A patient with multiple antibodies has not been transfused for 2 years. What would be most helpful?

Phenotyping the patient’s cells for additional alloantibodies is a valuable step in the context of managing patients with multiple antibodies. When a patient presents with a complex antibody profile, determining their blood type along with the specific antigens present on their red blood cells can help identify any additional antibodies they might possess. This information is crucial for ensuring compatibility in future transfusions.

By phenotyping, it is possible to ascertain which specific antigens the patient has, allowing for a more tailored approach to transfusion. This can help to avoid hemolytic reactions and ensure that the patient receives blood units that are compatible, thereby improving patient safety and outcomes.

Other methods, such as the use of directed donors or proteolytic enzymes, might have their own uses but they do not directly address the need for precise identification of the patient's antigenic profile. Additionally, freezing serum for antigen typing might be relevant for future needs but does not directly contribute to immediate management in this context. Thus, phenotyping serves as the most constructive and informative action to take for the effective management of the patient’s transfusion needs.