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Serology and Immunohematology

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Two serology test methods are agglutination, enzyme linked immunosorbent assay. ... Serology tests are easier to perform and provide results more quickly, but ... – PowerPoint PPT presentation

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Title: Serology and Immunohematology


1
Chapter 46
  • Serology and Immunohematology

2
Introduction
  • Serology is the study of antigens and antibodies
  • Immunohematology refers to testing done in blood
    banks on red blood cells
  • All testing requires the use of Standard
    Precautions

3
Antigens and Antibodies
  • Antigens are substances recognized as foreign by
    the body
  • Antibodies are proteins produced by the body in
    response to specific antigens

4
Checkpoint Question 1
  • How would you describe a test that is both
    specific and sensitive?

5
Answer
  • A test that is specific and sensitive can measure
    a substance even if only a tiny amount is present
    (specificity), and it can pick that substance out
    of a solution containing millions of other
    related substances (sensitivity).

6
Serology Test Methods and Principles
  • Agglutination of visible particles
  • Enzyme linked immunosorbent assays (ELISA)
  • Other methods
  • Agglutination inhibition
  • Competitive binding assays

7
Agglutination Test
  • Mix together reagent and sample on paper card or
    glass plate
  • Gently rock reagent and sample back and forth
  • Observe for agglutination

8
Agglutination Test (continued)
  • If specific antigen is in reagent, then serum can
    be tested for the specific antibody
  • Infectious mononucleosis
  • Rheumatoid arthritis
  • Syphilis
  • Rubella.
  • If reagent has antibody attached, then specimen
    can be tested for specific antigen
  • Streptococci

9
Enzyme Linked Immunosorbent Assays
  • ELISA tests come with necessary reagents packaged
    in a kit
  • Be sure to follow manufacturers instructions
  • Results are easy-to-read color change

10
Checkpoint Question 2
  • What are two serology test methods, and how do
    they indicate the presence of the test substance?

11
Answer
  • Two serology test methods are agglutination,
    enzyme linked immunosorbent assay. Enzyme
    immunoassays produce a color change. With
    agglutination tests, clumping of particles
    (agglutination) occurs if the test substance is
    present.

12
Reagent and Kit Storage and Handling
  • Kits must be stored at temperature recommended on
    box
  • Room temperature
  • Refrigerator
  • Reagents should never be used past expiration
    date
  • Follow specific specimen collection guidelines
    for each kit

13
Checkpoint Question 3
  • Why is it important to store reagent kits at
    specified temperatures?

14
Answer
  • Improperly stored kits may result in
    deterioration of the reagents, which may lead to
    false test results.

15
Following Test Procedures
  • Test principle and clinical use of test
  • Reagents and materials needed to do test
  • Precautions
  • Specimen collection and handling
  • Controls to be run and how often

16
Following Test Procedures (continued)
  • Step-by-step procedure to follow
  • Interpretation and reporting of results
  • Normal or expected values
  • Test limitations

17
Quality Assurance and Quality Control
  • Kits should be tested periodically for continued
    stability of all reagents
  • Quality control (QC) test needs to be performed
    each time the reagents are used

18
External Controls
  • Solution similar to a patient sample is tested a
    patient sample
  • Its value or expected result is already known
  • If controls do not give the expected result,
    patient results should not be reported

19
Internal Controls
  • Technique controls are built into the test packs
  • Monitor that test procedure is followed correctly
    and reagents are working properly
  • Do not report patient results if controls do not
    give proper reactions

20
Serology Tests
  • Many serological tests exist
  • Some common tests are performed in medical office

21
Rheumatoid Factor/Rheumatoid Arthritis
  • Autoimmune progressive inflammatory disease of
    the joints
  • Test for agglutination
  • False-negative result
  • Negative result when patient does have disease
  • False-positive result
  • Positive result when patient does not have disease

22
Checkpoint Question 4
  • What is the difference between a false-negative
    and a false-positive test result, and why do
    these sometimes occur?

23
Answer
  • A false-negative result occurs when a patient
    tests negative for a disease, even though the
    disease is present. A false-positive result
    occurs when a test indicates that a patient has a
    particular disease, even though the patient is
    disease free. These results can be caused by
    technical problems in performing the test or by
    the patients biologic condition.

24
Infectious Mononucleosis
  • Caused by Epstein-Barr virus
  • Testing
  • Agglutination of RBCs or latex particles
  • ELISAs
  • Results
  • False-negative early in the disease
  • False-positive results by waiting too long to
    read agglutination tests

25
Rapid Plasma Reagin Test for Syphilis
  • Sexually transmitted disease caused by Treponema
    pallidum
  • RPR is agglutination test
  • Physician and health department must be notified
    of reactive results for syphilis

26
Pregnancy Test
  • Based on detection of human chorionic
    gonadotropin (HCG)
  • Testing
  • Agglutination
  • ELISA
  • Urine or serum is added to test pack
  • Internal positive and negative control areas must
    react appropriately for valid results

27
Group A Streptococcus
  • One of most common bacterial causes of sore
    throat and upper respiratory tract infections
  • Testing
  • Bacterial culture
  • Agglutination
  • ELISA

28
Checkpoint Question 5
  • What are the benefits and drawbacks of using
    serology tests versus cultures for group A
    streptococcus?

29
Answer
  • Serology tests are easier to perform and provide
    results more quickly, but cultures are considered
    to be more sensitive.

30
Immunohematology
  • Determines if donor blood is compatible for
    transfusion
  • If compatible, RBCs circulate in recipients body
    for longer time
  • If incompatible, recipients body will begin
    destroying donor blood
  • Rapidly leads to death

31
Blood Group Antigens
  • Transfusion compatibility determined by testing
    antigens present on donor and recipient RBCs and
    antibodies present in recipients serum
  • ABO group
  • Rh type
  • Other blood groups

32
ABO Group
  • Four blood groups A, B, O, or AB
  • Almost all serum contains antibodies to ABO
    antigens it lacks
  • Antibodies are crucial to safe transfusion

33
Rh Type
  • Rh group includes antigens D, E, C, e, c
  • Presence of D antigen is Rh positive
  • Absence is Rh negative
  • Antibodies to D do not occur naturally

34
Rh Type (continued)
  • Those lacking D antigen must be exposed to D
    antigen of foreign RBCs to produce antibodies
  • Rh-negative patient is transfused with
    Rh-positive blood
  • Rh-negative mother is exposed to Rh-positive
    cells of her baby before or during childbirth

35
Other Blood Groups
  • Other RBC antigens
  • Duffy, Lewis, MNS, Kidd, Kell
  • White blood cells and platelets also have
    antigens
  • Human leukocyte antigens

36
Blood Group Testing
  • ABO Testing
  • Direct or forward typing
  • Indirect or reverse typing
  • Rh Testing
  • Anti-D reagent is used to determine the Rh of
    RBCs

37
Checkpoint Question 6
  • Which ABO blood group is the universal donor?
    What does this mean?

38
Answer
  • Type O is the universal donor because it lacks A
    or B antigens, making it safe to give patientsno
    matter what their ABO group.

39
Blood Supply
  • American Red Cross and other agencies collect
    donor blood
  • Shortage of donor blood
  • Donor blood divided into three products
  • 1. Packed RBCs
  • 2. Plasma
  • 3. Platelet concentrates

40
Checkpoint Question 7
  • What are three products that can be obtained from
    1 U whole blood and how are they used?

41
Answer
  • A single unit of whole blood can be divided into
    packed RBCs (used to treat anemia) plasma (used
    to treat bleeding from a lack of coagulation
    factors) and platelet concentrates (used to
    treat bleeding caused by low platelet count or
    dysfunctional platelets).
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