Connie Westhoff thinks it’s time to implement Rh genotyping for patients with “serologic weak D” results, and she’s here to tell you why!

Dr. Connie Westhoff

Dr. Connie Westhoff

Dr. Connie Westhoff from the New York Blood Center joins Dr. Chaffin to discuss Rh genotyping in pregnant ladies and potential transfusion recipients with unexpected results on serologic D typing. Most laboratorians are aware that testing a patient for the D antigen can be challenging, especially when the results differ from previous results or if the reactions are “weaker than expected.” Dr. Westhoff helps us navigate this challenging area with an awesome summary of the basics of RhD testing, why and how the results can vary, a description of weak D and partial D, and finally, a potential management strategy for donors with unexpected results. If D testing has confused you, or if you don’t “get” weak or partial D, this is the episode for you!

About My Guest:

Connie Westhoff, SBB, PhD is the Executive Scientific Director of the Laboratory for Immunohematology and Genomics at the New York Blood Center and the National Center of Blood Group Genomics in Kansas City. Dr. Westhoff lectures nationally and internationally, and has published more than 100 scientific papers and numerous book chapters. She is an Associate Editor for the Immunohematology and Genomics Section of the AABB journal “Transfusion,” and is also an editor of several editions of the AABB “Technical Manual” (my recommended textbook for those learning Transfusion Medicine). Connie is also an avid supporter of the National Blood Foundation and one of the original inductees to the National Blood Foundation Hall of Fame.

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DISCLAIMER: The opinions expressed on this episode are those of my guest and I alone, and do not reflect those of the organizations with which either of us is affiliated. Neither Dr. Westhoff nor I have any relevant financial disclosures.

The images below are generously provided by Dr. Westhoff.

Slide 1 - RhD structure
Slide 2 - RhD problems
Slide 3 - Weak and partial D
Slide 4 - RhD algorithm
Slide 5 - Benefit of RHD genotyping pregnant women
Slide 6 - Benefit of RHD genotyping recipients
Slide 7 - Summary

Time-Stamped Summary:

  • 1:52: Intro to Dr. Westhoff
  • 3:38: Dr. Westhoff’s background
  • 5:55: Basic testing for RhD
  • 9:38: “D” vs. “RhD” vs. “RHD”
  • 10:46: Why is D testing different from that for K or Jka?
  • 13:28: What’s an epitope?
  • 16:42: “Weak D” vs. “Partial D”
  • 24:56: How practice differs between hospitals with D testing
  • 28:00: Practice recommendation for pregnant females with weak D
  • 32:57: Practice recommendation for weak D transfusion recipients
  • 37:01: Proportion of serologic weak D that are types 1, 2, or 3
  • 39:37: Cost and turnaround time

Further Reading

  • Sandler SG et al. It’s time to phase in RHD genotyping for patients with a serologic weak D phenotype. Transfusion 2015;55:680–689.
  • Kacker S et al. Financial implications of RHD genotyping of pregnant women with a serologic weak D phenotype. Transfusion 2015;55;2095–2103.

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