Once again, policies vary from laboratory to laboratory since the issue is not directly addressed by blood safety standards. For example, AABB and other standards require a version of the following:
- When clinically significant red cell antibodies are detected or the recipient has a history of such antibodies, RBC components shall be prepared for transfusion that lack the corresponding antigen and are serologically crossmatch-compatible, where serologically is taken to be an IAT at 37oC.
- If no clinically significant antibodies were detected in antibody screen tests and the patient has no record of such antibodies, detection of ABO incompatibility is required, which can be accomplished by immediate spin crossmatch or an electronic crossmatch.
The key issues are whether detectable passive anti-D from RhIg or a record of passive anti-D from RhIg should be considered clinically significant for crossmatch purposes.
Because standards do not directly address these issues, TS laboratories are left to interpret what is required to meet the standards. Practices may be further complicated because of the transfusion service's laboratory information system (LIS).