Progestogen-only Injectable Contraception (December 2014; amended July 2023) — https://www.fsrh.org/Common/Uploaded%20files/documents/progestogen-only-injectable-december-2014-amended-11july2023.pdf FSRH Guideline: Intrauterine Contraception (March 2023; amended January 2025) — https://www.fsrh.org/Common/Uploaded%20files/documents/fsrh-clinical-guideline-intrauterine-contraception-mar-23-amended.pdf