In a prenatal workup, how can an ABO discrepancy due to an antibody directed against typing sera be resolved?

In a prenatal workup, resolving an ABO discrepancy caused by an antibody directed against typing sera can effectively be achieved by washing the patient’s red blood cells (RBCs) and then repeating the testing. This approach helps eliminate any potential interfering substances from the serum that might be masking the true results of the ABO typing.

When patient RBCs are washed, any loosely bound antibodies or serum components are removed. This leaves behind only the patient's own cells in a clean environment, allowing for more accurate readings during the repeat typing process. Additionally, it reduces the chance of false reactions caused by antibodies present in the serum that would otherwise bind to the typing reagents. Thus, when the testing is repeated after washing, it can lead to clearer and more accurate results regarding the ABO group.

Other methods listed, such as using A1 lectin or anti-A,B to extend incubation times, and repeating the reverse group with A2 cells, may not address the underlying issue caused by the presence of interfering antibodies. Therefore, the washing of cells and retesting stands out as the most direct and effective method for resolving the discrepancy in such scenarios.