Category: Patient

Includes compatibility testing (AHG, electronic, immediate-spin), antigen typing, antibody screening and identification, direct antiglobulin testing, elution, transfusion reaction and drug reaction workups, component typing tests upon receipt in hospital blood bank, release and return of components

Contacting the Transfusion Physician with Transfusion Reaction Workup Results

drzeyd

Principle:

The physician on-call for the blood bank requires a certain minimum amount of data to determine the significance of a suspected transfusion reaction and to decide if further testing is required.

Policy:

  1. DO NOT call the transfusion physician about a transfusion reaction until the following data is ready:
    1. Patient name and hospital number
    2. Patient age and diagnosis and location
    3. Previous transfusion history including antibodies and previous transfusion reactions
    4. Vital signs (BP, temperature, pulse, and respiratory rate) before AND after the transfusion
    5. Clinical symptoms (e.g. fever, chills, rash, urticaria, dyspnea, hematuria, etc.)
    6. Repeat ABO and D type on the post-transfusion specimen
    7. Direct antiglobulin/Coombs test (DAT) on the post-transfusion specimen
    8. DAT on the pretransfusion specimen if the post-transfusion specimen is DAT-positive
    9. Results of hemolysis check on pre- and post-transfusion plasma/serum
  2. The transfusion physician may order additional testing based on the above results.

My Opinion: Use Gamma-Heavy-Chain-Specific AHG Reagent

drzeyd

There are many types of antiglobulin reagent available which have differing specificities to immunoglobulins (e.g. whole molecule IgG, IgG-heavy-chain specific, IgM-heavy-chain-specific, IgA-heavy-chain-specific) and complement fragments (e.g. C3b, C3c, C3d).

For the purpose of antibody identification using the indirect antiglobulin test IAT, normally polyspecific, whole molecule IgG, and/or gamma-heavy-chain-specific reagents are used.

The purpose of antibody identification is normally to detect clinically significant antibodies—NOT ALL ANTIBODIES.  In a busy hospital blood bank, I am not routinely interested in detecting cold antibodies that do not react at 37C.

Polyspecific reagents will detect both complement and/or immunoglobulin and are commonly chosen.  However, the complement may detect insignificant cold antibodies that may obscure clinically significant IgG antibodies.

A whole-molecule IgG reagent is not really monospecific since it detects both heavy and light chains.  The light chains (kappa and lambda) are shared by all classes of immunoglobulin.  Thus, an IgM antibody (usually cold) may show weak reactivity—nonspecific cold antibodies may be detected!

My usual choice is to routinely use a gamma-heavy-chain-specific reagent.  I have been using this for many years and it expedites the workflow.  The likelihood of missing a clinically significant antibody is rare.  In my long career, I have only detected a small number of Kidd antibodies that required a polyspecific reagent with complement. 

If there is a nonspecific antibody, I will check the Jka and Jkb typings.  If either is negative, I will check for an antibody showing dosage and consider using a polyspecific reagent.  I have previously reported such an antibody in an earlier post—it is extremely rare!

Another consideration is the detection of interference from a new chemotherapy reagent, anti-CD47.  This nonspecific reactivity will be eliminated by using a gamma-heavy-chain specific reagent:

This is an example of a nonspecific reagent using whole molecule IgG AHG:

Here is the same sample using gamma-heavy-chain-specific AHG:

4/10/20

Projective Exercise 8 Solution: D-positive with anti-D

drzeyd

Some Possible Explanations:

Always review the transfusion history of all component types, medication history, and the clinical history!! Start with this first.

  1. Receipt of plasma with anti-D (RhIG, IVIG, etc.)–passive antibodies
  2. Partial D with anti-D:
    1. Partial or mosaic D patient who received D positive RBCs and made anti-D directed against its missing epitopes
  3. Anti-G:
    1. Not all anti-G is anti-C and anti-D:  It is really a separate specificity.  It is possible that anti-G may be made even though the patient is C-positive.
  4. Anti-LW:
    1. However, it is unlikely to show such strong reactions

Can you think of other explanations?

3/10/20

Policy: Delayed Hemolytic/Serologic Transfusion Reactions

drzeyd

Principle:

Unlike acute hemolysis, delayed hemolysis may be insidious and develop over days to weeks.  Likewise severity may vary from asymptomatic but only laboratory-detectable (i.e. delayed serologic reaction) to life-threatening only a few days after transfusion (e.g. an amnestic response to anti-Jka that was undetectable in the compatibility testing several days previously).

Remember that the most severe reactions may occur with weak or negative reactions!!

Policy:

  1. In the first encounter of each patient with a positive direct antiglobulin test (DAT), the workup must include an acid-elution.
  2. Perform a DAT on patients with dropping hemoglobin levels not attributable to trauma, i.e. an anatomic defect.
  3. Obtain the full clinical history, medication history, and transfusion history (including at outside institutions)
    1. Check previous transfusion history.
  4. Send the DAT results (poly, IgG, C3d) and acid-elution to the Head, Transfusion Medicine or the Transfusion Medicine Physician covering the service.
    1. If the polyspecific DAT is positive, but only the monospecific C3 is non-negative, check with the Transfusion Medicine physician whether to perform the elution.
    2. He will write an interpretative report/comment appended to the DAT results in Hematos IIG.
  5. It is the decision of the Transfusion Medicine Physician preparing the report to decide if the clinician needs to be contacted.

References:

  1. Standards for Blood Banks and Transfusion Services, Current Edition, AABB, Bethesda, MD, USA
  2. Guidelines to the Preparation, Use, and Quality Assurance of Blood Components, European Committee (Partial Agreement) on Blood Transfusion (CD-P-TS), Current Edition

Projective Exercise 8

drzeyd

As a transfusion medicine physician, I must know if I can trust my staff’s interpretation of immunohematology testing.  I may be called at night and they will provide me with results and I must use these to make a medical judgment.  If their interpretation is flawed, I might make a decision that harms the patient.

I really don’t like multiple-choice questions, but nowadays this is often the norm.  For my staff, especially senior staff and those who want to be promoted to senior staff, I have developed a series of projective exercises to help me understand their thought processes.  I emphasize that I do not want a mere regurgitation of isolated facts:  I want integration of the facts into useful information!!

The following is my favorite assessment, offered to advanced staff and candidates for senior technologist, supervisors, and technical manager positions.  Usually, these staff have SBB, ART, FIBLS or equivalent qualifications.

You are reviewing abnormal test results and receive the following case:

Anti-A:           4+

Anti-B:           0

Anti-A,B        4+

A1 cells         0

B cells           3+

Anti-D            3+

D-control      0

Antibody Screen:  3+ in SC1 (R1R1), 4+ in SC2 (R2R2), 0 in SC3 (rr)

Antibody Identification:  Anti-D

Give possible explanation(s) for this situation.  Request any additional information you need.

What blood type will you transfuse?

Solution will follow in a subsequent post.

30/9/20

Direct Antiglobulin Test and Selection of RBC Units for Transfusion

drzeyd

Principle:

In 1984 effective with the 13th Edition AABB Standards, the requirements for performing a direct antiglobulin test and autocontrol for compatibility testing were eliminated.  The DAT is very important to detect delayed hemolytic transfusion reactions, certain autoimmune conditions, and drug-related hemolysis.

Since that time, the immediate-spin crossmatch and now the electronic computer paperless crossmatch may be used for most compatibility testing in place of the classic, antiglobulin-phase (indirect antiglobulin test) crossmatch.

If an antiglobulin phase (IAT) crossmatch is performed, an RBC unit with a positive DAT will cause a false-positive reaction.  Since most crossmatching does not include the IAT, it will not be affected by the DAT status of a donor unit.

Policy:

  1. Donor RBC units will NOT be routinely tested for DAT as part of component processing.
  2. The type of compatibility testing selected for a particular patient should be the technically simplest one (no need to do extra work unless so instructed by the transfusion medicine consultant/designate):
  3. Do a full antiglobulin-phase IAT crossmatch if ANY of the following applies:
    1. There are no two independent ABO/D typings on the patient during the current admission.
    2. The ABO/D type of the current admission does not match the historical information.
    3. The patient has a detectable antibody at 37C
    4. The patient has a history of a clinically significant antibody but no current antibody
    5. Whenever the consultant, transfusion medicine/designate requests it.
    6. Whenever the Medinfo HIIG record so indicates (in comment section)
  4. Do the immediate-spin crossmatch if ALL of the following apply:
    1. Only one determination of the ABO/D type
    2. The historical ABO/D type agrees with the current type.
    3. There are no antibodies reacting at 37C AND there is no history of antibodies at 37C.
  5. Use the computer/electronic crossmatch if ALL of the following apply:
    1. There are two determinations of the ABO/D type and they both agree with each other.
    2. The historical ABO/D type agrees with the current type.
    3. There are no antibodies reacting at 37C AND there is no history of antibodies at 37C.
  6. When to do a DAT on a donor unit:
    1. Patient antibody screen is negative but the full AHG crossmatch is incompatible.
    2. Part of a transfusion reaction workup where the AHG crossmatch of donor cells and patient serum is incompatible.
    3. Whenever the consultant, transfusion medicine/designate requests it.
  7. If a donor unit is found with a positive DAT:
    1. Test with polyspecific and monospecific IgG and C3d antisera
    2. Perform an acid-elution.
    3. Send the results to the transfusion medicine consultant/designate for review.
    4. The reviewer will enter his review in HIIG in the Donor Consultation Section both as global donor comment and a result-specific comment against the antibody screen result.
    5. Use of the DAT-positive donor unit:
      1. Select another RBC unit for the transfusion.
      2. The final decision to use the unit will be made by the Transfusion Medicine consultant/designate.

Important:  Don’t do a classic AHG/IAT phase crossmatch unless you have to do it  (see conditions above.)  A donor unit with a DAT is unlikely to be clinically significant and may be transfused safely to the patient in most situations.  Patients receiving electronic-crossmatch and immediate-spin crossmatch are receiving units with positive DAT without incident.

References:

  1. Standards for Blood Banks and Transfusion Services, Current Edition, AABB, Bethesda, MD, USA
  2. Guidelines to the Preparation, Use, and Quality Assurance of Blood Components, European Committee (Partial Agreement) on Blood Transfusion (CD-P-TS), Current Edition
  3. Technical Manual, Current Edition, AABB, Bethesda, MD, USA

Projective Exercise 7

drzeyd

As a transfusion medicine physician, I must know if I can trust my staff’s interpretation of immunohematology testing.  I may be called at night and they will provide me with results and I must use these to make a medical judgment.  If their interpretation is flawed, I might make a decision that harms the patient.

I really don’t like multiple-choice questions, but nowadays this is often the norm.  For my staff, especially senior staff and those who want to be promoted to senior staff, I have developed a series of projective exercises to help me understand their thought processes.

Here is another exercise for ABO discrepancies.  I offered this to senior technologist and supervisory candidates:

Can they name the conditions that give these results?

23/9/20

Projective Exercise 6

drzeyd

Projective Assessment Exercise 6

Zeyd Merenkov, MD, FCAP, FASCP

Independent Consultant in Transfusion Medicine

As a transfusion medicine physician, I must know if I can trust my staff’s interpretation of immunohematology testing.  I may be called at night and they will provide me with results and I must use these to make a medical judgment.  If their interpretation is flawed, I might make a decision that harms the patient.

I really don’t like multiple-choice questions, but nowadays this is often the norm.  For my staff, especially senior staff and those who want to be promoted to senior staff, I have developed a series of projective exercises to help me understand their thought processes.

Here is another exercise using elution:

Will they know to get the medication history?  What are the mechanisms by which a drug may cause a positive DAT?

21/9/20

Processes and Software Building 56: RBC Distribution Rules

drzeyd

In Medinfo HIIG, one sets parameters to determine which antigens must be matched to allow a RBC product to be released.  These criteria may include:

Number of and timing of ABO/D typings

Permissible ABO/D substitutions

Emergency release

Required antigen matches

Optional antigen matches

Exact wording of conditional and blocked combinations

For ABO/D typing, a minimum of two typings must be on record for routine release and the last typing done within 72 hours.  If not, emergency release must be selected.  ABO-incompatible selections must be blocked.  For D-negative patients, only D-typed units may be selected.  D-incompatible transfusions will trigger a message to use D-compatible for females <50 years.

Required antigen typings include using antigen-negative for patients having antibodies against the specified antigen, e.g. D-negative RBCs for patients with active anti-D, c-negative for patients with anti-c, K-negative for anti-K, etc.

Certain antibodies will trigger a message to flag the use of unmatched units but not block the release.

The attached document shows sample settings for RBC release.  Note that these rules are user-definable.

31/10/20