Obstetric and Newborn Weak D-Phenotype RBC Testing and Rh Immune Globulin Management Recommendations: Lessons From a Blinded Specimen-Testing Survey of 81 Transfusion Services.

CONTEXT.­: Modern RHD genotyping can be used to determine when patients with serologic weak D phenotypes have RHD gene variants at risk for anti-D alloimmunization. However, serologic testing, RhD interpretations, and laboratory management of these patients are quite variable. OBJECTIVE.­: To obtain interlaboratory comparisons of serologic testing, RhD interpretations, Rh immune globulin (RhIG) management, fetomaternal hemorrhage testing, and RHD genotyping for weak D-reactive specimens. DESIGN.­: We devised an educational exercise in which 81 transfusion services supporting obstetrics performed tube-method RhD typing on 2 unknown red blood cell challenge specimens identified as (1) maternal and (2) newborn. Both specimens were from the same weak D-reactive donor. The exercise revealed how participants responded to these different clinical situations. RESULTS.­: Of reporting laboratories, 14% (11 of 80) obtained discrepant immediate-spin reactions on the 2 specimens. Nine different reporting terms were used to interpret weak D-reactive maternal RhD types to obstetricians. In laboratories obtaining negative maternal immediate-spin reactions, 28% (16 of 57) performed unwarranted antiglobulin testing, sometimes leading to recommendations against giving RhIG. To screen for excess fetomaternal hemorrhage after a weak D-reactive newborn, 47% (34 of 73) of reporting laboratories would have employed a contraindicated fetal rosette test, risking false-negative results and inadequate RhIG coverage. Sixty percent (44 of 73) of laboratories would obtain RHD genotyping in some or all cases. CONCLUSIONS.­: For obstetric and neonatal patients with serologic weak D phenotypes, we found several critical problems in transfusion service laboratory practices. We provide recommendations for appropriate testing, consistent immunohematologic terminology, and RHD genotype-guided management of Rh immune globulin therapy and RBC transfusions.

Heterogeneity in Approaches for Switching From Universal to Patient ABO Type-Specific Blood Components During Massive Hemorrhage.

CONTEXT.­: ABO mistransfusions are rare and potentially fatal events. Protocols are required by regulatory agencies to minimize this risk to patients, but how these are applied in the context of massive transfusion protocols (MTPs) is not specifically defined. OBJECTIVE.­: To evaluate the approaches used by transfusion services for switching from universally compatible to patient ABO type-specific blood components during massive hemorrhage. DESIGN.­: We added 1 supplemental multiple-choice question to address the study objective to the 2019 College of American Pathologists proficiency test J-survey (J-A 2019). We also reviewed the available literature regarding this topic. RESULTS.­: A total of 881 laboratories responded to the supplemental question. Approximately 80% (704 of 881) reported a policy for ABO-type switching during an MTP. Policies varied considerably between responding laboratories, but most (384 of 704, 55%) required 2 ABO types to match before switching from universal to recipient-specific blood components. Additional safety measures used in a minority of these protocols included reaction strength criteria (103 of 704, 15%), on-call medical director approval (41 0f 704, 5.8%), universal red cell unit number limits (12 of 704, 1.7%), or the presence of a mixed field (3 of 704, 0.4%). CONCLUSIONS.­: This survey reveals that significant heterogeneity exists regarding the available approaches for ABO-type switching during an MTP. Specific expert guidance regarding this issue is very limited, and best practices have not yet been established or rigorously investigated.