Transfusion Medicine LECT Flashcards
what fatal disorder does giving Rhogam prevent?
hemolytic disease of the newborn
what are spur cells?
acanthocytes (abnormal RBC’s) seen in chronic compensated hemolytic anemia
what is the McLeod phenotype?
X-linked anomaly of the Kell blood group system in which Kell antigens are poorly detected by laboratory tests
when would you see chronic compensated hemolytic anemia or chronic granulomatous disease?
McLeod phenotype (Kell system)
lack Kx Ag on membrane of neutrophil and monocytes
- deficiency of NADH-oxidase -> no H2O2 to destroy microbes
chronic granulomatous disease (CGD)
what is the Fy(a-,b-) phenotype of the Duffy system resistant to?
plasmodium vivax
what must blood specimen be labeled with at the patients bedside?
time, date, initial of phlebotomist
- gives a permanent and unique ID of each pt
what is a type and screen?
only ABO, Rh and Ab screen performed (no crossmatch)
what is a crossmatch?
actual testing of pts serum compatibility with donor cells
what is an indirect Coombs test?
aka indirect antiglobulin test (IAT)
- detects antibodies in pts SERUM against foreign RBC’s
- Ab must NOT be bound to RBCs (either pts own or transfused) to enable detection
helps to prevent problems (before a transfusion and prenatal testing)
what is a direct Coombs test? (DAT)
detects antibodies (or complement proteins) that attached to pts RBCs.
- helps to diagnose things already going on in your blood
- detects autoimmune hemolytic anemia -> **transfusion rxn workup*
what is an antigen detection test?
commercial anti-sera mixed with patient cells
- confirmation pt +/- Ag on own cells
- usually done in conjunction with Ag typing/screening donor cells for compatibility
what does initial combination of patient sera at room temp with “commercial” suspension of RBCs detect?
“cold” antibodies, IgM
- not usually clinically significant
what is detected at 37 degrees?
“warm” Abs, IgM-IgG mixture and IgG
what are the warm antibodies?
Rh, Kell, Kidd, Duffy systems
detection of warm Abs, IgG coats the RBC membrane
AHG
Ab directed against individuals own RBC Ag
autoantibody
- can cause RBC destruction when pts RBC coated with Ab and serum contains Ab reactive to most donor cells
- difficult to interpret ABO, Rh, AbID and compatibility tests
what type of anemia:
- increase in reticulocytes, increased unconj. bilirubin, decrease haptoglobin
autoimmune hemolytic anemia (AIHA)
- if INTRAvascular hemolysis: hemoglobinemia and -uria
what do you confirm (AIHA)?
confirm with DAT and characterization of autoAb as cold or warm reactive
what is the most common autoAb?
benign cold agglutinin (4C)
- low titer, occ agglutinate cells at room temp, IgM can activate complement in vitro
what can happen if self RBC is heavily coated with Ab?
it can spontaneously agglutinate (false positive)
what can you do to prevent cold Ab from obscuring alloAbs?
prewarm the serum
what is the most common autoAb?
autoAb-I most common, also found on most donor units
- prewarm or autoabsorp serum
what type of anemia shows 70% warm rx, 16% cold?
AIHA
- idiopathic, SLE-associated, or drug induced
- positive DAT is characteristic (IgG, IgG+complement, or complement coated cells)
intravascular hemolysis that may be associated with m. pneumoniae or infectious mononucleosis
- hemolysis increases as pt exposed to cold and complement gets activated
cold agglutinin disease
- avoid cold weather!
- recipient ABO Rh type: forward and reverse typing + weak D
- RBC screening cells for unexpected antibodies in recipient serum, followed to Ab ID if necessary
- mix recipient serum with donor RBCs to detect agglutination
- if no agglutination or hemolysis -> compatible!!
crossmatch/compatibility testing
when would you see fever as an adverse effect of transfusion?
- febrile transfusion rxn
- acute or delayed hemolytic transfusion rxn
- septic shock/rxn
what does transfusion related acute lung injury (TRALI) resemble?
ARDS
- is d/t donor leukocyte Abs
what are the immediate steps that Martin wants us to know in the management of acute transfusion rxns?
- STOP transfusion***
- keep IV open with 0.9% NaCl (normal saline)***
- verify correct unit was given
- notify attending and blood bank
what types of transfusion reactions are due to RBC incompatibility?
- actue hemolytic
- delayed hemolytic
what causes febrile NON-hemolytic rxn?
Ab to donor leukocyte Ag
what causes allergic transfusion rxns?
Ab to plasma protein
what causes anaphylactic transfusion rxns?
Ab to IgA**
what is the appropriate lab response to transfusion rxns?
- check for identification errors***
- visual check of unit and post-transfusion sample for hemolysis
- serologic test or incompatibility
- send donor unit for gram stain and culture***
- F/U H/H and urine for hemolysis***
- MUST RULE OUT TRALI***