Red cell antibodies

Question 1

You are referred a woman who is G4P1 who is Anti-K (Kell antibody) positive with a titre of 1:128.

Outline your assessment, investigations and management plan for this woman.

Answer 1

History:

• Outcomes of previous pregnancies including need for invasive testing, IUT, neonatal anaemia, jaundice and transfusions.
• Male partner’s Kell phenotype.

Explanation of condition:

• She has antibodies towards a red blood cell antigen called Kell. These antibodies can cross the placenta into baby; if baby is Kell-positive they can develop significant anaemia secondary to antibody destruction of cells that make red blood cells.
• This can result in fetal or neonatal anaemia, hydrops, perinatal death and preterm birth.

Management plan:

• If sure paternity: paternal phenotyping with serology. If K neg - no further action. If K positive homozygous refer to MFM. If K positive heterozygous proceed with cfFDNA testing.
• cfFNDA testing: if K positive refer to MFM. If K negative no further action.
• Referral to tertiary centre/MFM as Anti-K can cause fetal anaemia even at low titres.
• Monthly Anti-K titres until 28 weeks; then titres every 2 weeks until delivery.
• IOL at 37 weeks,
• Neonatal cord blood at delivery: DAT, Hb, bilirubin.