Case Study #1
Marilyn Telen, MD
Duke University
Case #1:
The Disappearing Antibody
• 55 year old man presents with bleeding
after an injury.
• + history of transfusion, last 5 years ago
• Sample sent from ED for type and
screen, and 2 units O Neg blood
requested for emergency release.
• Patient received 2 U red cells in ED
without performance of a crossmatch.
Case #1
Type and Screen – initial sample
Forward Type
Anti-A
0
Back Type
Anti-B A1 cells
0
Rh
B cells
Anti-D
4+
3+
4+
Antibody Screen
Cells
PEG IAT
Screening cell #1
3+
Screening cell #2
2+
Screening cell #3
2+
What do you do now?
Blood Type:
O Pos
Event: Emergency Transfusion of
Possibly Incompatible Blood
• Alert the patient's physician that the patient has
an unexpected antibody and to immediately
stop transfusion if possible.
• Make clinical staff aware that the patient may
experience a hemolytic transfusion reaction.
• Ask if the patient has any signs and symptoms
of a hemolytic transfusion reaction.
What Testing Is Done Next?
• Serologic crossmatch by Coombs phase testing
(IAT) of any transfused RBC units to identify if
the blood is compatible and if a transfusion
reaction is likely.
• Antibody panel to identify the patient's antibody.
• Antigen phenotyping of patient and all donor
RBC for the antigen corresponding to any
identified antibody.
• Serologic crossmatch by IAT, and antigen typing
of compatible donors, for future transfusions.
Crossmatch Results
Cells
Donor #1
Donor #2
IAT Result
2+
2+
Conclusion: Both donors used were incompatible.
However, all of the patient's blood specimen was
used in the type and screen and this crossmatch.
There is insufficient plasma to do an antibody
panel. Another sample of blood is requested and
received.
Case #1 – Part 2
Cells
DAT
(polyspecific)
CC
Pretransfusion
0
2+
Post-transfusion
2+MFA
What does a mixed field agglutination reaction suggest?
Why is only one DAT (using the post-transfusion sample)
DAT+?
Mixed Field Agglutination
Antibody Panel Post-Transfusion
Case #1 – Part 2
• What may account for the negative
antibody panel?
• Why was a red cell eluate done?
• Does the eluate help identify the antibody
specificity?
• Can you do a valid crossmatch at this
point?
Case #1 – Part 3
• The patient stabilized in the OR and did
not require further transfusions.
• No hemolytic transfusion reaction was
apparent during hospitalization, and the
patient was discharged 5 days later.
Case #1 – Part 3
Repeat Antibody Screen 2 Weeks Later
Case #1 – Part 3 The End
• The patient has an anti-Fya that reacts more
strongly with homozygous cells.
• The patient's DAT is now negative because
all of the transfused donor RBC have likely
been removed from circulation by anti-Fya.
• If the patient's pretransfusion plasma was
available for antibody titration, do you think
the antibody titer would be lower, the same,
or higher than the titer on the two-week posttransfusion specimen?