Prenatal rhesus testing

Abstract

Background Prenatal rhesus testing is currently not well standardized. The clinical guidelines and technologies differ between countries and regions. Aims To facilitate implementation of non-invasive prenatal diagnosis of the foetal Rh type (NIPD of Rh) from cell free foetal DNA in maternal plasma. To propel the implementation of targeted administration of anti-D immunoglobulin only to those women who carry a D-positive foetus. Materials and Methods A review of the English literature was performed. Results For foetal DNA extraction a variety of detailed protocols have been published which allow the prediction of the foetal Rh phenotype with an accuracy of above 99%. There are manual as well as automated systems on the market. Several thousand D-negative women have been tested in clinical trials for the foetal D status with real-time PCR. Primers and probes have been designed to be applicable in multi-ethnic populations despite the complex genetic background of the Rh blood group system. A control for foetal DNA has been published in some papers in order to provide an in-process control for cases where the foetus is D (C, c or E) negative. Discussion The scientific community reached a high level of accuracy which allows NIPD of Rh on a large scale. Conclusion NIPD of Rh is now available for all alloimmunized women. In most countries health politicians need to change guidelines now before targeted administration of anti-D immunoglobulin can be offered by obstetricians.

Integration of noninvasive prenatal prediction of fetal blood group into clinical prenatal care

“…The most clinically relevant antibodies, other than anti‐D, are anti‐K (KEL1) and anti‐c, which cause severe HDFN, whereas antibodies to RhE and RhC only occasionally lead to severe clinical manifestations . It is common to find antibodies against more than one blood group antigen, frequently as a combination of anti‐D with an additional antibody . Therefore, combined detection of the most important antigens may be desirable.…”