Kell isoimmunisation

Question 1

Kell

Answer 1

• Maternal antibody associated with severe HDFN
• 90% of population are Kell negative
• Most immunisations are from blood transfusions
• Kell antibodies cause anaemia by two pathways
  o Bone marrow aplasia due to reaction with erythrocyte precursors
  o Haemolytic anaemia due to reaction with fetal erythrocytes
• Titres are not predictive of fetal anaemia

Question 2

Investigations

Answer 2

o Consider paternal genotype +/- determination of fetal genotype depending on location/ability to attend for surveillance

Question 3

Management

Answer 3

• MCA PSV indicated from 16/40 in any Kell-sensitised pregnancy (ie titre >=1:2)
• Fetal blood sampling and IUT indicated as per Rhesus protocol
• Intrapartum
  o Delivery at 37-38/40 if IUT or high titre
  o Vaginal birth acceptable
  o CEFM during labour
  o Paeds in attendance
• Postpartum
  o Cord blood for FBE, group and screen, Coombes, bilirubin
  o Ongoing surveillance for anaemia (IUT suppresses haemopoesis) and jaundice