Week 13 - Case Studies in Transfusion Flashcards
What do Schistocytes Indicate?
Intravascular Haemolysis
What does Elevated LDH and Bilirubin with Decreased Haptoglobin Indicate?
Haemolysis
What do Spherocytes Indicate?
Haemolytic Anaemia
How to Prove if an IgM Antibody is Present in Plasma
Treat plasma with dithiothreitol (DTT)
What usually Accompanies an IgM Antibody?
Positive C3 (complement)
What does a Negative Donath-Landsteiner Test Indicate?
Rules out paroxysmal cold haemoglobinuria (PCH)
Differential Diagnosis for a Positive DAT with an IgG and have been Treated with IVIg
Warm AIHA
Drug-induced haemolytic anaemia
Passive antibody from IVIg
Hypergammaglobulinaemia from IVIg
Reasons why anti-D might be present
Previous RBC transfusion
Pregnancy
Passive anti-D in IVIg
What can IVIg Contain?
Anti-A and anti-B
What does varying reaction grades show on an antibody screen?
Multiple antibodies
In this image, why is there no reaction in cells that show positivity for Jka?
Kidd and Duffy antibodies demonstrate dosage
If the antibody is weak (1+ reactions in this instance), it will only react against cells that have homozygous expression of the corresponding antigen
Using the frequency table, how many units would have to be screened to find a single unit of antigen negative blood? Patient has an anti-e and anti-Jka and potential anti-K and anti-S
Assume all units are group specific (B pos)
Because all units are group specific, can exclude those percentages
(e-) 0.024 x (K-) 0.909 x (Jka-) 0.236 x (S-) 0.48 = 0.0024
0.0024 = 0.247%
To find the amount of units needed to be screened to find antigen negative blood: 1/0.00247 = 404.8
Therefore 405 units need to be screened
Using the frequency table, in a population of 1000, how many could provide group-specific compatible blood to this individual? Patient is O pos and has an anti-K and anti-E
(O) 0.461 x (D+E-) 0.544 x (K-) 0.909 = 0.228
D+E-: 35.3+17.5+1.6 = 54.4%
0.228 = 22.8%
1000 x 0.228 = 228
Therefore 228 people could provide group specific compatible blood
When performing an alloadsorption on somone how has WAIHA, what cells should you use if their phentype is AB Rh(D) pos, C+ E- c- e+; K- k+; Jk(a-b+); Fy(a+b-)
c-, E-, K-, Jk(a-), Fy(b-)
This is done as the patient can produce antibodies to these antigens
If performing an alloadsorption and the patient has this phenotype: C+ E- c- e+; K- k+; Jk(a-b+); Fy(a+b-), and we want to enzyme treat the cells, which antigen(s) become negative?
Duffy antigens (Fya)
We use enzyme treated cells as it increases antibody uptake
Patient with phenotype Ab pos, C+ E- c- e+; K- k+; Jk(a-b+) has a positive antibody screen, which cells can we expect the antibody to NOT be even if it shows positivity on the screen?
anti-D, anti-C, anti-e, anti-k, anti-Jkb
Because the patient is positive for these antigens
Difference between Apheresis and Random Donor Platelets
Apheresis platelets, blood is taken from patient and spun with patient still there, red cells put back into patient
Therefore only platelets in plasma are taken
Apheresis platelets come from a single donor, random platelets come from multiple donors
Patient has been transfused platelets, they have a positive auto control, so DAT is done. DAT is positive, but eluate is negative, why?
ABO antibodies
Patient has ABO discrepancy in reverse group in the A1 cells, antibody screen is negative. Does this help narrow down what is causing this discrepancy?
Yes
Shows it is not a cold reacting antibody, most likely to be an ABO antibody
Patient has ABO discrepancy in reverse group in the A1 cells, antibody screen is negative. Does this help narrow down what is causing this discrepancy?
Yes
Shows it is not a cold reacting antibody, most likely to be an ABO antibody
All panel cells positive, with uniform reaction strength and a negative auto-control
Antibody against high frequency antigen
Most (or all) panel cells positive with 1+ reactions, negative auto-control
High titre, low avidity ‘like’ antibodies
What does this show?
Ch/Rg antibody
Test sample has been neutralised and the reactivity has become negative = CH/Rg antibody
What can positive auto control help to differentiate between?
Autoantibody and an antibody against a high frequency antigen
