Tag: Immunohematology

Immunohematology testing and processes

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

CMV Prophylaxis Policy

drzeyd

I developed this policy for HMC Doha where most of the local population are CMV-seropositive. Note that I used the CE definition of <1E6 instead of the American <5E6.

Principle:

Since most of the local population (>90%) are CMV-seropositive, it is impractical to rely on CMV-negative donors as our basis for CMV prophylaxis.  Instead, we perform universal leukodepletion and pathogen-inactivation to greatly reduce this risk:

  1. CMV transmission risk can be lowered to a level comparable to using CMV-seronegative components by universal leukodepletion to levels <1E6.
  2. Pathogen inactivation greatly reduces (at least 2 log10) the number of organisms with nucleic acid (DNA or RNA) and is used for all platelet (pools and apheresis) and plasma components.
  3. Platelet additive solution reduces the amount of original plasma to about 35 ml and further reduces donor exposure to foreign material.

Policy:

  1. All blood components (platelets, plasma, RBCs) are universally leukodepleted to residual levels below 1E6.
  2. All platelet and plasma components are pathogen-inactivated using the Mirasol system (riboflavin added and then exposed to ultraviolet light).
  3. All platelet components (pooled buffy coat and apheresis) are prepared in platelet additive solution PAS.

References:

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

Processes and Software Building 46: Reconstituted Whole Blood

drzeyd

Exchange transfusions using reconstituted whole blood were much more common in the past.  Much of the time IVIG now takes care of hemolytic disease of the fetus/newborn HDFN.

In Medinfo, we took a fresh (<= 14 day old) packed RBC in SAGM, group O, Rh-compatible and mixed it with a unit of group AB plasma—the desired hematocrit could be achieved by adjusting the amount thawed plasma that we added.  The product could then be aliquoted and irradiated.  Note that I medically chose to use either FP24 or FFP.

Here is the Medinfo process:

19/9/20

Selection of Components for ABO-Incompatible Renal Transplants

drzeyd

Principle:

Kidneys have strong expression of ABO type and must be matched the same way as RBC components.  In the case of ABO-incompatible renal transplants, we must not give significant amounts of plasma incompatible to the ABO type of the donor kidney.  Plasma must also be compatible with the patient’s ABO type for RBC transfusions.  The amount of residual plasma in PRBCs is limited since we use an additive solution SAGM.  Likewise, platelet components are suspended in platelet additive solution with only minimal residual plasma.  Cryoprecipitate has only minimal plasma and is given without regard to the patient’s ABO type.

Policy:

  1. RBC components:  Use ABO-compatible RBCs in SAGM.  DO NOT USE WHOLE BLOOD!!
  2. Platelet components in platelet additive solution PAS (normally available component):  Any ABO type may be given
  3. Platelet components in plasma:  Only group AB platelets may be used.
  4. Plasma (any type FFP, FP24, solvent-detergent treated, or thawed):  Only group AB plasma may be used
  5. Cryoprecipitate:  Any ABO type including mixed types may be used, mixed types are preferable to neutralize the minimal ABO-incompatible plasma.

References:

  1. Standards for Blood Banks and Transfusion Services, AABB, Current Edition, Bethesda, MD USA
  2. Technical Manual, AABB, Current Edition, Bethesda, MD, USA

Policy: ABO-Incompatible Plasma for Infants

drzeyd

Principle:

HMC Blood Donor Center used platelets (buffy coat pools) and/or apheresis-derived suspended in PAS (platelet additive solution).  In each platelet pool or apheresis platelet, less than 35 ml (average < 20%) of the original plasma. This was much less than would remain if volume-reduced platelets had been prepared by centrifugation. Furthermore, the platelets would NOT be traumatized by the centrifugation.

Policy:

  1. For neonates (< 4 months old) and infants (<20 kg), we will give preference to use plasma-compatible platelet and plasma type.
  2. In any case, PAS-suspended platelets will be used with little residual plasma (far less than if we had centrifuged them).
  3. In the rare event that plasma-compatible platelet types are not available, the transfusion medicine physician must approve the release.

References:

  1. Standards for Blood Banks and Transfusion Services, Current Edition, AABB, Bethesda, MD, USA
  2. Guide to the Preparation, Use, and Quality Assurance of Blood Components, European Committee (Partial Agreement) on Blood Transfusion, Council of Europe, Strasbourg, France

External Disaster Plan

drzeyd

Principle:

Maintaining an adequate blood supply and expedited compatibility testing are critical in disaster planning.  This plan is assuming that the Blood Donor Center is functional and can process donors and make components.

Medinfo Hematos IIG System is critical to monitoring inventory, preparing blood components expeditiously using Good Manufacturing Processes, and distributing blood components in a timely controlled manner.

Policy:

  1. Determinate total available blood supply across all locations by using the Cumulative Stock Display program in Medinfo Hematos IIG.
    1. Recheck stock at least every hour during the disaster.
  2. At each transfusion service site, in conjunction with the Transfusion Medicine Consultant:
    1. Cancel reservations for elective surgical and non-emergency medical cases of affected ABO/D types.
    2. Retain reservations for antigen-matched, oncology, NICU, and high-risk obstetrical cases.
  3. Inform Manager for Donor Recruitment/Logistics to send SMS, radio, and television messages for blood donors—all types.
  4. Contact ALL staff and have them report to duty.
    1. At Blood Donor Center, the Head Nurse, Recruitment Manager, Supervisor, Component Processing, and Supervisor, Marker Testing will contact their respective staff.
    2. At various hospital blood bank transfusion services, the site supervisor will contact all staff.
  5. Process blood components using automated component technology (Reveos).
  6. Perform all donor marker testing including single-well NAT.
    1. Abbreviation of donor testing is only at the discretion of the Head, Transfusion Medicine.
  7. Send blood components using Inter-Depot Transfer function of Medinfo.
  8. Transfusion Services:
    1. Release blood component according to the various protocols as needed:
      1. Massive transfusion protocol
      2. Emergency release
      3. STAT
      4. Priority
      5. Routine
  9. Compatibility testing will be electronic, immediate-spin, or full AHG as per our protocols.

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

Revised 10/9/20

Projective Exercise 6: ABO Discrepancies

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 series of exercises, usually given to advanced technologists and supervisor candidates.  I want them to tell me what they need to assess each scenario.  Can they definitively diagnose solely on the information provided?

These are open-ended and may have more than one possible interpretation:

9/9/20