quantity vs. quality - lifestream blood bank · modern blood banking and transfusion practices. 5th...

Quantity vs. Quality: Management of Weak and

Partial D Patients

Andrea McGonigle, M.D.Associate Medical Director, Transfusion Medicine

UCLA Health System

Discussion Outline•Understand why this topic is important•Discuss background on D testing•Explain “Weak D” terminology•Differentiate Weak D Genotype and Partial D•Understand How to Mitigate Risk of Anti‐D

•Describe who gets “Weak D” Testing

•Review which products require selection by Rh type

•Understand who needs Rh D negative blood

•Discuss who needs Rh D genotyping

•Which Genotypes need Rh D negative blood

•Evaluate who needs RhIG

3Andrea McGonigle 2019


•Describe who gets “Weak D” Testing•Review which products require selection by Rh type•Understand who needs Rh D negative blood•Discuss who needs Rh D genotyping•Which Genotypes need Rh D negative blood•Evaluate who needs RhIG


1. Sandler SG, Chen L and Flegel WA. Serological weak D phenotypes: A review and guidance for interpreting the RhD blood type using RHD genotype. Br J Haematol 2017 October ; 179(1): 10–19.

2. Gunson HH, Stratton F, Cooper DG, Rawlinson VI. Primary immunization of Rh‐negative volunteers. Br Med J 1970;1: 593‐5.3. Yazer MH, Triulzi DJ. Detection of anti‐D in D– recipients transfused with D+ red blood cells. Transfusion 2007: 2197‐2201.4. Reid ME and Lomas‐Francis C. The Blood Group Antigen Facts Book.1st ed. London, UK: Academic Press; 2004. p 122.

D Antigen and Antibodies Are Particularly Important•D is most immunogenic Rh antigen1

•80% healthy D‐ volunteers exposed to ≥0.5 mL D+ RBC developed anti‐D2

•22% D‐ non‐oncology hospital patients exposed 1‐10 D+ RBCs made anti‐D3

•Alloantibodies against D are clinically significant•Cause severe hemolytic transfusion reactions (HTR)

•Cause severe hemolytic disease of fetus and newborn (HDFN)4


D Antibodies Are Preventable•Require exposure•RhD negative selection blood prevents antibodies

•Easily found if in stock (RhD typing on unit label)

•RhIG administration following exposure to RhD prevents•Prevention of anti‐D prevention of HTR, HDFN due to anti‐D


So What Are Some Barriers to Preventing Anti-D?•RhD negative blood limited

• ~15% of Caucasians (main component of donor pool)

•Must reserve for patients who need most

•Understanding risk of anti‐D based on Rh D typing results

•Need adequate RhD typing methods1


1. Sandler SG, Roseff SD, Domen RE et al. Policies and Procedures Related to Testing for Weak D Phenotypes and administration of Rh Immune Globulin: Results and Recommendations Related to Supplemental Questions in the Comprehensive Transfusion Medicine Survey of the College of American Pathologists. Arch Pathol Lab Med. 2014: 620‐624.

•Polyclonal IgG•Read result after immediate spin (IS)

•Reagent anti‐D + patient RBCs centrifuge and examine for agglutination

•Caused agglutination with majority of D antigen carrying RBCs•But sensitivity differed between reagents

Historical D Testing Reagents

9

Image credit: Harmening DM. Modern Blood Banking and Transfusion Practices. 5th ed. Philadelphia, PA: F.A. Davis Company; 2005.

Andrea McGonigle 2019

1. Sandler SG, Chen L and Flegel WA. Serological weak D phenotypes: A review and guidance for interpreting the RhD blood type using RHD genotype. Br J Haematol. 2017; 179(1): 10–19.

2. Image credit: Harmening DM. Modern Blood Banking and Transfusion Practices. 5th ed. Philadelphia, PA: F.A. Davis Company; 2005.

•1946 report – blood donor RBCs agglutinated variably1

•Agglutinated with 20 anti‐D sera

•NO visible agglutination with 12 other anti‐D sera

•1958 Standards require “Weak D Test” to confirm D‐negative in donors

False Negatives with Historical Anti-D Reagents


“Weak D Test”•If no visible agglutination with anti‐D at IS:

•Incubate for 30 min., then wash to remove unbound anti‐D

•Next add IgG anti‐human globulin (AHG) to RBCs

•Incubate, centrifuge and observe for agglutination


Image adapted from: Zarandona JM and Yazer MH. The role of the Coombs test in the evaluation of hemolysis in adults. Canadian Medical Association Journal 2006;174:305‐307

Modern Anti-D Testing•Overall more sensitive than historic reagents•Most modern anti‐D reagents are ‘blended’ mixture

•Contain both IgG and IgM•Monoclonal IgM (specific for a single D epitope)

•Monoclonal or polyclonal IgG

•Often different anti‐D clones/potentiating agents present• Impacts sensitivity from different commercial sources1

12

1.Haspel R, Westhoff CM. How do I manage Rh typing in obstetric patients? Transfusion 2015:470‐74.2..Image credit: Harmening DM. Modern Blood Banking and Transfusion Practices. 5th ed. Philadelphia, PA: F.A. Davis Company; 2005.


False Negatives with Modern Anti-D Testing•RBCs with normal levels of D agglutinated by IgM in test1

•May be no or weak agglutination with•RBCs with depressed D antigen levels

•RBCs lacking some D epitopes

•“Weak D” test still used for clarification

13

1.Haspel R, Westhoff CM. How do I manage Rh typing in obstetric patients? Transfusion 2015:470‐74.2..Image credit: Harmening DM. Modern Blood Banking and Transfusion Practices. 5th ed. Philadelphia, PA: F.A. Davis Company; 2005.


•Used inconsistently but generally applied if:•Variable agglutination for D antigen depending on sera used

•“Weak D” testing required for visible agglutination with anti‐D

•Previously called “Du” terminology, phased out after 1992•Modern, more sensitive tests showed many Du were D+

•Term “Weak D” for all weak expressions of D antigen suggested in 19921

Historic Use of Term “Weak D”

15

1. Sandler SG, Chen L, Flegel WA. Serological weak D phenotypes: A review and guidance for interpreting the RhD blood type using the RHD genotype Br J Haematol. 2017 October ; 179(1): 10–19. doi


•For all serologically weak expressions of D antigen• Defined as “Weaker than expected” agglutination with anti‐D

•Most consider ≤2+ “weaker than expected”

•Modern term distinguishes serologic from molecular results•Often incorrectly1 referred to simply as “weak D”

Modern Term: “Serologic Weak D Phenotype”

16

1. Sandler SG, Flegel WA, Westhoff CM, Denomme GA, Delaney M, Keller MA, Johnson ST, Katz L, Queenan JT, Vassallo RR, Simon CD. It’s time to phase in RHD genotyping for patients with a serologic weak D phenotype. Transfusion. 2015; 55:680–689.

2. Image credit: Harmening DM. Modern Blood Banking and Transfusion Practices. 5th ed. Philadelphia, PA: F.A. Davis Company; 2005.

Rh D positive sample demonstrates strong agglutination with anti‐D

Serologic Weak D Phenotype demonstrates “weaker than expected” agglutination with anti‐D


1. Sandler SG, Roseff SD, Domen RE et al. Policies and Procedures Related to Testing for Weak D Phenotypes and administration of Rh Immune Globulin: Results and Recommendations Related to Supplemental Questions in the Comprehensive Transfusion Medicine Survey of the College of American Pathologists. Arch Pathol Lab Med. 2014: 620‐624.2. Image adapted from Harmening DM. Modern Blood Banking and Transfusion Practices. 5th ed. Philadelphia, PA: F.A. Davis Company; 2005.

Serologic Weak D Phenotype•Frequency estimate: 0.2‐1% in U.S.1

•“Weak D” testing still performed to clarify initial results•Term for test used by Standards is still “Weak D test”


Serologic Weak D Phenotype•Includes:

•Weak D genotypes

•Partial D

•”Serologic weak D phenotype” if serologic testing is:•Weak

•Negative with positive weak D test

18

1.Haspel R, Westhoff CM. How do I manage Rh typing in obstetric patients? Transfusion 2015:470‐74.2. Sandler GS. A Guide to Terminology for Rh Immunoprophylaxis. Obstet Gynecol 2017;130:633–5)


} • Routine serology cannot differentiate1• Only molecular analysis can differentiate1,2

Weak D Genotype•Decreased quantity of D antigen

•Do not appear to lack D epitopes

•Majority caused by point mutations in Rh•Mutations lead to D antigen that cannot insert/be retained in RBC membrane like normal1

•1% of Caucasians2

20

1. Denomme GA and Westhoff CM. The Rh System. Technical Manual. 18th ed. Bethesda, MD: AABB; 2014. p3272. Wagner FF and Flegel WA. Rhesus Base. http://www.rhesusbase.info/. <accessed March 10, 2017>


Weak D Genotype•>150 different named types1

•Weak D Genotypes 1‐3•Account for most Serologic Weak D phenotypes of European ancestry

•NOT at risk for clinically significant anti‐D

•Most samples sent for RhD genotyping are Weak D Genotypes 1‐32

•Thus, most Serologic Weak D Phenotypes not at risk for anti‐D

•Some weak D genotypes are at risk for clinically significant anti‐D


1. Wagner FF and Flegel WA. Rhesus Base. http://www.rhesusbase.info/. <accessed March 10, 2017>2.Haspel R, Westhoff CM. How do I manage Rh typing in obstetric patients? Transfusion 2015:470‐74.3. Denomme GA and Westhoff CM. The Rh System. Technical Manual. 18th ed. Bethesda, MD: AABB; 2014. p327.

Partial D•Most commonly picked up as anti‐D in Rh D positive patient

•Majority strongly positive in RhD typing

•But can be Serologic Weak D Phenotype

22

1 Sandler SG, Roseff S, Domen RE, et al. Policies and procedures related to testing for weak D phenotypes and administration ofRh Immune globulin: results and recommendations related to supplemental questions in the Comprehensive Transfusion Medicine survey of the College of American Pathologists. Arch Pathol Lab Med 2014;138:620‐5.


Partial D•Altered or missing D epitopes

•At risk for formation of anti‐D

•0.5‐4% of patients1

•0.5% of Caucasians

•Up to 4% of African American and Hispanics

23

1 Sandler SG, Roseff S, Domen RE, et al. Policies and procedures related to testing for weak D phenotypes and administration ofRh Immune globulin: results and recommendations related to supplemental questions in the Comprehensive Transfusion Medicine survey of the College of American Pathologists. Arch Pathol Lab Med 2014;138:620‐5.


Side By Side Comparison: Weak D Genotype vs. Partial D•Serologic testing may be same “serologic weak D phenotype”

•Only Rh genotyping (molecular testing) can differentiate

•Weak D Genotype•Decreased quantity of D antigen

•Appear to have all D epitopes

•Most are NOT at risk for anti‐D

•Partial D•Altered or missing D epitopes

•ARE at risk for formation of anti‐D

24

1.Table: Haspel R, Westhoff CM. How do I manage Rh typing in obstetric patients? Transfusion 2015:470‐74.


How do we mitigate risk of anti-D formation?•Serologic “Weak D” Testing

•Employed to prevent or detect exposure to D antigen

•Rh D Genotyping to identify patients at risk for anti‐D•Select Rh D negative blood for those in need•Provide RhIG for those in need


Who Gets “Weak D” Testing?•Required to perform testing for:

•Blood donors

•Infants born to Rh D negative mothers

•NOT required for all transfusion recipients1

•Large variation in testing practice

•Helpful in women of childbearing age with D typing discrepancy

28

Standards for Blood Banks and Transfusion Services. 30th Ed. Bethesda, MD: AABB; 2016. p. 36.


Donors: Consequence of False Negative D Typing•False negative unit labeled Rh D negative but D epitopes present•Patient exposed to D potential anti‐D formation

29

No agglutination with anti‐D at initial testing

If no weak D testing


Donors Who Require “Weak D” Testing•Required for all donors with negative Rh D test

30

No agglutination with anti‐D at initial testing

Perform weak D testing


Infants: Consequence of False Negative D Typing•Infants born to Rh D negative mothers

•False negative report infant as Rh D negative

•Leads to incorrect presumption that mom is not candidate for RhIG

•Presence of D epitopes in neonate blood maternal exposure potential anti‐D


‐Or‐

Which Infants get “Weak D” Testing•Infants born to Rh D negative mothers•With negative or weak Rh D test

•Think of fetus as blood “donor” to mom

•Also consider neonate as potential future patient


Who Else Gets “Weak D” Testing?•Optional when typing a patient•Helpful for females <50 y.o. with D typing discrepancies, e.g.:

•Typed as Rh D positive at one institution but negative by your testing(or vice versa)

•By report, patient Rh D positive but negative by your testing (or vice versa)


1. Nester T, Jain N, Poisson J. Hemotherapy Decisions and Their Outcomes. Chapter in The Technical Manual.18th Ed: 5152. Carr R, Hutton JL, Jenkins JA, et al. Transfusion of ABO‐mismatched platelets leads to early platelet refractoriness. Br J Haematol 1990;75: 408‐13.3. Pandey S and Vyas GN. Adverse effects of plasma transfusion. Transfusion 2012;52:65S‐79S.

Selecting Rh D Negative Blood for Those in Need•Selection considered for blood products containing RBCs (RBCs & PLTs)

•Recall PLT components contain trace RBCs1,2

•Not considered for acellular products (plasma & cryoprecipitate)3

•“Rh Negative”•Appears on label of cellular & acellular products

•Conforms to clinical terminology

•May lead to questions



• Describe who gets “Weak D” Testing

• Review which products require selection by Rh type•Understand who needs Rh D negative blood•Discuss who needs Rh D genotyping•Which Genotypes need Rh D negative blood

• Evaluate who needs RhIG


Who needs Rh D negative blood?•Any patient who already formed anti‐D alloantibody

•Prevents HTR

•Male or female

•Intrauterine Transfusion•Females <50 y.o. whom are at risk of forming anti‐D

•Rh D negative

•Certain Weak D genotypes

•All Partial D


Who needs Rh D Genotyping?•Prudent in females <50 y.o. with:

•Unclear risk for anti‐D•D typing discrepancies

•Serologic weak D Phenotype


Which Genotypes Need Rh D negative Blood?

41

1. Haspel R, Westhoff CM. How do I manage Rh typing in obstetric patients? Transfusion 2015:470‐74.2. Flegel WA. How I manage donors and patients with a weak D phenotype. Curr Opin Hematol: 476‐483.

Partial D


• Weak D Genotypes other than 1, 2, 3, 4.0*, 4.1* (*or as specified in report)• All partial D



• Review which products require selection by Rh type•Understand who needs Rh D negative blood•Discuss who needs Rh D genotyping•Which Genotypes need Rh D negative blood•Evaluate who needs RhIG


Who Is a Candidate for RhIG?•Patients that have NOT formed anti‐D alloantibody•Prioritize females <50 y.o. •Patients at risk of forming anti‐D

•Rh D negative

•Weak D genotypes other than 1, 2, 3, 4.0*, 4.1* (*or as specified in report)

•All Partial D

•And exposed to D antigen•Transfusion of Rh D+ blood (RBCs, PLTs)

•Pregnancy with Rh D+ or Serologic Weak D Phenotype infant


What if Rh D Genotyping Is Unavailable?•No genotyping performed or treatment required prior to results•If female <50 y.o. with Serologic Weak D Phenotype

•Treat conservatively as Rh D negative

•Results in some receiving Rh D negative blood unnecessarily

•Avoids missing patients at risk for anti‐D that cannot be distinguished without genotyping


Summary: RhIG Candidacy in PregnancyMother’s test result RhIG Administration

Rh D positive Not Indicated

Rh D negative; no anti‐D alloantibody RhIG administration at:‐ 28 weeks‐ Delivery, if infant with Rh D antigen‐ After event causing fetomaternal hemorrhage

> abortion, ectopic pregnancy, abdominal trauma

Rh D negative; formed anti‐D alloantibody Not indicated

“Serologic Weak D Phenotype”; no anti‐D alloantibody ‐ RhIG administration as with Rh D negative mom‐ OR perform genotyping to determine need

“Serologic Weak D Phenotype”; formed anti‐D alloantibody Not indicated (regardless of genotype)


Summary: Patients Who Need RhIG After TransfusionTest Result Exposure

TypeRhIG Administration

Rh D positive N/A Not Indicated

Rh D negative; no anti‐D alloantibody Rh D+ Platelet ‐ RhoGam: 1 dose

Rh D+ RBCs ‐ WinRho IV: 18 mcg/1 mL Rh D+ RBCs‐ Administer 600 mcg Q8 hours until total dose

administered‐ mL RBC = Transfused mL * estimated packed‐RBC Hct

Rh D negative; formed anti‐D alloantibody N/A Not indicated

“Serologic Weak D Phenotype”; no anti‐D alloantibody As above ‐ RhIG administration as with Rh D negative‐ OR per genotyping to determine need

“Serologic Weak D Phenotype”; formed anti‐D alloantibody N/A Not indicated (regardless of genotype)


quantity vs. quality - lifestream blood bank · modern blood banking and transfusion practices. 5th...

Documents