An anti-Kell sensitised pregnant woman is being counselled about fetal surveillance. How does haemolytic disease caused by anti-Kell differ from that caused by anti-D?
- A It causes severe fetal anaemia largely through suppression of erythropoiesis, with anaemia disproportionate to the degree of haemolysis ✓
- B It produces more intense hyperbilirubinaemia because haemolysis dominates
- C It affects only the placenta and never crosses into fetal circulation
- D Maternal antibody titre correlates reliably with fetal severity, unlike anti-D
Correct answer: A. It causes severe fetal anaemia largely through suppression of erythropoiesis, with anaemia disproportionate to the degree of haemolysis
Explanation
Anti-Kell antibodies destroy fetal erythroid precursors (BFU-E) in addition to coating mature cells, so fetal anaemia develops chiefly through impaired red cell production rather than peripheral haemolysis. Bilirubin rise is therefore modest relative to the degree of anaemia, and maternal titres correlate poorly with fetal severity, mandating early MCA Doppler surveillance. Option B describes the anti-D pattern, option C is anatomically false, and option D reverses the true relationship between titre and severity.
Reference: Williams Obstetrics, 26th ed.
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Written and medically reviewed by the StethoPrep medical team.