Anti-D Prophylaxis Reviewed in the Erea of Foetal RHD Genotyping

Minon Jm Gerard Ch,Chantraine F Nisolle M

doi:10.4172/2155-9864.1000302

Abstract

A few years ago, the prevention of anti-D immunization was currently based on systematic postnatal prophylaxis associated with targeted antenatal injection in high-risk situations of foeto-maternal haemorrhage. The failures of prevention are mainly due to the non-respect of established guidelines for RhIG prophylaxis, and to spontaneous undetected foetal-maternal haemorrhages without any obvious cause during the third trimester of pregnancy. In order to reduce the rate of residual post-pregnancy anti-D immunization, several countries decided to associate the classical prophylaxis to a routine antenatal anti-D prophylaxis (RAADP) during the 28th or 29th week of gestation. Since about ten years, the foetal RHD genotyping in maternal plasma enables us to limit the antenatal prophylaxis only to those D- women carrying a D+ foetus. This paper deals with: the advantages of an antenatal prevention in the light of non invasive foetal RHD genotyping, the rules rendering prevention protocols efficient whatever the algorithm applied, and the recommended immuno-haematology follow-up of women who have received RhIG.

Highlights

The pathogenesis of haemolytic disease of the foetus and newborn (HDFN) was first elucidated by Levine (1941) thanks to the discovery of the Rh (Rhesus) blood group by Landsteiner and Wiener in 1940 [1,2]
In order to reduce the rate of residual post-pregnancy anti-D immunization, several countries decided to associate the classical prophylaxis to a routine antenatal anti-D prophylaxis (RAADP) during the 28th or 29th week of gestation
Pregnant women with suspected partial D or Weak D and molecular foetal RHD typing: Because some weak D expression reflects the presence of a partial D and because some carriers of rare weak D types may become immunized, the guidelines for prenatal and perinatal immunohaematology say that the weak D test by indirect antiglobulin technique (IAT) should not be used to D type maternal samples [25]

Summary

Introduction

The pathogenesis of haemolytic disease of the foetus and newborn (HDFN) was first elucidated by Levine (1941) thanks to the discovery of the Rh (Rhesus) blood group by Landsteiner and Wiener in 1940 [1,2] He demonstrated the possibility of maternal immunization through placenta against foetal antigen(s) inherited from the father and lacking in the mother; in this particular case, the D antigen. When appropriate doses of anti-D immunoglobulin’s are injected within 72 hours after delivery, the rate of immunisation is reduced by 90% and the residual risk is around 1 to 2% [5]. A dose-dependant correlation is known to exist between the volume of foeto-maternal haemorrhage and the occurrence of allo-immunisation This is the reason why an adequate and timely administration of anti-D immunoprophylaxis remains essential. These practical aspects, including guidance regarding to routine antenatal anti-D prophylaxis (RAADP), are reviewed in this paper

Systematic Antenatal Prophylaxis

Rh Blood Group System

Rules of Good Practice

Assess FMH Inject appropriate dose

Findings

Conclusion