chapter 49. quiz 6. Compatibility Testing and emergency transfusion

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Questions and Answers

Why are compatibility tests like ABO-Rh type, antibody screen, and crossmatch important in blood transfusions?

To identify the patient's blood type for aesthetic purposes

To increase the cost of medical procedures

To speed up the blood transfusion process

To demonstrate harmful antigen-antibody interactions in vitro (correct)

Why must donor blood undergo screening before an emergency transfusion of type-specific blood?

To check for hemolytic anti-A and/or anti-B antibodies, and Rh antibodies (correct)

To increase the volume of blood available for transfusion

To save time during the transfusion process

To test for the presence of all blood types

Why is proper selection of donor blood through a crossmatch necessary?

To avoid testing for unexpected antibodies

To increase the cost of blood transfusions

To test for compatibility between recipient blood and donor blood (correct)

To speed up the blood bank procedures

Why is determination of the patient’s correct blood type exceedingly important?

Accidental transfusion of ABO-incompatible blood can lead to serious and tragic reactions Signup and view all the answers

What percentage of all transfusion-related deaths are related to hemolytic reactions due to antibody incompatibility?

15% Signup and view all the answers

What is the percentage of Rh(D)-negative patients who may produce anti-D antibodies when given Rh(D)-positive blood?

60% to 70% Signup and view all the answers

what is the percentage of individuals possess the D antigen and are classified as Rh(D) positive

85% Signup and view all the answers

What may happen if Rh(D)-positive blood is transfused to a Rh(D)-negative patient with Rh(D) antibodies?

The patient may develop hemolytic transfusion reaction. Signup and view all the answers

What percentage of individuals lack the D antigen and are classified as Rh(D) negative?

15% Signup and view all the answers

Which antigen, apart from A and B antigens, is very common and likely to produce immunization according to the text?

D antigen Signup and view all the answers

What type of RBCs are used in antibody screens to avoid reacting with anti-A or anti-B antibodies?

Type O RBCs Signup and view all the answers

Why are reagent RBCs used in antibody screens typically of type O?

To avoid reacting with patient's serum antibodies Signup and view all the answers

Which immunoglobulin (Ig) is most commonly associated with alloantibodies and requires an indirect antiglobulin test for detection?

IgG Signup and view all the answers

What is the purpose of adding an additive that promotes antibody binding in the indirect antiglobulin test?

To assist in detecting IgG antibodies attached to RBCs Signup and view all the answers

What occurs if an antibody screen is positive during blood donation testing?

Follow-up testing is required to identify the specific target antigen Signup and view all the answers

Why is it important to screen donor serum for unexpected antibodies before transfusion?

To prevent introduction of harmful antibodies into the recipient's circulation Signup and view all the answers

What is the primary purpose of the immediate spin (IS) phase in a crossmatch process?

Detect ABO incompatibilities and naturally occurring antibodies in MN, P, and Lewis systems Signup and view all the answers

In which phase of the crossmatch process are antibodies in the Rh system primarily detected?

Indirect Coombs phase Signup and view all the answers

Why is an abbreviated crossmatching process sometimes used during emergency situations?

To eliminate reactions from human errors in ABO-Rh typing alone Signup and view all the answers

What is the specific focus of the indirect antiglobulin phase in a crossmatch process?

Detection of antibodies in the Rh system and non-ABO blood group systems Signup and view all the answers

Why is it important to detect antibodies in the Rh system during a crossmatch process?

To prevent hemolytic reactions due to unexpected antibodies Signup and view all the answers

What is the purpose of incubating the test tube at 37°C in albumin or low-ionic strength salt solution?

To detect incomplete antibodies or antibodies able to attach to a specific antigen Signup and view all the answers

What is the purpose of the antiglobulin phase in blood group testing?

To detect most incomplete antibodies in blood group systems Signup and view all the answers

Why are the incubation and antiglobulin phases considered important?

To identify antibodies capable of causing serious hemolytic reactions Signup and view all the answers

What is the significance of washing and resuspending RBCs after observation for hemolysis and agglutination?

To remove unbound immunoglobulins from the solution Signup and view all the answers

Why is it important to perform an immediate-phase crossmatch when using uncrossmatched blood in emergency situations?

To detect unexpected antibodies directed against antigens in the MN, P, and Lewis systems. Signup and view all the answers

What is the primary purpose of an abbreviated format for blood testing during urgent transfusions?

To provide potentially life-saving blood products quickly. Signup and view all the answers

What is the purpose of adding the patient's serum to donor RBCs during an incomplete crossmatch?

to detect unexpected antibodies outside the ABO systems Signup and view all the answers

What is the purpose of obtaining at least an ABO-Rh typing when using uncrossmatched blood?

To identify potential errors that may occur in ABO typing. Signup and view all the answers

Why is it crucial to perform an immediate-phase crossmatch when using uncrossmatched group O blood?

To detect unexpected antibodies outside the ABO systems. Signup and view all the answers

Why do investigators caution against the indiscriminate use of uncrossmatched blood, despite its historical safety record?

Even though it's usually safe, there is still potential for serious reactions. Signup and view all the answers

Why are ABO-Rh type-specific transfusions more likely to be successful for individuals who have never been exposed to foreign RBCs?

They tend to have fewer antibodies against A and B antigens. Signup and view all the answers

Why is it important to determine the patient’s ABO-Rh type during hospitalization before administering type-specific blood?

To ensure compatibility with any antibodies the patient may have developed. Signup and view all the answers

What is the significance of using type O Rh-negative uncrossmatched PRBCs over whole blood?

Smaller plasma volume and almost free of hemolytic anti-A and anti-B antibodies Signup and view all the answers

Why do some type O donors pose a risk when donating whole blood for transfusion?

High titers of hemolytic anti-A and anti-B antibodies Signup and view all the answers

What is the purpose of an emergency-release pack of uncrossmatched O negative RBCs in some hospitals?

For immediate availability in urgent situations Signup and view all the answers

In which scenario would a massive transfusion protocol (MTP) be activated in a hospital?

For patients requiring large volumes of blood products Signup and view all the answers

Why is it essential for blood banks to ensure type O blood is free of hemolytic anti-A and anti-B antibodies before transfusion?

To prevent adverse reactions in non-type O recipients Signup and view all the answers

What sets type O Rh-negative PRBCs apart from other blood products in terms of antibody risk?

Practically free of hemolytic anti-A and anti-B antibodies Signup and view all the answers

What is the consequence of switching a patient who received more than 2 units of type O Rh-negative whole blood to their correct blood type too soon?

High risk of major intravascular hemolysis Signup and view all the answers

Why is it unsafe to transfuse a patient with their correct blood type immediately after receiving more than 2 units of O Rh-negative whole blood?

Risk of causing major hemolysis due to high levels of anti-A and anti-B Signup and view all the answers

What are the potential consequences of continuing to use O Rh-negative whole blood in a patient who has received more than 2 units?

Minor hemolysis of recipient RBCs and hyperbilirubinemia Signup and view all the answers

Why must the blood bank determine safe levels of anti-A and anti-B before transfusing a patient with their correct blood type?

To prevent major intravascular hemolysis Signup and view all the answers

Study Notes

Uncrossmatched Blood

Uncrossmatched, type-specific blood can be used in emergency situations where there is no time for compatibility testing.
However, caution should be used for patients who have previously received transfusions or have been pregnant.
Historically, the military has used uncrossmatched blood in emergencies with no serious consequences.

Type O Rh-Negative Blood

Type O Rh-negative blood lacks A and B antigens and cannot be hemolyzed by anti-A or anti-B antibodies in the recipient's plasma.
Type O Rh-negative blood can be used for transfusions when typing or cross-matching is not available.
However, some Type O donors produce high titers of hemolytic IgG, IgM, anti-A and anti-B antibodies that can cause destruction of A or B RBCs in non-Type O recipients.

Compatibility Testing

The ABO-Rh type, antibody screen, and crossmatch are referred to as compatibility tests.
These tests are designed to demonstrate harmful antigen-antibody interactions in vitro to prevent in vivo interactions.
Donor blood used for emergency transfusions must be screened for hemolytic anti-A and/or anti-B antibodies and Rh antibodies.
Recipient blood must undergo ABO-Rh typing and testing for unexpected antibodies.

ABO-Rh Typing

Determination of the patient's correct blood type is crucial to prevent ABO-incompatible blood transfusions, which can cause serious and tragic reactions.
15% of all transfusion-related deaths are due to hemolytic reactions caused by antibody incompatibility.

Type-Specific, Partially Crossmatched Blood

When using uncrossmatched blood, it is best to obtain at least an ABO-Rh typing and an immediate-phase crossmatch.
This incomplete crossmatch can eliminate serious hemolytic reactions resulting from errors in ABO typing.

Antibody Screening

Antibody screens are performed to identify unexpected RBC alloantibodies.
The patient's serum is combined with commercially supplied RBCs that express RBC antigens for which clinically significant alloantibodies are formed.
An indirect antiglobulin test is undertaken to evaluate the presence of IgG alloantibodies.

Crossmatching

A crossmatch is a trial transfusion within a test tube to detect potential transfusion reactions.
The full crossmatch can be completed in 45 to 60 minutes and is performed in three phases: an immediate spin phase, an incubation phase, and an indirect antiglobulin phase.
The immediate spin phase detects ABO incompatibilities and those caused by naturally occurring antibodies in the MN, P, and Lewis systems.

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Description

Learn about the general principles of compatibility testing in blood transfusions. Understand the importance of ABO-Rh typing, antibody screening, and crossmatching to prevent harmful antigen-antibody interactions.