University of Wisconsin–Madison Medical College of Wisconsin

A Case of Weak D Serologic Phenotype

Alice M. Boshoven, MD; Laura Verhagen, DO

WMJ. 2024;123(1):56-58.

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Introduction: Rh D alloimmunization is the serologic response that occurs when Rh D-negative patients are exposed to Rh D-positive blood. Rh D blood typing is recommended in pregnancy to prevent alloimmunization.

Case Presentation: A 27-year-old gravida 3, para 2012 (G3P2012) previously Rh D-negative female presented with discordant and weakly positive Rh D blood typing results. Confirmatory genetic testing revealed weak D phenotype that can be treated clinically as Rh D-positive.

Discussion: Genetic variants of Rh D can cause varied blood typing results depending on the hospital reporting protocol utilized. If labeled as Rh D-negative, this could lead to unnecessary administration of Rh D immunoglobulin in pregnancy. Genetic variants should be suspected when patients are noted to have blood typing results that are discordant or weakly positive.

Conclusions: Rh D genotyping should be considered when discordant or weakly positive Rh D blood type results are noted in order to confirm and classify genetic subtype.

Author Affiliations: Medical College of Wisconsin, Fox Valley Family Medicine Residency, Appleton, Wisconsin (Boshoven, Verhagen).
Corresponding Author: Alice M. Boshoven, MD, Medical College of Wisconsin, Fox Valley Family Medicine Residency, 229 S Morrison St, Appleton, WI 54911; phone 920.832.2783; email; ORCID ID 0000-0003-1482-9605
Funding/Support: None declared.
Financial Disclosures: None declared.
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