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Combined hormonal contraception during high-altitude trekking — DFSRH MCQ

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EasyAltitudeCombined hormonal contraception during high-altitude trekkingDFSRH

A 28-year-old woman seeks contraceptive advice before an 18-day mountaineering expedition. The itinerary includes 9 consecutive nights sleeping at 4700–5200 m. She uses a combined oral contraceptive containing ethinylestradiol and drospirenone and wishes to maintain effective contraception throughout the trip. She is a non-smoker with a BMI of 23 kg/m² and has no personal or family history of venous thromboembolism or thrombophilia. She will usually be active, although adverse weather could confine the group to camp for several days. She is medically eligible for oestrogen-free contraception. Which is the most appropriate contraceptive advice?

Educational content. Not a substitute for clinical judgement or local policy.

Reveal the answer and explanation

Correct answer: D — Switch before departure to a suitable oestrogen-free contraceptive method

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

FSRH advises considering avoidance of combined hormonal contraception when a woman will spend more than 1 week above 4500 m. This itinerary exceeds both elements of that threshold: she will spend 9 consecutive nights at 4700–5200 m. Switching before departure to an effective oestrogen-free method therefore avoids the additional thrombotic contribution from CHC while maintaining contraception. High-altitude exposure increases erythropoiesis, while hypoxia, dehydration, low temperature and possible enforced immobility may further promote thrombosis. The supporting evidence is limited and the recommendation is based substantially on expert opinion, but it is directly applicable to this planned exposure. A is incorrect because aspirin is not recommended as a substitute for modifying contraceptive risk. B is attractive because FSRH considers CHC likely to be safe below the stated threshold in a healthy, active, non-smoking woman without thrombosis history; however, this expedition exceeds the altitude and duration threshold. C is incorrect because compression stockings do not remove the oestrogen-related risk and evidence does not support relying on them to permit continued CHC. E would reduce baseline VTE risk relative to a drospirenone COC, but levonorgestrel-containing preparations remain combined hormonal contraceptives and do not address the high-altitude recommendation.

Reference: FSRH Guideline: Combined Hormonal Contraception — section 14.2, CHC use at high altitude (January 2019; amended October 2023) — https://www.fsrh.org/Common/Uploaded%20files/documents/fsrh-guideline-combined-hormonal-contraception-october-2023.pdf FSRH Guideline: Combined Hormonal Contraception — sections 14.1 and 14.2 (January 2019; amended October 2023) — https://www.fsrh.org/Common/Uploaded%20files/documents/fsrh-guideline-combined-hormonal-contraception-october-2023.pdf