Management of anti-Colton(a) alloimmunisation in pregnancy: a case report.

Dear Sir, Diagnosis and management of anti-Coltona (Coa) alloimmunisation during pregnancy is a rare and challenging condition. Only five cases have been described up to now, four in the 1970s and one in 2008, but diagnosis and management have changed in the meantime (Smith et al., 1970; Simpson, 1973; McIntyre et al., 1976; Fuhrmann et al., 1979; Michalewska et al., 2008). We here present such a case, its management and favourable outcome. Alloimmunisation of a Coa-negative pregnant woman, carrying a Coa-positive foetus, may cause haemolytic disease in the foetus and newborn (HDFN) (Smith et al., 1970; McIntyre et al., 1976; Michalewska et al., 2008). Nowadays, monitoring is performed by laboratory testing of antibody titre, although it is unknown whether antibody titration is helpful (de Haas et al., 2015). Of greater importance are doppler flow measurements of the peak systolic velocity of the middle cerebral artery (MCA-PSV) (Zimmerman et al., 2002;Michalewska et al., 2008; Moise & Argoti, 2012; de Haas et al., 2015). In cases of foetal anaemia, intrauterine blood transfusion (IUT) by cordocentesis is established, challenged by the allocation of compatible blood (de Haas et al., 2015). A 32-year-old woman (blood group 0 RhD−-, RhC−, Rhc+, RhE−, Rhe+, K−, Coa−) was admitted to our hospital at 20+ 3 gestational weeks (gw) with an alloimmunisation against blood group antigen Coa with increasing antibody titer. Antibody identification was performed by indirect antiglobulin testing (IAT) and enzyme (papain) testing using an in-house panel and Coombs and neutral cards (IAT/ID and papain/ID) (BioRad, Cressier, Switzerland) (Table 1). Titration was performed in IAT/ID using a Coa-heterozygous test cell. A Coa-antigen determination of the foetus’ father, using IAT/ID and non-commercial anti-Coa and anti-Cob sera, showed that he was Coa homozygous. Monitoring of the foetus was performed every 1–2 weeks byMCA-PSVmeasurements (Table 2). Between 28 and 32 gw, the MCA-PSV gradually increased with values above the 95th percentile and a Monocyte Monolayer Assay (MMA) showed a value of 29% (Nance et al., 1989), so that anaemia was suspected and foetal transfusion planned. We used Coa-, RhD-, RhC-, RhEand Kell-negative blood from a donor, as women between 0 and 50 years of age should be transfused with Rh/K phenotype compatible blood only,