[Rh, Du phenotype in the pregnant woman]

The Rh, Du blood phenotype occurs rarely in the white population (0.23-0.60%). Its clinical significance is whether it should be considered it as Rh positive or negative. A pregnant woman with blood type Rh, Du (+), who delivered an Rh D (+) baby and was not given Rh immune globulin is presented. The Du antigen is manifested by weak expression of the D gene on the RBC envelope, and therefore Rh Du (+) is considered Rh (D) positive. An exception to this rule is the occurrence of transplacental fetomaternal bleeding in an Rh negative mother carrying an Rh positive fetus, when blood is typed close to the time of hemorrhage. In addition, there are other rare phenotypes, such as the D variant and the Du variant, in which there is alloanti-D present in the serum of Rh (D) positive or Rh Du positive patients, causing mild hemolytic disease of the newborn in rare instances.