RESUMEN
Background: The Rh blood group system is one of the most polymorphic systems in human. Following the discovery of the ABO blood group systems, the greatest breakthrough in transfusion medicine was the discovery of the Rh antigen. . The most common and immunogenic are D, C, E, c and e. The RhD blood group antigen has been shown to be subject to many phenotypic variations. The “weak D” actually refers to red cells with the aberrant Rh-D protein expressing reduced membrane surface D antigen. There is one misconception that individuals with weak phenotypes cannot make anti-D in contrast to partial D because they have low levels of complete D antigen. Methods: Commercially available monoclonal anti D sera was used to detect Rh-D factor status. Individuals found negative with saline anti-D were further investigated and confirmed for weak D antigen by using anti human globulin serum (Indirect Coomb’s technique). Results: During this study 19,347 healthy blood donors were tested for Rh-D factor status. Among these 17,295(89.4%) were Rh-D factor positive while 2052(10.6%) donors were Rh-D factor negative. Among the Rh-D factor negative individuals, 4(0.19%) were weak D positive. Conclusion: It is important to detect and determine all RH negative individuals by saline method for the detection of weak D status to reduce the chances of alloimmunization.