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

Glenn Ramsey, From the Department of Pathology, Northwestern University, Chicago, Illinois (Ramsey).
Yara A. Park, Department of Pathology and Laboratory Medicine, University of North Carolina, Chapel Hill (Park).
Anne F. Eder, Center for Biologics Evaluation and Research, Food and Drug Administration, Silver Spring, Maryland (Eder).
Aleh Bobr, Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota (Bobr).
Matthew S. Karafin, Blood Center of Wisconsin, Milwaukee (Karafin).
Julie K. Karp, Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, Pennsylvania (Karp).
Karen E. King, Department of Pathology, Johns Hopkins University, Baltimore, Maryland (King).
Monica B. Pagano, Department of Laboratory Medicine and Pathology, University of Washington, Seattle (Pagano).
Joseph Schwartz, Department of Pathology and Cell Biology, Columbia University Medical Center, New York, New York (Schwartz).
Zbigniew M. Szczepiorkowski, Department of Pathology and Laboratory Medicine, Dartmouth College, Hanover, New Hampshire (Szczepiorkowski).
Rhona J. Souers, Department of Biostatistics (Souers), College of American Pathologists, Northfield, Illinois.
Lamont Thomas, Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, Pennsylvania (Karp).
Meghan Delaney, The Division of Pathology & Laboratory Medicine, Children's National Hospital, and the Departments of Pathology & Pediatrics, The George Washington University School of Medicine & Health Sciences, Washington, DC (Delaney).

Document Type

Journal Article

Publication Date

1-1-2023

Journal

Archives of pathology & laboratory medicine

Volume

147

Issue

1

DOI

10.5858/arpa.2021-0250-CP

Abstract

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.

Department

Pathology

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