Blood Banking Techniques and HDFN (ASCPi)

Antibody identification panel

It is used to determine specificity when an antibody is detected

Unbound antibodies

Tubes are washed with saline to remove:

ABO interference

Group O donor cells are used to prevent:

Antigen profile sheet

Lot-specific and essential for interpretation

Incubation time and reaction strength

Choice of reagent affects:

Monospecific anti-IgG

Which AHG reagent is preferred for antibody screening?

Polyspecific

Which AHG reagent may detect clinically insignificant complement-binding IgM?

Alloantibody

A positive screen and a negative autologous control would likely indicate:

Possible autoantibody or drug-induced

A positive autologous control would likely indicate:

Rouleaux

“Stacked coin” formation; seen in all serum-containing tests; doesn’t interfere with AHG phase

• Review of patient history.

• Antibody identification panel testing.

• Autocontrol or Direct Antiglobulin Test (DAT) if not done prior.

• Consistent methods/phases with those used in the antibody screen.

Antibody identification requires:

Donor RBCs still circulate

After transfusion, mixed-field reactions occur during phenotyping when:

EGA method

Which treatment method uses EDTA & glycine-HCl, and denatures Kell antigens

Chloroquine diphosphate method:

Which treatment method preserves Kell antigens and longer incubation?

Selected Cell Panels

Helps differentiate between antibodies when multiple are suspected

• Narrowing down specificities.

• Enhancing or destroying antibody reactivity

Proteolytic enzymes are useful for:

Adsorption

It is used to remove antibodies from serum in order to detect others that may be masked

Rabbit erythrocyte stroma

It is a commercial adsorption product which removes cold autoantibodies (anti-I, anti-H, anti-IH).

3 months

In autoadsorption, patient’s RBCs must not be transfused in the last:

Elution

Used after a positive IgG DAT to identify antibodies on RBCs.

Non-reactive

During elution, the last wash should be:

Lui Freeze-Thaw Method

During elution, which method involves freezing at –18°C or colder?

Heat Method

During elution, which method involves incubation at 56°C?

ABO antibodies

Temperature-dependent elution is best used for:

pH method (Acid Elution)

Which elution method uses glycine acid to disrupt antigen-antibody bonds?

Non-ABO IgG

pH Method (Acid Elution) is best used for:

RBC membrane lipids and van der Waals forces

Organic solvent elution disrupts:

Due to toxicity and time requirements

Why is organic solvent elution rarely used?

Antibody titration

Quantifies antibody concentration via two-fold serial dilution.

• ≥ 4-fold titer increase

• Score increase ≥ 10

Antibody titration is considered clinically significant if:

Most to least diluted

One should read antibody titration results from:

• Monitors pregnancy risk of HDFN

• Differentiate immune anti-D vs RhIg

• Detect HTLA antibodies

Applications of Antibody Titration:

Major Crossmatching

It consists of mixing the RECIPIENT’S SERUM and DONOR’S RED CELL

Minor Crossmatching

It consists of mixing the DONOR’S SERUM and RECIPIENT’S RED CELL

Broad spectrum crossmatching

It is the most preferred type of crossmatching

Tube method

It is the gold standard of technologies in blood banking

Dextran acrylamide gel

Gel technology uses a plastic microtube containing:

• STANDARDIZATION

• Stability

• Decrease sample volume needed for testing

• Enhanced sensitivity and specificity

Advantages of Gel testing:

Solid phase technology

In this technology, the test reactant is bound to solid support (microtiter wells) before test is started

Affinity column technology

This technology has the principle of affinity adherence of IgG sensitized RBCs to an immunologically active matrix

Levine, Stetson

They reported a transfusion reaction from transfusing a husband’s blood to a postpartum woman; postulated that the mother had been immunized to the father’s antigen through fetomaternal hemorrhage

• Antigenic Exposure

• Host Factors

• Immunoglobulin Class

• Antibody Specificity

• Influence of Blood Group

Factors that affect immunization and severity of HDFN:

1

As little as ___ mL can immunize the mother

IgG1 and IgG3

Which immunoglobulins are more efficient in RBC hemolysis than IgG2 and IgG4?

D

It is the most immunogenic antigen

Anti-Kell

It is considered the most clinically significant antibody due to its ability to cause HDFN

Decreased

When mother is ABO incompatible with fetus, fetomaternal hemorrhage is:

Erythroblastosis fetalis

Term used to describe the stimulation of fetal bone marrow to produce RBCs at an accelerated rate due to destruction of fetal RBCs

Hydrops fetalis

Term used to describe the development of high-output cardiac failure with generalized edema, effusions, and ascites caused by severe anemia and hypoproteinemia

Father’s blood

In the context of HDFN, whose blood should be tested for the presence and zygosity of the corresponding antigen?

Second trimester

When can maternal plasma be tested for fetal DNA to determine genotype?

Red

Color Doppler indicates the direction of blood flow using which color for arterial flow?

Blue

Color Doppler indicates the direction of blood flow using which color for venous flow?

Cordocentesis

Procedure used to obtain a sample of fetal blood

Amniocentesis

For management of HDFN; used to estimate the extent of fetal hemolysis

10-12 weeks

Amniocentesis can be done as early as:

Liley graph (according to gestational age)

Amniocentesis measurement is plotted on:

Zone I

Which zone in the Liley graph predicts mild or no disease, and does not require intervention?

Zone II

In this zone in the Liley graph, most fetuses have moderate diseases that may require intervention

Zone III

This zone in the Liley graph indicates severe & often life-threatening; hemolysis & require urgent intervention

• MCA-PSV indicates anemia

• Fetal hydrops is noted on ultrasound examination

• Cordocentesis blood sample has hemoglobin level less than 10 g/dL

• Amniotic fluid AOD 450 nm results are high

Intrauterine transfusion is necessary when one or more of these conditions exist:

To maintain fetal hemoglobin above 10 g/dL

The goal of intrauterine transfusion is:

70%

During intrauterine transfusion, the hematocrit level of the RBCs to be transfused should be greater than:

Phototherapy

This method of managing HDFN is used to change the unconjugated bilirubin to isomers, which are less lipophilic and less toxic to the brain (460-490 nm)

Intravenous Immune Globulin (IVIG)

It is used to treat hyperbilirubinemia of the newborn caused by HDFN

Exchange Transfusion

Which method of managing HDFN prevents kernicterus?

Anemia and requires transfusion

In exchange transfusion, hemoglobin levels below 10 g/dL indicates:

Severe anemia

In exchange transfusion, hemoglobin levels below 7 g/dL indicates:

14-20 g/dL

Full-term newborn infants have a normal hemoglobin range of:

Serologic testing

It is used to confirm HDFN and prepare for possible transfusion

DAT

It is the most important serologic test for diagnosing HDFN

Less than 7 days from collection

For newborn transfusions, blood units should be:

Within 72 hours after birth

An Rh-negative nonimmunized mother should receive RhIG soon after delivery of an Rh-positive infant:

U.S regular dose vial (300 ug)

It protects against 15 ml of packed RBCs or 30 mL of whole blood

Kleihauer-Betke test

Used to quantitate actual amount of fetomaternal hemorrhage; maternal blood smear is treated w/ acid or alkali and counterstain