Monitoring of prenatal patients using a combined antibody titre for Rh and non‐Rh antibodies

Abstract

This was a laboratory exercise designed to determine whether combined antibody titrations in the presence of multiple antibodies achieve a critical level earlier or at the same time as antibodies having individual antibody titrations. Management of haemolytic disease of the fetus and newborn involves monitoring maternal antibody concentration by antibody titration. Separate titrations are generally performed for each antibody. Thirty-one samples containing combinations of two different Rh and/or non-Rh antibodies were examined with separate titres for each antibody and one single combined titration. Of 31 samples, 19 (61.3%) showed an increased combined titre. Of 12 samples that showed no increase, 10 contained a separate titre of <1 for either one or both antibodies. Where both antibodies had a separate titre of ≥1, 15 of 17 (88.2%) showed an increased combined titre. In contrast to the separate titration method, no decrease in titre level was observed using the combined method. Where two antibodies are present, titrations performed by a combined method will produce titre levels equal to or higher than antibodies titred individually. Therefore, a combined titration can be expected to reach a critical titre level as early as, or earlier in gestation than, antibodies monitored by a single titration method. Further studies relating fetal outcomes to titration methodology would be valuable in determining the validity of this approach for prenatal management. Cost-effectiveness of this approach to prenatal screening should also be assessed.