Rh Immunisation

Rh
Immunisation

  

• Prenatal Diagnosis of Fetal RhD
  Status by molecular
  analysis
  of maternal
  Plasma,
  
  YMD Lo, et al 
  (Chinese Univ of Hong Kong, China; John
  Radcliffe Hosp, Oxford, England).
  
  N Engl
  J Med 339: 1734-1738, 1998.
  
  
    
  
  The
  rhesus (Rh) blood group system is involved in the
  hemolytic disease of the newborn. In cases in which
  the mother is RhD negative and the father
  heterozygous, there is a 50% chance that the child
  will be Rh positive.
  Several groups have analysed the possibility
  of determining the fetal RhD status from the fetal
  cells isolated from the maternal circulation. The
  feasibility of the RhD genotyping from fetal DNA
  extracted from maternal plasma samples was
  investigated.
  
     
  
  It
  is possible to run a batch of samples to completion,
  allowing detection of as little DNA as is present in
  1 fetal red cell, in 2 hours. 
  In 39 cases where Rh-negative gravidas bore
  Rh-positive fetuses, detection of the Rh-positive
  DNA segments derived from the fetus was possible in
  all 37 pregnancies past 9 weeks of gestation.
  This is a rapid, highly accurate, sensitive
  method of detecting an Rh-positive fetus in this
  sensitized Rh negative woman, given the heterozygous
  Rh positive father. The
  determination can be made as early as the second
  trimester of pregnancy, and intrapartum RhoGam
  administration to such a woman can then be employed
  rationally.