Month: Nov 2020

Antigen Typings in the Presence of a Strongly Positive DAT

drzeyd

Principle:

Antigen typing of cells with large amounts of coating antibody (i.e. strongly positive DAT 3-4+) may not always be possible because the bound antibody may block available antigen sites.  This policy is to clarify how to recognize and handle such situations.

Policy:

  1. Always follow the manufacturer’s instructions for the use of the typing reagent.
    1. In particular, note whether a control must be run with the test (e.g. D-control, D-diluent, etc.) or if it is included in the gel or glass bead card.
      1. If a control is required, use exactly what the manufacturer recommends.
      2. DO NOT SUBSTITUTE ANYTHING ELSE AS THE CONTROL!!
  2. Interpret the reactions exactly as the manufacturer indicates.
  3. If the test is invalid because of the control or any other reason, report the antigen typing as indeterminate and send for Transfusion Medicine Physician review.
  4. If the DAT is 3-4+ and the antigen typing shows no reaction (apparent negative), send the case to the Transfusion Medicine Physician for review and final interpretation.  DO NOT ENTER THE RESULT AS NEGATIVE UNLESS THE TMP INSTRUCTS YOU TO DO THIS!!
  5. To rule out a blocking antibody, a special elution to gently remove the coating antibody may be needed so that the RBCs can then be typed (not acid glycine technique—rather, gentle heat elution.)  The Transfusion Medicine Physician will decide whether to do this additional testing.

References:

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

Opinion: Software for Massive Transfusion Protocols–Pools

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Massive transfusion protocols may contain large numbers of different blood components all to be released simultaneously as quickly as possible:

  • Packed RBCs
  • Low-titer group O whole blood
  • Platelets
  • Plasma
  • Cryoprecipitate

For an adult, it might include 6 RBCs, 1 adult platelet dose, 6 plasma, and 10 cryoprecipitate—23 components at one time.

For liver transplant, I had a protocol with 20 RBCs, 3 adult platelet doses, and 20 plasma units—43 components in all.

Even if the blood bank software prints all of these release forms, it requires considerable time to check the identity and serial number of each unit.  This is the rate-limiting step for their release to the critically ill patient.

Our clinicians wanted release within 5 minutes of ordering;  however, it was physically impossible to sign out so many components within this time limit.

Medinfo has facilitated the release by offering pools of one component type (platelets, cryoprecipitate, or plasma).  A pool number is generated to cover the components and this ONE number is used for release.

I would like to see the pooling concept expanded to allow multiple component types to be included in the pool.  Then, at release from the blood bank, only ONE number can be used to sign out the components.

Additionally, the individual units in this mixed pool should be treated the same way as if the units had been released individually including:

  • Apply all protocols for the components.
  • Return individual units back into stock or discard.
  • Use the mixed pool number to view the contents of the pool.
  • Query using the mixed-pool number for its contents.
  • Query the individual unit(s) (e.g. for look-back).
  • Quarantine the unit(s) as needed.

29/11/20

QC of Reagents for Antibody Screening and Identification

drzeyd

Principle:

This policy is a reiteration of current policy to QC reagents used for antibody screening and identification to document how current practice meets these requirements.  This policy is NOT a change from current practice.

Policy:

  1. Each cell used for antibody detection must be checked each day of use for reactivity of at least one antigen using antisera of 1+ or greater avidity:
    1. We will use reactivity encountered during the daily antibody testing:  reactions of 1+ in each screening cell will be deemed acceptable.  For panel cells, reactions of 1+ or greater for any specificity will be deemed acceptable.
  2. Typing reagents such as anti-D, anti-K, anti-Fya, etc. must be checked each day of use.
    1. Already defined explicitly in SOPs
  3. Anti-IgG reactivity of antiglobulin reagents may be checked during antibody screening and crossmatching:
    1. Currently performed as per manufacturer’s instructions (e.g., Immunocor, Biorad, Grifols, Ortho) for gel and tube reagents.
  4. Typing sera and reagent cells must be checked for reactivity and specificity on each day of use, including a check against known positive and negative cells or antisera:
    1. Already defined explicitly in SOPs

Reference:

  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. TRM.31400, CAP Checklist, current version

Assessment of External Technical Qualifications

drzeyd

Principle:

The development of Transfusion Medicine will include recruitment of technical staff with external qualifications, often higher or more advanced than current on-site staff who normally would make their competency assessment.  This policy addresses an interim approach to making a fair, unbiased assessment of these highly qualified staff and avoid conflicts.

Definitions:

External Qualifications:  BB(ASCP), SBB(ASCP), MT(ASCP), MLS(ASCP), RT, ART, AIMLS, FIBLS, or equivalent

Designated Assessor:  Supervisor, SBB, Specialist Physician, or other staff designated by the Head, Transfusion Medicine to perform the assessment

Scope:

This policy applies to all initial (probationary), annual, and all other competency assessments across ALL HMC transfusion services and the Donor Center.

Policy:

  1. Technical Issues:
    1. All staff with external competencies as defined above will have a special assessment for technical skills if there is not a senior staff member with at least the same or higher technical external qualification (e.g. SBB(ASCP), FIBLS, ART for BB(ASCP), RT, or AIMLS).
    2. Senior staff (e.g. SBBs, specialist physicians at outlying hospitals) other than the direct supervisor may perform this technical evaluation if so designated by the Head, Transfusion Medicine.
    3. The supervisor or other designated assessor will liaise with the Head, Transfusion Medicine to develop this assessment for technical skills.
    4. The final arbiter for the content of the assessment will be the Head, Transfusion Medicine.
    5. All such evaluations will be sent by the designated assessor to the Head, Transfusion Medicine for his review and approval.
    6. NO evaluations will be submitted to Laboratory Administration until they have been reviewed, accepted, and signed (with stamp) by the Head, Transfusion Medicine.
  2. Non-Technical Issues:
    1. Non-technical and administrative skills assessment will continue to be conducted by the Supervisor or Specialist Physician of the corresponding transfusion service.  New staff must become proficient in both technical and non-technical issues as described in the job description.
  3. Utilization for Special Procedures:
    1. The Head, Transfusion Medicine reserves the right to utilize such staff for performing special investigations, (e.g. antibodies and other complex immunohematologic testing) even before their full competency assessments and reviews are complete.
      1. In such situations, the Head, Transfusion Medicine assumes full responsibility for such actions.

References:

Standard 1.1.1. and Section 2, Standards for Blood Banks and Transfusion Services, 30th Edition, AABB.

Antibody Titration

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Principle:

The purpose of antibody titration is to determine how to follow a pregnancy at risk for hemolytic disease of the fetus and newborn (HDFN) or for organ transplant (e.g. ABO-incompatible renal or stem cell transplantation).

Titers are notoriously hard to compare across different institutions and different reagents and are subject to variation between technologists. Automated methodologies may help limit this variability.

Policy:

  1. Indications
    1. Pregnant patients with active anti-D to determine if a more aggressive intervention, e.g. percutaneous umbilical blood sampling, is needed to further assess the state of the fetus
    2. ABO-incompatible renal transplantation:  to determine candidacy and follow the effect of ABO column immunoadsorption and immunosuppression
    3. ABO-incompatible stem cell transplantation to follow the course of treatment
    4. External proficiency surveys
  2. Procedure and Interpretation:
    1. Titers may be done in saline or at antiglobulin phase.
    2. Titers may be performed manually or on automated equipment (e.g. Ortho Vision Max).
    3. If the titers are to be used as part of an external protocol, the method should be correlated with the external institution and found to be acceptable.
    4. Titers for organ transplant (e.g. kidney) will be done at saline and antiglobulin phase.
    5. The titer FOR PATIENT REPORTING is defined as the final tube showing a 1+ reaction.
    6. The titer for CAP surveys will be according to the instructions of the CAP, even it does not agree with our 1+ reaction rule.
    7. Any variances from this policy must be specifically approved by a blood bank consultant.

References:

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

Processes and Software Building 56: Multi-Site Patient and Donor Considerations

drzeyd

As our hospital network expanded, there were many patients who moved between locations.  They might first start in an emergency room and then be transferred to a specialty hospital.  These locations might be served from different hospital blood banks/transfusion services.  What happens if work is progress from one site when the new site receives the patient.  Must the previous workup be repeated or could it be used for transfusion at the next site?

For example, the ABO typing could be performed at one site and the antibody screen at a second site, and the antibody identification at still another site.  Could the results be used across the entire system?

I had multiple hospital blood banks and blood donor centers.  The general and specialty laboratories had multiple sites.  The hospital information system was set up so that the various tests could only be performed at specific designated sites.  This posed problems as patients were moved around or if some site(s) became inoperative since the specimens then had to transported at great distances for testing.  Only a few basic STAT tests were available at all sites.

It was my decision to allow all test categories at all sites, e.g. a DAT request from any site, any methodology, could be used to satisfy the order.  Similarly, all donor processes were available at all donor centers (the processes could be completed at one or more sites).  Different hospital blood banks had different equipment but all the test categories were the same across site—the methodologies might differ.  We had at least four different DATs across our system.

The interface between the blood bank and hospital system worked as follows:  In the hospital information system HIS, test orders pointed to a category of testing and any methodology for that category at any site could be used in the blood bank system for testing and reporting back to the HIS.  Any test in a category from any site could be used to satisfy the test request.  Blood bank staff would choose the particular test methodology to use.  It was NOT specified by the HIS!

In summary, for blood banks and donor centers within our system, the work could be flexibly moved between sites.  There was no need to repeat testing when a patient transferred to a new site.  The only type the work was repeated if testing was done at an institution outside our system.

Sample RBC Exchange Form

drzeyd

This form was developed by my senior apheresis staff at HMC Doha in conjunction with me. It organizes the data to minimize the time needed to put the data in place so that the apheresis nurse can concentrate on the patient. It can serve as a good template from which to build a computer form.

I want to thank Ms. Mini Paul, Head Apheresis Nurse, and Dr. Saloua Al Hmissi, Consultant Transfusion Medicine for all their efforts.

ABO Antibodies

drzeyd

Principle:

Historically, the Lui-Freeze-Thaw elution method was used to detect ABO antibodies in suspected cases of ABO hemolytic disease of the fetus/newborn HDFN.  However, the detection of such antibodies does not mean that they are clinically significant.  If a clinically significant antibody is suspected, perform acid elution instead.  If you want to detect ABO antibodies in a neonate or in a transplant setting, you can use this eluate against reagent A and B cells.

Policy:

  1. For suspected cases of significant ABO antibodies (HDFN, organ transplant), perform acid-elution:
    1. For ABO antibodies, test the eluate against reagent A and B cells using antiglobulin phase.
      1. If the mother is ABO-incompatible with the neonate and the neonate’s DAT is positive with a negative eluate against panel cells, then test against A and B cells to rule out ABO antibodies
      2. The same applies to organ transplant cases to detect ABO antibodies.
  2. For detection of non-ABO antibodies, test the eluate against an antibody panel (i.e. group O cells).

References:

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

Training Future Transfusion Medicine Physicians: Need for Technical-Medical Expertise

drzeyd

In a previous post, I discussed transfusion training for hematology fellows and general pathology residents.  I have no expectations that most of them have any interest in the field so I suggested concentrating on the interpretation of the direct antiglobulin test DAT and turn-around-times for services.

In contrast, the transfusion medicine physician in-training needs to understand in detail all processes, donor and patient—especially test interpretation so that he/she can make medical decisions and variances.

During my training, I was fortunate to be in a residency training program that also had an American Specialist-in-Blood Bank SBB training program.  To a large extent, I attended the SBB program and even worked on the “wet” specimens.

I had no delusions that I would ever function as technologist or SBB in the blood bank.  However, that extended blood bank training has made me the physician I am.  I can correlate advanced, even reference, procedures to my medical knowledge and thus provide a unique offering.  In contrast, even the SBB is not a physician and cannot make the medical correlations.  Recently, I was flattered at an AABB meeting when the speaker thought that I was an SBB.

In certain regions where reference immunohematology laboratories and SBBs or equivalent are rare, the transfusion medicine should have sufficient technical background to help fill this gap.  In my practice, I review all antibody and DAT workups and make interpretative comments for the physicians and nursing staff.  These comments are entered into the blood bank computer system.

I personally tutor the trainees and make certain that they understand potentially dangerous patterns such as antibodies to high-incidence antigens, significance of the autocontrol in panreactivity, and assessing for fatal acute transfusion reactions—both hemolytic and non-hemolytic.

It also helps when I can discuss with my technical staff my interpretations and choices for clinical management.  They get a better idea how important their work is for patient care and understand how any errors may adversely affect the patient.

In regions where there are good immunohematology reference laboratories, some of this may be less necessary.  I lament that transfusion medicine physicians may not maintain these skills and must rely on others to their detriment.  Even if one is comfortable with this, the physician is still ultimately responsible for making the clinical decision.

ABO Subgroup Testing for Organ Donors

drzeyd

Principle:

Organ donors with a history of RBC transfusion within the past three months must have ABO subgroup (weak A as detected by A2 cells and anti-A1 lectin) if the transfusion included group A RBCs.

Policy:

  1. Organ donors who are typed as A should be tested to distinguish group A1 from weak subgroups of A.
  2. Use anti-A1 lectin and A2 cells as indicated.

Reference:

Standards for Blood Banks and Transfusion Services, AABB, Current Edition, Bethesda, MD, USA