TraQ Program of the BC PBCO

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Last Updated July 11, 2011

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Contributed by Darlene Mueller, ART, Matsqui - Abbotsford - Sumas (MSA) General Hospital

HISTORY

Mrs. D.M. is a 34 year old female admitted at 37 weeks gestation for induction of a twin pregnancy.

• Pregnancies:
• Transfusions: No prior history
2 prior pregnancies, the last two years earlier. Anti-Jk^a reported during prenatal testing of current pregnancy. Blood type reported as B Rh positive.

A group and screen was ordered but because of the antibody history three units of Jk(a-) concentrated red cells were crossmatched.

TESTS

• Initial crossmatch results

Given these crossmatch results, the technologist notified the attending physician that there were additional antibodies present and compatible blood was not available at this time. She also requested cord bloods as soon as possible.

Mother's Tests

• Antibody Identification
• Phenotyping
• Summary of panel, phenotyping, and exclusion cells
• Crossmatch results (post-antibody investigation)

Twin A and Twin B Tests

Female (twin A) and male (twin B) babies were born without incident later the same day. Cord blood testing results were as follows:

• Twin A-blood grouping and DAT results
• Twin A-panel results (eluate)
• Twin A-phenotyping
• -----------------------------------------------
• Twin B-blood grouping and DAT results
• Twin B-panel results (eluate)
• Twin B-phenotyping

Father's Tests

As a follow-up a blood specimen was taken from the father:

• Father's phenotyping

CASE SUMMARY AND QUIZ

After reviewing the case summary, consider these questions:

1. Outside of the Rh system, which antibody is well documented as a cause of severe hemolytic disease of the newborn (HDN)?

   Answer

2. Phototherapy and exchange transfusion can be used to prevent kernicterus due to hyperbilirubinemia in HDN. Neither therapy was needed in this case. At which level of total serum birubin is exchange transfusion typically considered?

   Answer

3. Which precautions are required when antigen phenotyping CDP-treated red cells?

   Answer

4. What is a "p value" and how can it be used as a tool when identifying antibodies?

   Answer

FURTHER READING

Bowman JM, Pollock JM, Manning FA, Harman CR, Menticoglou S. Maternal Kell blood group alloimmunization. Obstet Gynecol 1992;79(2):239-44. [ Medline ]

Canadian Paediatric Society. Approach to the management of hyperbilirubinemia in term newborn infants. Paed & Child Health 1999;4(2):161-4. (revision in progress March 2002)

Graphpad. Online tool for calculating p values

Judd WJ. Practice guidelines for prenatal and perinatal immunohematology, revisited. Transfusion 2001 Nov; 41(11): 1445-52.

Judd WJ, Davenport R. On the high probability that a perceived lack of value of obtaining a p value will be detrimental to patient care. Transfusion 1997; Aug;37(8):877.

Kanter MH, Poole G, Garratty G. More on p values in antibody identification. Transfusion 1997;37(11-12):1221-2.

Sterne JA, Davey Smith G. Sifting the evidence-what's wrong with significance tests? (Br Med J 2001;322:226-31.