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Iron-deficiency anaemia after Roux-en-Y gastric bypass — DFSRH MCQ

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EasyAnaemiaIron-deficiency anaemia after Roux-en-Y gastric bypassDFSRH

A 31-year-old woman requests contraception 9 months after a Roux-en-Y gastric bypass. Her BMI has fallen from 43 kg/m² to 32 kg/m², and her previously irregular cycles are now monthly. She has persistent iron-deficiency anaemia despite adherence to oral iron (haemoglobin 94 g/L, ferritin 5 micrograms/L) and is awaiting intravenous iron, with no gastrointestinal bleeding or heavy menstruation identified. Her bariatric team has advised avoiding pregnancy until at least 18 months after surgery. She wishes to start trying to conceive promptly thereafter. She declines intrauterine contraception but would accept an implant, injection, pill, patch or vaginal ring. Pregnancy is reasonably excluded, and she takes no interacting medication. Which contraceptive method is most appropriate?

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Correct answer: C — Initiate an etonogestrel subdermal implant

The etonogestrel implant is the best fit because it combines two decisive requirements: highly effective contraception during the first 18 months after bariatric surgery and avoidance of potentially unreliable gastrointestinal absorption. Her persistent iron deficiency despite oral replacement reinforces that clinically relevant malabsorption is ongoing. FSRH advises considering the most effective long-acting reversible methods within 2 years of bariatric surgery and recommends non-oral contraception because oral contraceptive effectiveness may be reduced. Implant effectiveness is not reduced by raised BMI. The desogestrel pill is attractive because it contains no oestrogen, but evidence is insufficient regarding POP effectiveness after bariatric surgery. The combined oral contraceptive is also absorption-dependent and is therefore less appropriate. The vaginal ring avoids gastrointestinal absorption and could be used by a medically eligible patient, but it remains user-dependent and is less reliable in typical use than the implant during this high-consequence interval. Depot medroxyprogesterone acetate is non-oral and effective, but it may substantially delay return to fertility after the final injection, conflicting with her intention to attempt conception promptly at 18 months. Her iron-deficiency anaemia does not contraindicate the implant; rather, its presence helps identify ongoing post-bypass malabsorption and strengthens the case against oral methods.

Reference: FSRH Guideline: Overweight, Obesity and Contraception (April 2019) — https://www.fsrh.org/Common/Uploaded%20files/documents/1overweight-obesity-and-contraception-guideline-april-2019.pdf FSRH Guideline: Progestogen-only Pills (August 2022, amended July 2023) — https://www.fsrh.org/Common/Uploaded%20files/documents/fsrh-ceu-clinical-guideline-progestogen-only-pills-aug22-amended-11july-2023-.pdf FSRH Guideline: Progestogen-only Implant (February 2021, amended July 2023) — https://www.fsrh.org/Common/Uploaded%20files/documents/fsrh-guideline-progestogen-only-implants.pdf