Policies and procedures related to weak D phenotype testing and Rh immune globulin administration - Results from supplementary questions to the Comprehensive Transfusion Medicine Survey of the College of American Pathologists

Objective.-To determine and evaluate policies and procedures related to wea k D phenotype testing and terminology and the administration of Rh immune g lobulin in selected clinical situations. Design, Setting, and Participants.-Institutions participating in the Colleg e of American Pathologists 1999 J-A Comprehensive Transfusion Medicine Surv ey program were asked to respond to a series of supplementary questions rel ated to weak D phenotype testing and Rh immune globulin administration. Mor e than 3500 institutions and transfusion services participated. Results.-Most supplementary questions elicited more than 3000 responses. De spite no clinical or regulatory mandate, 58.2% of transfusion services rout inely perform an antiglobulin test for the weak D phenotype in patients who test negative with anti-D reagents. Significant differences were found con cerning the transfusion of blood components to patients with the weak D phe notype and the administration of Rh immune globulin to these individuals. A t least one patient with the weak D phenotype with anti-D alloantibody form ation was observed during a 12-month period by 31.8% of transfusion service s. Conclusions.-Significant variability concerning policies and procedures rel ated to weak D typing and terminology was found in this survey. Transfusion of blood components to patients with the weak D phenotype and the administ ration of Rh immune globulin also demonstrated variations. Anti-D alloantib ody formation by patients with the weak D phenotype may not be as rare as p reviously thought. Additional study related to the clinical significance of these results is warranted.