skip to main content

Hereditary angioedema due to C1-inhibitor deficiency — DFSRH MCQ

Instant feedback + full explanation. One question, done properly.

HardImmunologyHereditary angioedema due to C1-inhibitor deficiencyDFSRH

A 30-year-old woman with genetically confirmed type I hereditary angioedema due to C1-esterase inhibitor deficiency requests contraception. Her attacks consist of non-pruritic facial or abdominal swelling without urticaria. Following a cervical biopsy 2 years ago, she developed laryngeal oedema that did not improve with adrenaline, an antihistamine or a corticosteroid but resolved after icatibant. She is not receiving long-term prophylaxis and carries icatibant for on-demand treatment. She has heavy, painful menstruation with a haemoglobin of 105 g/L and ferritin of 8 micrograms/L. Pelvic ultrasonography shows no pathology and a normal uterine cavity. She wants highly effective, user-independent, reversible contraception that is likely to reduce menstrual bleeding. She is on day 3 of a normal menstrual period, has had no intercourse since it began, and has a negative pregnancy test. There is no genital infection or other method-specific contraindication to intrauterine contraception. Which is the most appropriate contraceptive plan?

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

Reveal the answer and explanation

Correct answer: C — Insert a 52 mg levonorgestrel intrauterine device under a specialist plan including pre-procedure C1-inhibitor and access to on-demand treatment

Hereditary angioedema due to C1-inhibitor deficiency is bradykinin-mediated, as indicated by swelling without urticaria and failure to respond to adrenaline, antihistamines or corticosteroids. Those drugs therefore do not provide appropriate procedural prophylaxis. Oestrogen-containing contraception can precipitate or exacerbate attacks and should be avoided; intrauterine and progestogen-only methods are acceptable. A 52 mg LNG-IUD best meets her priorities because it is highly effective, user-independent and supported by FSRH guidance for heavy menstrual bleeding. Her previous severe attack after cervical instrumentation does not make intrauterine contraception contraindicated, but it makes unplanned routine insertion inappropriate. NHS England states that patients with HAE-C1-INH are eligible for C1-inhibitor prophylaxis before medical procedures. Insertion should therefore be coordinated with her specialist immunology service, with pre-procedure C1-inhibitor and immediate availability of her effective on-demand therapy. A uses ineffective histamine-directed prophylaxis. An implant avoids cervical instrumentation but has unpredictable bleeding effects and is not preferable when a suitable bleeding-reducing method can be inserted safely. A copper IUD may worsen her existing heavy bleeding, and progestogen avoidance is unnecessary. The vaginal ring contains oestrogen and may exacerbate HAE despite avoiding instrumentation.

Reference: Commissioned treatment options for patients with hereditary angioedema secondary to C1 esterase inhibitor deficiency (April 2026) — https://www.england.nhs.uk/wp-content/uploads/2026/04/commissioned-treatment-options-for-patients-with-hereditary-angioedema-secondary-to-c1-esterase-inhibitor-deficiency-algorithm.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 International consensus and practical guidelines on the gynecologic and obstetric management of female patients with hereditary angioedema caused by C1 inhibitor deficiency (2012) — https://pubmed.ncbi.nlm.nih.gov/22197274/