Management of Pregnancies Alloimmunized with Non-Rh and Non-K Alloantibodies

Severe hemolytic disease of the fetus and newborn (HDFN) most commonly occurs due to red cell alloantibodies directed against RhD, Rhc and K antigens. 1 Zwingerman R. Jain V. Hannon J. et al. Alloimmune red blood cell antibodies: prevalence and pathogenicity in a Canadian prenatal population. J Obstet Gynaecol Can. 2014; 37: 784-790 Abstract Full Text Full Text PDF Scopus (29) Google Scholar Non-Rh and non-K alloantibodies have also been implicated in HDFN with most cases having no requirement for antenatal intervention. 1 Zwingerman R. Jain V. Hannon J. et al. Alloimmune red blood cell antibodies: prevalence and pathogenicity in a Canadian prenatal population. J Obstet Gynaecol Can. 2014; 37: 784-790 Abstract Full Text Full Text PDF Scopus (29) Google Scholar , 2 Liu S. Ajne G. Wikman A. et al. Management and clinical consequences of red blood cell antibodies in pregnancy: a population-based cohort study. Acta Obstet Gynecol Scand. 2021; 100: 2216-2225 Crossref PubMed Scopus (4) Google Scholar , 3 Koelewijn J.M. Vrijkotte T.G.M. van der Schoot C.E. et al. Effect of screening for red cell antibodies, other than anti-D, to detect hemolytic disease of the fetus and newborn: a population study in the Netherlands. Transfusion. 2008; 48: 941-952 Crossref PubMed Scopus (160) Google Scholar International practice for monitoring these less frequent alloantibodies varies. North American guidelines recommend an approach akin to that used for high-risk anti-D (Table). Whether existing practices for high-risk alloantibodies should be applied to pregnancies with lower risk non-Rh/K alloantibodies is not well established. TableInternational guidelines regarding antenatal management of lower risk alloantibodies Organization Country (year published) Definition of low risk alloantibodies Titration guidance Critical titre guidance Royal College of Obstetricians and Gynecologists (RCOG) United Kingdom (2014) Non D, K or c alloantibodies. First trimester screen with 1 additional follow up at 28 weeks. ≥32 Swedish Society of Obstetrics and Gynecology Sweden (2015) Cw, f, Jka/Jkb, M, S/s, Fyb, G, Lua/Lub, Kpa/Kpb, Yta, Coa/Cob, Ge2,3 Alloantibody titration every 8 weeks. ≥64a American College of Obstetricians and Gynecologists USA (2018) Not defined Similar titration as anti-D monitoring every 2–4 weeks. ≥8-32 aCritical titre of 64 using gel testing instead of standard tube testing. Open table in a new tab aCritical titre of 64 using gel testing instead of standard tube testing.