1. Antibody Titer Case Studies
CLS 422
Clinical Immunohematology I
Antibody Titer Case Studies
Please work through these 2 case studies. Ask your site instructor for additional help if necessary.

2. Case One
A twenty-eight year old woman, Gravida 2 para 1, is seen by her nurse midwife for a routine prenatal visit.
The clinician orders a Type and Screen.
The Transfusion Service performs the screen. The screen is positive with anti-E being identified.
The Transfusion Service performs an anti-E titer, with the following results:
Gravida = Number of times pregnant
Para = number of births

3. Case One – Initial Titer
Tube 1 2 3 4 5 6 7 8 9 10 11 12
Reaction Strength
Score

4. Case One – Initial Titer
What is the titer of this sample? 16
What is the score? 43

5. Case One – Initial Titer
Is this infant at risk of HDFN?
Yes, anti-E can cause HDFN.
What test might the clinician order next?
E antigen typing on the father of the baby.
How would that information be useful?
If the father types E negative, the fetus could not have inherited the gene for E, and would also be E negative. Therefore, the maternal anti-E would not destroy the fetal RBCs.

6. Case One The father of the baby was typed for E with positive results.
The mother had a repeat titer drawn at her next prenatal visit, one month later.
The Transfusion Service performed a titer on the current sample with the following results:

7. Case One – Titer Two 1 2 3 4 5 6 7 8 9 10 11 12 Tube Reaction Strength
Score

8. Case One – Titer Two What is the titer of this specimen?32
What is the score? 50

9. Case One – Titer Two
What additional testing must be done to determine the significance of this titer?
Repeat the titer on the initial specimen, and compare results.
The initial sample was titered in parallel, with the following results:

10. Case One – Parallel Titer
Tube 1 2 3 4 5 6 7 8 9 10 11 12
Reaction Strength
Score

11. Case One – Parallel Titer
What it the titer of this specimen? 16
What is the score? 43
Has there been a significant change in the titer?
NO. There is not a difference of 2 tubes, or a change in score of 10 or more.

12. Case One
The mother returned for a prenatal visit in 1 month, and had a titer drawn at that time.
The Transfusion Service performed titers on the current specimen, and ran the initial specimen in parallel, with the following results:

13. Case One – Titer Three
Tube 1 2 3 4 5 6 7 8 9 10 11 12
Reaction Strength
Score
Initial Titer run in parallel
Tube 1 2 3 4 5 6 7 8 9 10 11 12
Reaction Strength
Score

14. Case One – Titer Three What is the titer and score of the third titer?
>E titer is 64, with a score of 69.
Has there been a significant change from the original specimen?
Yes, the parallel titer is still 16, with a score of 43. The new titer has increased by 2 tubes, and the score has changed by more than 10.
How might the clinician follow the pregnancy from now on (other than additional titers)?

15. Case One Ultrasound Amniocentesis PUBS (cordiocentesis)
Peak systolic velocity of the middle cerebral artery (MCA PSV)
Amniocentesis
Bilirubin levels
Fetal lung maturity
PUBS (cordiocentesis)

16. Case Two
A 42 year old woman was seen by her obstetrician at 26 weeks of gestation during a high risk pregnancy.
An antenatal Rh Immune Globulin evaluation was drawn at that time.
The laboratory performing the RhIG evaluation got a positive antibody screen, with anti-D being identified.

17. Case Two The physician requested an anti-D titer be performed.
The results were as follows:
Tube 1 2 3 4 5 6 7 8 9 10 11 12
Reaction Strength
Score

18. Case Two – Titer One What is the titer and score?
Anti-D titer is 2, score 10.
What question might the technologist ask at this point?
Has the patient already received Rh Immune Globulin during this pregnancy?
Anti-D from RhIG rarely titers greater than 4.

19. Case Two – Titer One
A review of the woman’s chart revealed she had received RhIG following amniocentesis at 18 weeks gestation.
The anti-D detected at 26 weeks was attributed to passive anti-D from RhIG.
The patient received an additional dose of RhIG, and the pregnancy proceeded without complications.

20. How did you do? If you had problems, review the titer presentation.
The End
How did you do?
If you had problems, review the titer presentation.