Pretransfusion and Compatibility Testing
What conditions are required for an Electronic Crossmatch?
-2 blood types are on file for the patient -Antibody screen is NEGative
Platelet Compatibility High Risk Patients (BMT Pts)
-Avoid ABO incompatibility -literature suggests ABO Incompatible PLTs can increase the rate of alloimmunization and platelet refractoriness, and reduce survival after marrrow transplant (Practical Clinical Pathology 2nd Ed: p92)
What causes POSitive results in the crossmatch?
-Incorrect ABO grouping of patient or donor -Alloantibody or Autoantibody in patient reacting with the corresponding antigen on the donor RBCs -Donor having a positive DAT -Abnormalities in patient serum such as increased protein concentration (rouleaux) or contaminants in the system
Fill in the Blank Cold autoantibodies may be benign or pathologic. Anti-I interacts with all _______ cells. Anti-i interacts with _________ cells
adult fetal
What is the most common cause of error in transfusion medicine?
misidentification of the recipient
Name That Blood Group! Type ___ blood gets its name because it has neither A nor B antigens! In other languages ___ is often pronounced as "null". Antigens (on the surface of the red blood cells): ---O indicates there are neither A nor B antigens. ---Rh+ indicates there are Rh antigens. Antibodies (in the blood plasma): ---A antibodies. ---B antibodies (If there are Rh antigens but no A nor B antigens, the antibodies present in the blood plasma are A and B antibodies.)
Blood type O Rh+
Name That Blood Group! Antigens (on the surface of the red blood cells): No antigens! (O indicates there are neither A nor B antigens.) (Rh- indicates there are no Rh antigens.) Antibodies (in the blood plasma): ---A antibodies. ---B antibodies. ---Rh antibodies. (If there are no antigens at all on the surface of the red blood cells, all three possible antibodies are present in the blood plasma: A, B and Rh antibodies.)
Blood type O Rh-
Blood donor and recipient samples used in cross matching must be stored for a minimum of how many days following transfusion? A) 2 B) 5 C) 7 D) 10
C
Compatibility testing: A) proves that the donor's plasma is free of all irregular antibodies B) detects most irregular antibodies on the donor's RBCs that are reactive with patient's serum C) detects most errors in the ABO groupings D) ensures complete safety of the transfusion
C
The process of affixing a label with recipient information to a blood unit is called: A) Labeling B) Scanning C) Tagging D) Crossmatching
C
True or False Most fatal transfusion reactions are caused by clerical errors
True
Which blood product has the highest discard rate? Why?
A platelet product (single-donor platelet) has the highest discard rate because it has the shortest lifespan(~ 9.5days)
What is a "Cross-Match" ?
A test between the Patient's PLASMA and donor's cells
A patient is a subgroup of A (Asub), Rh-POSitive with anti-A1 in their serum. How many units would you have to screen to find 1 unit that is compatible with the patient's anti-A1? A) 5 B) 10 C) 15 D) 20
A) 5 20% of the population is A1 NEGative. To find one unit that is A1 NEGative, 5 units would have to be screened (20/100 = 1/x, 20x = 100, x = 100/20, x = 5 units) [AABB Tech Manual 2017, p 271]
Patient Blood Type A Can receive RBCs from what types?
A, O
Patient Blood Type AB Can receive RBCs from what types?
A, B, AB, O
Patient Blood Type B Can receive PLASMA from who?
B AB
What type(s) of red cells is (are) acceptable to tranfuse to an O-negative patient? A) A negative, B negative, AB negative, or O negative B) O negative C) AB negative D) AB negative, A negative, B negative
B) O negative An O-NEGative individual has both anti-A and anti-B and may receive only O-negative cells
Patient Blood Type B Can receive RBCs from what types?
B, O
What does a minor crossmatch consist of? A) Recipient plasma and recipient red cells B) Recipient plasma and donor cells C) Recipient red cells and donor plasma D) Donor plasma and donor red cells
C) Recipient red cells and donor plasma A minor crossmatch consists of recipient red cells and donor serum or plasma
What is an IAT?
Indirect Antiglobulin Test
Why is it more important for the donor unit to be compatible with the mother than the infant?
Mom's blood in baby's circulation has antibodies
What is an Autocontrol?
Patient cells are mixed with patient plasma. Used to rule out an AUTOantibody. If all 3 screening cells agglutinate, but the auto control is negative, it's a good indicator that you're dealing with an alloantibody rather than autoantibody.
Platelet Compatibility
Platelets carry AB antigens and are potentially targeted by the recipient's isoagglutinins, which may result in a poor rise in PLT count after transfusion (Practical Clinical Pathology 2nd Ed: p92)
Which of the following comprises an abbreviated crossmatch? A) ABO, Rh, and antibody screen B) ABO, Rh, antibody screen, IS crossmatch C) Type and screen D) ABO, Rh, IS crossmatch
B) ABO, Rh, antibody screen, IS crossmatch The abbreviated crossmatch usually consists of a type and screen and an immediate spin crossmatch.
Patient Blood Type A Can receive PLASMA from who?
A AB
Which of the following tests are mandatory to perform on red blood cell units that have just been received from a blood supplier? A) abo typing B) rh(d) typing C) Weak d test D) extended antigen phenotype
A and B
A patient developed an anti-Jk^a antibody 5 years ago. The antibody screen is currently negative. To obtain suitable blood for transfusion, which procedures apply? A) Type the patient for the Jk^a antigen as an added part to the crossmatch procedure B) Crossmatch random donors with the patient's serum C) Type the donor units for the Jk^a antigen, and then crossmatch the Jk^a negative units for the patient D) Computer-crossmatch Jk^a negative donor units
A and C
How could the transfusion of an apheresis platelet unit trigger a hemolytic transfusion reaction in a recipient?
A hemolytic transfusion reaction can occur when a non-blood group O transfusion recipient is transfused with blood type O single-donor platelets that contain a high titer of anti-A or anti-B
What is a Minor Crossmatch?
A minor crossmatch consists of recipient red cells and donor serum or plasma
A patient is a subgroup of A (Asub), Rh-POSitive with anti-A1 in their serum. How many units would you have to screen to find 1 unit that is compatible with the patient's anti-A1? A) 5 B) 10 C) 15 D) 20
A) 5 20% of the population is A1 negative. To find one unit that is A1 negative, 5 units would have to be screened (20/100 = 1/x, 20x = 100, x = 100/20, x = 5 units) [AABB Tech Manual 2017, p271]
In what patient population may we observe the following results? anti-A: 4+ anti-B: 0 anti-D: 4+ A1 cells: 4+ B cells: 1+ A) labor and delivery patient B) 30-year old GI bleed patient C) 2-year old pre-surgical patient D) 16-year old ACL repair surgery patient
C) 2-year old pre-surgical patient ABO antibodies are NOT present at birth. ABO antibodies develop in response to the environment from 3-6 months of age and continue to increase in titer until achieving adult levels at 5-10 years of age. [AABB Tech Manual 2017, p269]
In what population may we observe the following results? Anti-A: 4+ Anti-B: 0 Anti-D: 4+ A1 cells: 0 B cells: 1+ A) labor and delivery patient B) 30-year old GI bleed patient C) 2-year old pre-surgical patient D) 16-year old ACL repair surgery patient
C) 2-year old pre-surgical patient ABO antibodies are not present at birth. ABO antibodies develop in response to the environment from 3-6 months of age and continue to increase in titer until achieving adult levels at 5-10 years of age. [AABB Tech Manual 2017, p269]
If the antigen frequencies for K = 0.09 and Fya = 0.66, what percent of type-specific units would be compatible for a patient with anti-K and anti-Fya? A) 10 B) 42 C) 31 D) 92 E) 100
C) 31 The negative antigen frequencies are used in the formula below to determine the percent of type-specific units that would be compatible for the patient. Negative antigen frequencies are determined by subtracting the percent antigen frequency from 100%. The negative antigen frequency for K in this case is 0.91 (1.00-0.09) and the negative antigen frequency for Fya is 0.34 (1.00-0.66) %compatible units available = 100 X (Neg frequency #1 X Neg frequency #2...) %compatible units available = 100 X (0.91 X 0.34) = 30.94 or 31%
Mixed field agglutination encountered in ABO grouping with no history of transfusion would most likely be due to: A) Bombay phenotype (Oh) B) T activation C) A3 red cells D) positive indirect antiglobulin test
C) A3 red cells Mixed-field reactivity is a characteristic of the A3 subgroup. Transfusion history would be important to be sure it is not 2 cell populations. [AABB Tech Manual 2017, p271]
AHG (Coombs) control cells: A) can be used as a positive control for anti-C3 reagents B) can be used only for the indirect antiglobulin test C) are coated only with IgG antibody D) must be used to confirm all positive antiglobulin reactions
C) are coated only with IgG antibody AHG control cells are IgG-sensitized cells that react with the anti-IgG in the AHG reagent to demonstrate AHG was added and not neutralized by insufficient washing of the tests prior to its addition. [AABB Tech Manual 2017, p 486]
The following test results are noted for a unit of blood labeled group A, Rh-NEGative: Cells tested with: Anti-A: 4+ Anti-B: 0 Anti-D: 3+ What should be done next? A) transfuse as a group A, Rh-NEGative B) transfuse as a group A, Rh-POSitive C) notify the collecting facility D) discard the unit
C) notify the collecting facility A serological test to confirm the ABO on all RBC units and Rh on units labeled as Rh-NEGative must be performed prior to transfusion. Any errors in labeling must be reported to the collection facility. [AABB Tech Manual 2017, p475]
Having checked the patient's prior history and having received the specimen request, you: A) do not have to repeat the ABO and Rh if the name and hospital number agree B) do not have to repeat the indirect antiglobulin test (IAT) if the previous IAT was negative C) have to perform a crossmatch only if one has not been done within the last 2 weeks D) have to compare the results of your ABO, Rh, and IAT with the previous results
D
What type of blood should be given in an emergency transfusion when there is no time to type the recipient's sample? A) O Rh (D)-NEGative, whole blood B) O Rh (D)-POSitive, whole blood C) O Rh (D)-POSitive, packed cells D) O Rh (D)-NEGative, packed cells
D
Which is true regarding compatibility testing the infant younger than 4 months old? A) a DAT is required B) a crossmatch is not needed with the infant's blood when unexpected antibodies are present C) maternal serum cannot be used for antibody detection D) to determine the infant's ABO group, RBCs must be tested with reagent anti-A, anti-B, and anti-A,B
B
What comprises a Type and Screen?
1) ABO group 2) Rh(D) type 3) Antibody screen test (looking for red blood cell antibodies)
Identify the mandatory tests that are part of a pre-transfusion testing work-up.
1) ABO typing 2) Rh typing 3) antibody screen
What routine tests are done on the mother after delivery?
1) ABO/Rh 2) Antibody screen 3) Autocontrol
What are the Age of Specimen requirements?
1) Samples from potential recipients who have been pregnant or transfused within the preceding 3 months must be collected within 3 days of transfusion. If no patient history is available, collect the specimen within 3 days of transfusion. 2) Once the initial testing is complete, additional units may be crossmatched using the original specimen for the next 3 days. (Collection day is day 0)
What does Pre-Transfusion testing do?
1. Verify ABO compatibility 2. Detect most clinically significant antibodies 3. Ensure the recipient is issued designated blood components
What are the preferred choices for transfusion of RBCs into an AB group recipient?
1st choice AB 2nd choice A 3rd Choice B 4th Choice O
Fill in the Blank A Blood Bank specimen must have ________ unique patient identifiers, the date of collection, and initials or signature of the person who collected the sample
2
What procedure utilizes leukapheresis to collect the buffy coat from whole blood? A) Photopheresis B) Plasmapheresis C) Therapeutic apheresis D) Erythrocytapheresis
A) Photopheresis Photopheresis utilizes leukapheresis to collect the buffy coat layer from whole blood. These cells are treated with 8-methoxypsoralen, exposed to ultraviolet A light and then reinfused into the patient. Photopheresis has been shown to be efficacious and has been approved by the Food and Drug Administration for the treatment of cutaneous T-cell lymphoma. Plasmapheresis is the removal and retention of the plasma, with return of all cellular components to the patient. Therapeutic apheresis (TA) involves the removal of a specific blood component, with return of the remaining blood constituents to the patient. However, with TA the component being removed is considered pathological or contributing to the patient's underlying disease state. Erythrocytapheresis, or red cell exchange, removes a large number of red blood cells from the patient and returns the patient's plasma and platelets along with compatible allogeneic donor red blood cells.
Can a crossmatching be performed on October 14th using a patient sample drawn on October 12th? A) Yes, a new sample would not be needed B) Yes, but only if the previous sample has no alloantibodies C) No, a new smaple is needed because the 2-day limit has expired D) No, a new sample is needed for each testing
A) Yes, a new sample would not be needed Compatibility testing may be performed on a patient sample within 3 days of the scheduled transfusion. However, if the patient is pregnant or was transfused within 3 months, the sample must be less than 3 days old
What ABO type is found in group A1 individuals following deacetylation of their A antigens? A) acquired B B) B(A) C) A(mod) D) A(int)
A) acquired B In a group A patient, Acquired B should be suspected when the patient initially types as group AB but with a weaker expression of the B antigen in the ABO red cell testing. To resolve Acquired B one needs to repeat the typing with a second source of antibody or acidified human anti-B. [AABB Tech Manaul 2017, p273]
Which of the following is most helpful to confirm a weak ABO subgroup? A) adsorption-elution B) neutralization C) testing with A1 lectin D) use of anti-A,B
A) adsorption-elution Adsorption and elution techniques are used to detect ABO antigens that are not detectable by direct agglutination. The cells are incubated with the antibody (anti-A or anti-B) to the antigen expected on the red cells. An elution method is performed and the antibody in the eluate is tested for recovering anti-A (or anti-B depending on the specificity that was used in the adsorption). [AABB Tech Manual 2017, p272]
Patient Blood Type O Can receive PLASMA from who?
A, B, AB, O
Patient Blood Type AB Can receive PLASMA from who?
AB ONLY
Blood Group AB
Antigen on RBC A and B Phenotype AB Genotype AB ANTIBODIES in Serum None
A 26-year-old B Rh (D)-NEGative female patient requires a transfusion. No B Rh (D)-NEGative donor units are available. Which should be chosen for transfusion? A) B Rh (D)-POSitive RBCs B) O Rh (D)-NEGative RBCs C) AB Rh (D)-NEGative RBCs D) A Rh (D)-NEGative RBCs
B
Characteristics of antibodies of the ABO blood group system include all of the following except: A) Naturally occurring B) Present at birth C) Mainly IgM class C) Activate complement
B
The purpose of the immediate spin crossmatch is to: A) ensure survival of transfused RBCs B) determine ABO compatibility between donor and recipient C) detect cold-reacting unexpected antibodies D) meet computer crossmatch requirements
B
In an Emergency situation, what type of blood should be given to a female patient of child-bearing age if the ABO group and Rh type are unknown? A) Group O, Whole Blood should be given B) Group O, Rh-NEGative red cells should be given C) Group O, Rh-POSitive red cells should be given D) Group O, Washed Red Blood Cells should be given
B) Group O, Rh-NEGative red cells should be given In an emergency situation, group O red cells are given if the patient's ABO and Rh are unknown. In the case of women with child-bearing potential, it is preferential to provide group O, Rh-NEGative red cells. [AABB Tech Manual 2017, p478; Harmening 2012, p361]
An antibody screen is reactive at IAT phase of testing using a three-cell screen and the autocontrol is negative. What is a possible explanation for these results? A) a cold alloantibody B) High frequency alloantibody or a mixture of alloantibodies C) a warm autoantibody D) a cold and warm alloantibody
B) High frequency alloantibody or a mixture of alloantibodies High frequency alloantibodies or a mixture of alloantibodies may cause all three screening cells to be positive. A negative autocontrol would rule out autoantibodies
When may an IS crossmatch be performed? A) When a patient is being massively transfused B) When there is no history of antibodies and the current antibody screen is negative C) When blood is being emergency released D) When a patient has not been transfused in the past 3 months
B) When there is no history of antibodies and the current antibody screen is negative The IS crossmatch may be performed when the patient has no history of antibodies and the current antibody screen is negative.
The following results were obtained in pretransfusion testing: 37C SCI: 0 SCII: 0 AC: 0 IAT SCI : 3+ SCII: 3+ AC: 3+ The most probable cause of these results is: A) rouleaux B) a warm autoantibody C) a cold autoantibody D) multiple alloantibodies
B) a warm autoantibody Presence of agglutination at AHG phase with both screening cells and autocontrol is indicative of warm autoantibody. [Harmening 2012, p222]
What is the minimum number of patient identifiers that must be included on a request for transfusion? A) one B) Two C) Three D) four
B?
Name That Blood Group! Antigen on RBC A Phenotype A Genotype AA orAO ANTIBODIES in Serum B
Blood Group A
Name That Blood Group! Antigen on RBC B Phenotype B Genotype BB or BO ANTIBODIES in Serum A
Blood Group B
Name That Blood Group! Antigen on RBC H Phenotype O Genotype OO ANTIBODIES in Serum A, B, and AB
Blood Group O
Name That Blood Group! Antigens (on the surface of the red blood cells): B indicates there are B antigens. Rh+ indicates there are Rh antigens. Antibodies (in the blood plasma): A antibodies. If there are B and Rh antigens but no A antigens, then the antibodies in the blood plasma are A antibodies.
Blood type B Rh+ (Image Source: https://educationalgames.nobelprize.org/educational/medicine/bloodtypinggame)
The following test results are noted for a unit of blood labeled group A, Rh-NEGative: cells tested with anti-A: 4+ anti-B: 0 anti-D: 3+ What should be done next? A) transfuse as a group A, Rh-NEGative B) transfuse as a group A, Rh-POSitive C) notify the collecting facility D) discard the unit
C) notify the collecting facility A serological test to confirm the ABO on all RBC units and Rh on units labeled as Rh-NEGative must be performed prior to transfusion. Any errors in labeling must be reported to the collection facility. [AABB Tech Manual 2017, p 458]
During an emergency situation with no time to determine ABO group and Rh type on a current sample for transfusion, it is noted that previous records state the patient is known to be A, Rh-NEGative. The CLS should: A) refuse to release any blood until the patient's sample has been typed B) release A Rh-NEGative Red Blood Cells C) release O Rh-NEGative Red Blood Cells D) release O Rh-POSitive Red Blood Cells
C) release O Rh-NEGative Red Blood Cells Emergent release of blood CANNOT use previous records. Blood typing must be performed on the current sample. In this case, group O Rh-NEGative is the best choice since there is evidence the patient is Rh-NEGative. [AABB Tech Manual 2017, p478]
Crossmatch results at the antiglobulin phase were NEGative. When 1 drop of check cells was added, no agglutination was seen. The most likely explanation is that the: A) red cells were overwashed B) centrifuge speed was set too high C) residual patient serum inactivated the AHG reagent D) laboratorian did not add enough check cells
C) residual patient serum inactivated the AHG reagent A negative reaction after the addition of check cells indicates AHG serum was not present. Inadequate washing of red cells may leave residual patient serum behind, which can neutralize AHG serum. [Harmening 2012, p 112]
The purpose of testing with anti-A,B is to detect: A) anti-A1 B) anti-A2 C) subgroups of A D) subgroups of O
C) subgroups of A A(x) cells react more strongly with anti-A,B than with anti-A. If anti-A is nonreactive, A(x) cells may be detected with anti-A,B. [AABB Tech Manaul 2017, p 296]
What is an Electronic Crossmatch?
Comparison of donor and patient ABO groups and serologic data from a computer file
You just received a request and sample for pre-transfusion testing. Which is the most appropriate to do first? A) perform the ABO grouping and Rh typing B) complete the crossmatch C) perform the IAT to see if the patient is going to be a problem D) check the records for prior type and screen results on the page
D
Which of the following is NOT a requirement for the electronic crossmatch? A) The computer system contains logic to prevent assignment and release of ABO incompatible blood B) There are concordant results of at least two determinations of the recipient's ABO type on record, one of which is from the current sample C) Critical elements of the system have been validated on site D) There are concordant results of at least one determination of the recipient's ABO type on file
D) There are concordant results of at least one determination of the recipient's ABO type on file ABO determinations must be concordant on at least two occassions, including the current sample.
Which of the following would most likely be responsible for an incompatible antiglobulin crossmatch? A) recipient's red cells possess a low-frequency antigen B) anti-K antibody in donor serum C) recipient's red cells are polyagglutinable D) donor red cells have a positive direct antiglobulin test
D) donor red cells have a positive direct antiglobulin test Since crossmatching is a test between the patient's plasma and donor's cells, any incompatibility is due to the donor's red cells. If a patient is negative for clinically significant antibodies to common antigens, an incompatible unit by the antiglobulin test is due to either a POSitive DAT on the donor's red cells or the patient has an antibody to a low-incidence antigen that the donor's cells possess. [AABB Tech Manual 2017, p487]
The process of separation of antibody from its antigen is known as: A) diffusion B) adsorption C) neutralization D) elution
D) elution An elution is the process of removal of antibody from red blood cells. The product of the elution method is an eluate. The eluate contains the antibody and can be used in antibody identification methods. [Harmening 2012, p454]
A patient is group A, Rh-POSitive but is recieving Group O, bone marrow transplant (BMT) on Friday. After the transplant, what hemagglutination pattern will the patient demonstrate when the patient's red cells are tested with anti-A? A) rouleaux B) aggregation C) polyagglutination D) mixed-field
D) mixed-field 2 cell populations may lead to a mixed-field agglutination pattern. Mixed-field may occur from transfusion, stem cell transplant or rare genetic chimera. A chimera is a person with a dual population of cells derived from more than one zygote. [AABB Tech Manual 2017, p275]
The major crossmatch will detect a(n): A) group A patient mistyped as group O B) unexpected red cell antibody in the donor unit C) Rh-NEGative donor unit mislabeled as Rh-POSitive D) recipient antibody directed against antigens on the donor red cells
D) recipient antibody directed against antigens on the donor red cells The major crossmatch tests the recipient's plasma with donor's cells. This would detect any antibody in the recipient that would react with antigens on the donor's RBCs. If a patient were mistyped as a group O rather than group A, then group O cells would be selected for crossmatch and no incompatiblity would be found. [AABB Tech Manual 2017, p 461]
What routine tests are done on the infant after delivery? What tests are not necessary to do on the infant?
Done ABO/Rh DAT weak D Not Done Reverse type Antibody screen
A crossmatch is positive at AHG phase with poly specific AHG reagent but is negative with mono specific anti-IgG AHG reagent. This may indicate the antibody: A) is a weak anti-D B) is a clinically insignificant Lewis antibody C) can cause decreased survival of transfused RBCs D) is a Kidd antibody E) Both Answers B and D are correct F) Both Answers C and D are correct
E
A nurse just called to request additional RBC units for patient for whom he performed compatibility testing four days ago. They would like to use the original specimen as you keep it for seven days anyway your most appropriate course of action would be to: A) check to see if there is enough of the original specimen B) perform the compatibility testing on the original specimen C) requested new specimen in case the patient has developed a clinically significant unexpected antibody D) indicate that a new specimen is necessary because the patient has been recently transfused E) Both Answers C and D are correct F) Both Answers A and C are correct
E
Which is true of Rouleaux formation? A) It is a stacking of RBCs to form aggregates B) It can usually be dispersed by adding saline C) It can appear as an ABO incompatibility D) It can cause a false-POSitive immediate spin crossmatch E) All of the above
E
Which represents requirements set forth by the AABB for the performance of a computer crossmatch? A) computer system must be validated on-site B) recipient antibody screen be negative C) two determinations of the recipient ABO and Rh must be performed D) computer system must have logic E) all the above
E
Fill in the Blank When computer selection of ABO-compatible red blood cells is utilized in transfusion services, this is also called __________________________________________________.
Electronic crossmatching
Fill in the Blank WAIHA are usually _____ autoantibodies of the _____ blood group. A common one to find is auto-anti-____?
IgG Rh e
When is a historical record check performed?
Every patient Every time
List two ways that exposure to foreign red blood cell antigens can occur:
Exposure to foreign red blood cell antigens can occur through: 1) blood transfusion or 2) pregnancy
True or false if a patient has WAIHA, it can just be ignored because it won't lyse transfused blood.
FALSE
What does Immediate spin (IS) phase testing predict?
Immediate spin (IS) phase testing is performed to detect any ABO incompatibilities
Patient Blood Type O Can receive RBCs from what types?
O ONLY
Invesigation of Incompatible Major Crossmatches Observations: Crossmatch: POSitive Auto-control: NEGative Antibody screen: POSitive
Possible interpretations - Donor unit may have a positive DAT -Alloantibody in patient's serum reacting with antigens on donor's cells and screening cells Comments: -Perform DAT on donor unit; if positive, do not use the unit -Perfom antibody identification studies on patient's serum and repeat crossmatch using units negative for the corresponding antigen
Invesigation of Incompatible Major Crossmatches Observations: Crossmatch: POSitive Auto-control: POSitive Antibody screen: POSitive
Possible interpretations - Both an autoantibody and alloantibody may be present in the patient's serum -Abnormalities in the patient's serum owing to imbalance of A/G ratio ---plasma expanders ---caprylate antibodies ---contaminants Comments:
Invesigation of Incompatible Major Crossmatches Observations: Crossmatch: POSitive Auto-control: NEGative Antibody screen: NEGative
Possible interpretations -incorrect ABO grouping of patient or donor -patient serum may contain an ABO antibody -Alloantibody in patient's serum reacting with antigen donor's red cells but not present on screening cells Comments: -Repeat ABO grouping: verified identity of sample -Check patient sample sample for subgroups; check patient's transfusion and transplantation histories
What is an Abbreviated Crossmatch?
TYSC plus an IS XM
What is a serologic crossmatch?
Testing that occurs when donor red blood cells are physically tested against the recipient/patient plasma is called a serologic cross-match.
How do you do a crossmatch for newborn transfusion?
Tests the maternal serum or cord blood serum against the proposed donor unit
What is AHG?
The Antiglobulin crossmatch procedure begins in the same manner as the IS XM, continues to a 37C incubation, and finishes with an antiglobulin test.
When should the antiglobulin crossmatch technique be selected to determine the compatibility between donor blood and recipient plasma?
The antiglobulin crossmatch procedure should be selected when a recipient has a clinically significant antibody or has a known history of having an antibody
What phases of testing are used in the immediate spin (IS) and antiglobulin (IAT) crossmatching procedures?
The immediate spin crossmatch includes the IS phase of testing. The antiglobulin (IAT) crossmatch includes the IS, 37, and AHG test phases
What is plasma?
The liquid portion of whole blood, containing water, electrolytes, glucose, fats, proteins, and gases. It contains all the clotting factors necessary for coagulation but in an inactive form. Once coagulation occurs, the fluid is converted to serum.
When testing a DAT, why should the sample be collected in EDTA?
This inhibits complement activation so the DAT will be positive because of IgG and not complement
True or False The transfusing facility is required by the AABB Standards to confirm the ABO cell grouping on all units and Rh typing on units labeled Rh-NEGative. Repeat Weak-D testing is NOT required.
True
When can an Immediate Spin crossmatch be used?
only if No alloantibody has been currently or historically identified
What is expected to occur with transfusion of ABO incompatible donor RBCs?
very severe (often fatal) Acute Hemolytic Transfusion Reactions. The incompatible donor RBCs will be destroyed by the recipient almost immediately via complement activation (intravascular hemolysis of the donor RBCs).