Which technology may report an Rh-weak D positive as Rh negative?

The gel system has the capacity to detect certain blood group antigens based on the interaction of red blood cells with specific antibodies within a gel matrix. In cases of weak D expression, the gel system can sometimes fail to detect the weak expression due to the way it reads agglutination reactions. If the Rh antigen is only weakly present, the reaction may not be strong enough to produce sufficient agglutination to yield a positive result, leading the test to report the individual as Rh negative.

The gel system operates under principles that rely heavily on the visibility of agglutination, and in circumstances where the D antigen is weak, this can lead to underreporting. In this context, other testing methods may have different sensitivities and specificities, resulting in various outcomes for weak D phenotypes. For example, solid phase and tube testing can be more effective in detecting weak D, depending on their respective protocols and sensitivity.

Recognizing this nuance in Rh typing practices is crucial, as it informs clinical decisions about blood compatibility and the management of Rh immunization risks.