Antibody Titer Case Studies

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Antibody Titer Case Studies
CLS 422 Clinical Immunohematology I

• Please work through these 2 case studies. Ask
  your site instructor for additional help if
  necessary.

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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

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Case One Initial Titer
Tube 1 2 3 4 5 6 7 8 9 10 11 12
Reaction Strength 4 3 2 2 1 0 0 0 0 0 0 0
Score 12 10 8 8 5 0 0 0 0 0 0 0
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Case One Initial Titer

• What is the titer of this sample?
• 16
• What is the score?
• 43

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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.

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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

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Case One Titer Two
Tube 1 2 3 4 5 6 7 8 9 10 11 12
Reaction Strength 4 3 3 2 1 1 0 0 0 0 0 0
Score 12 10 10 8 5 5 0 0 0 0 0 0
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Case One Titer Two

• What is the titer of this specimen?
• 32
• What is the score?
• 50

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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

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Case One Parallel Titer
Tube 1 2 3 4 5 6 7 8 9 10 11 12
Reaction Strength 4 3 2 2 1 0 0 0 0 0 0 0
Score 12 10 8 8 5 0 0 0 0 0 0 0
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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.

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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

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Case One Titer Three
Tube 1 2 3 4 5 6 7 8 9 10 11 12
Reaction Strength 4 4 4 3 3 2 1 0 0 0 0 0
Score 12 12 12 10 10 8 5 0 0 0 0 0
Initial Titer run in parallel
Tube 1 2 3 4 5 6 7 8 9 10 11 12
Reaction Strength 4 3 2 2 1 0 0 0 0 0 0 0
Score 12 10 8 8 5 0 0 0 0 0 0 0
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Case One Titer Three

• What is the titer and score of the third titer?
• gtE 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)?

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Case One

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

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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.

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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 1 1 0 0 0 0 0 0 0 0 0 0
Score 5 5 0 0 0 0 0 0 0 0 0 0
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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.

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Case Two Titer One

• A review of the womans 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.

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The End

• How did you do?
• If you had problems, review the titer
  presentation.