Pre-transfusion testing - Blood Banking

What mist be retained as part of the transfused patient's permanent medical record?

A statement of compatibility

Recipient serum/ plasma must be tested for clinically significant antibodies:

Abs that react at 37C or AHG, known to have caused transfusion reaction or known to reduce the survival of RBCs post-transfusion

Preoperative Autologous Blood

* Pretransfusion testing and identification of the recipient and the blood sample are required and must conform to the protocols - Tests for unexpected antibodies in the recipient sample and a crossmatch test are optional. - These units must be labeled "For autologous use only."

Neonatal Transfusions:

*Blood for an exchange or regular transfusion of a neonate (younger than 4 months of age) *ABO and Rh testing required - Blood type of infant used unless ABORh is involved with feto-maternal incompatibility - ABO front typing completed on pre-transfusion infant sample * Antibody detection testing required - Performed on maternal sample or eluate from fetal sample *Blood should be as fresh as possible, not older than 7 days. - Group O cells should only be used - CMV- units

Limitations of Compatibility Testing Procedures

*No current testing procedure can guarantee the fate of a unit of blood that is transfused. - Even a compatible crossmatch cannot guarantee that the transfused RBCs will survive normally in the recipient. - May help maintain a patient long enough until production of RBCs on their own

Massive transfusions should use:

*Use antigen negative units for patient with known antibodies if possible. - antibody may not present itself due to dilution of blood products - rapid rise in titer or destruction of donor cells may happen due to antigen positive cells

What is required at the collecting facility?

- ABO grouping and Rh typing (including a test for weak D) and tests intended to prevent disease transmission must be performed. - Required screening for unexpected antibodies - Required standards for reagents used in testing

If an alloAb in the Pt's serum reacting with the corresponding Ag on donor RBCs:

- Auto control tube negative while other cells tested are positive - High incidence or multiple antibodies if all donors are incompatible - Low incidence if antibody screen is negative and only one unit is incompatible - Passively acquired ABO agglutinins after transfusion of non-ABO specific blood

If prior coating of the donor RBCs with protein, resulting in a positive antihuman globulin test:

- DAT performed on donor cells-if one isolated positive result is obtained - Will be incompatible with all recipient serum in AHG phase

Antiglobulin Crossmatch

- IS crossmatch procedure that includes incubation at 37C and AHG phases of testing - Enhancements used to boost antigen-antibody reactions - Used in patients with history or reacting alloantibodies - Auto control can be used in parallel to validate crossmatch results (no longer required)

If abnormalities in the pt's serum are present:

- Imbalance of albumin and gamma globulin (rouleaux) - Saline replacement procedures may help solve issues

Causes of positive results in the serologic crossmatch:

- Inccorect ABO grouping of the pt or donor - An alloAb in the Pt's serum reacting with the corresponding Ag on donor RBCs - An autoAb in the pt's serum reacting with the corresponding Ag on donor RBCs - Prior coating of the donor RBCs with protein, resulting in a positive antihuman globulin test - Abnormalities in the pt's serum - Contaminants in the test system

If a patient requires a transfusion of RBC components before pre-transfusion testing is complete:

- Must proceed by an established protocol. - Adequate pre-transfusion samples necessary. - Patient's ABO and Rh group should be determined. - Accurate records must be kept. - Patient's physician must authorize.

Steps in pre-transfusion testing

1. request 2. ID of transfusion recipient and blood specimen collected 3. testing of transfusion recipient's blood specimen - acceptability and ABORh/history 4. Donor ABORh/RBC testing 5. Donor RBC unit selection - compatible with pt in regards of ABORh and unexpected Abs 6. Compatibility testing (Serologic, computer, or electronic) 7. Labeling of blood with recipient's ID

Computer crossmatch:

The computer crossmatch compares recent ABO serologic results and interpretations on file for both the donor and the recipient being matched and determines compatibility based on this comparison

What is done when units are alloantibody positive and other antibodies have been ruled out?

Unit is antigen typed

Before transfusion is initiated:

a reliable professional (and preferably two professionals) must once again verify identity of the patient and donor products.

Transfused RBCs should have:

acceptable survival rate and there should not be significant destruction of the recipient's own RBCS

Neonatal transfusions should be compatible with what?

any maternal antibodies that have entered the infant's circulation and are reactive at 37°C or AHG

Most critical step in prevention of mis-transfusion:

bedside check prior to blood administration

First choice for transfusion:

blood and components of the patient's own ABO and Rh

A major cause of transfusion-associated fatalities is:

clerical error resulting in incorrect ABO groupings and transfusion of ABO incompatible blood

What do you look for in the visual inspection of donor units?

hemolysis? - pink color, increased potassium and hemoglobin correct labeling? color? turbidity? clots? leakage?

If reactions take place below 37C:

no need to provide Ag neg units

Crossmatch testing:

testing the patient's serum with donor RBCs It is a final check of ABO compatibility between donor and patient. It may detect an antibody in the patient's serum that will react with low frequency antigens

When donor units of an ABO group other than the recipient's own type have been transfused:

testing the recipient's serum in a freshly drawn sample for the presence of unexpected anti-A and/or anti-B must be performed prior to giving any additional RBC transfusions

Samples for donor testing must be collected at the same time as:

the full donor unit

RBCs for the donor pre-transfustion testing can be prepared from what?

the segmented tubing through which the donor blood was collected

The primary objective of the crossmatch test is:

to detect the presence of Abs in the recipient's serum (includes anti-A and anti-B, that could destroy transfused RBCs)

Whatever system is used, the information should be:

verified at least twice before the transfusion of the blood product

What about patients transfused or pregnant within the past 3 months?

New sample must be obtained within 3 days of transfusion or procedure If patient has not been transfused- Specimen may be collected up to 21 days before procedure.

If ABO group-specific blood is not available or is in less than adequate supply:

O neg and O pos blood is recommenced AB plasma can be given to anyone O pts can receive any plasma A pts can receive A or AB plasma B can receive B or AB plasma AB can only recieve AB plasma

For all untested units of transfusion:

Physician must sign a waiver of testing or a release form Rationale- Better to give the patient a chance to survive now and treat the immune-mediated anemia later

What are the advantages and disadvantages of using plasma?

Plasma may contain small fibrin clots, indistinguishable from agglut. Anticoagulants may inactivate complement components Easier to handle than serum samples

Compatibility testing procedures are not required for the transfusion of what?

Plasma products - IS sufficient to detect ABO incompatibility

Intrauterine transfusions are done using: Why?

Mother's serum - babies do not have the Abs in their serum

Before blood is taken from the blood bank to the patient treatment area, check:

ABO and Rh results Clinically significant unexpected antibodies Adverse reactions to transfusion

Immediate spin phase is used to confirm what?

ABO compatibility

If incorrect ABO grouping of the Pt or donor:

ABO typing should be immediately repeated Observed as a strong 4+ reaction at IS

Usual Abs seen are:

ABO, Rh, Kidd, Duffy, S, s, U, P and Kell

If an autoAb in the pt's serum reacting with the corresponding Ag on donor RBCs:

Auto-control tube will be positive and tests of patient serum with donor cells will be positive

Intrauterine Transfusions

Blood for intrauterine transfusion must be compatible with maternal antibodies capable of crossing the placenta

Patient RBCs can be obtained from what?

Clotted or anticogagulated samples

What is required at the transfusing facility?

Confirmation testing ABO group testing and Rh typing - weak D not required

Immediate Spin Crossmatch (aka abbreviated crossmatch)

Consists of ABORh/AS/ IS XM Used when no unexpected alloantibodies are discovered Mix 2 drops patient serum/ plasma with 1 drop donor cell suspension - centrifuge for 30 sec and read for agglutination

Possible test contaminants:

Dirty glassware, bacterial contamination of specimens or saline, fibrin clots, etc.

How do you confirmation of information on the sample and requisition form within the blood bank?

Manually and visually check the patient tube with the patient requisition form/ worksheet/ etc.

What must be checked in intrauterine transfusions?

Maternal Abs to donor Ags Donor unit must lack antigens to any identified maternal antibodies Ensure there is no feto-maternal ABO or Rh incompatibility

Most common cause of error:

Misidentification of the recipient

What must be recorded when testing pt samples?

Results of ABO, Rh, and unexpected antibody screening and unusual serologic reactions and the ID of unexpected Abs in pt's serum

What specimen type is used for pre-transfusion testing?

Serum or plasma

Test performed, advantages and the limitations of a Type test scheme?

TP: ABO, Rh A: Specimen collected, Pt type known L: AS not performed

Test performed, advantages and the limitations of a Type and Screen test scheme?

TP: ABO, Rh, AS A: Most of pre-transfusion testing performed, compatible units can be provided L: Does not include XM

Test performed, advantages and the limitations of a Type/Screen/XM test scheme?

TP: ABO, Rh, AS, and XM A: routine pre-transfusion testing along with XM performed L: units removed from inventory and may not be available for use by other pts

Test performed, advantages and the limitations of a Hold Tube test scheme?

TP: None A: Specimen collected L: testing not performed

Test performed, advantages and the limitations of a No Order test scheme?

TP: none A: none Limitations: no specimen collected, not testing performed

Blood Inventory Management

The Maximum Surgical Blood Ordering Schedule (MSBOS) was developed to promote more efficient utilization of blood and to establish realistic blood ordering levels for certain procedures. - Utilization of a Type and Screen policy, along with MSBOS, may enhance the effectiveness of the blood inventory management program.

Massive Transfusion:

The administration of 8 to 10 RBC units to an adult patient in less than 24 hours OR the acute administration of 4 to 5 RBC units in 1 hour (AABB Technical Manual).