Transfusion Medicine & HLA

Pretransfusion Sample Requirements

EDTA tube, properly labeled, in-date (expires 3 days post-collection), negative Ab screen, ABO/Rh typed.

RBC Transfusion Compatibility: Type O

Can receive only Type O red blood cells.

RBC Transfusion Compatibility: Type A

Can receive Type A and Type O red blood cells.

RBC Transfusion Compatibility: Type B

Can receive Type B and Type O red blood cells.

RBC Transfusion Compatibility: Type AB

Can receive Type AB, A, B, and O red blood cells.

FFP Transfusion Compatibility: Type O

Can receive Type O, A, B, and AB plasma.

FFP Transfusion Compatibility: Type A

Can receive Type A and AB plasma.

FFP Transfusion Compatibility: Type B

Can receive Type B and AB plasma.

FFP Transfusion Compatibility: Type AB

Can receive only Type AB plasma.

Immediate Spin Crossmatch

Mixes patient serum/plasma with donor RBCs at room temperature to detect immediate ABO mismatches.

Electronic Crossmatch

Uses software to verify ABO/Rh compatibility; permitted only if patient lacks unexpected antibodies.

AHG Crossmatch

Incubates at 37°C with AHG serum to detect clinically significant non-ABO IgG alloantibodies.

Antigen Typing Units

Uses commercial antisera to find donor RBCs negative for specific minor antigens (e.g., Kell, Duffy).

ABO Non-Identical RBC Choices: Type AB Recipient

1st choice: Group A; 2nd choice: Group B; final choice: Group O.

ABO Non-Identical RBC Choices: Type A Recipient

Group O red blood cells.

ABO Non-Identical RBC Choices: Type B Recipient

Group O red blood cells.

ABO Non-Identical Plasma Choices

AB plasma is preferred; Group A plasma is the emergency alternative if AB is unavailable.

Neonatal Pretransfusion Testing Requirements

Forward typing only; initial antibody screen uses mother's serum; no serological crossmatch for admission.

Neonatal Red Blood Cell Product Requirements

Must be leukoreduced, irradiated, CMV negative, and Hemoglobin S negative.

Acute Hemolytic Transfusion Reaction

Rapid RBC destruction (usually ABO mismatch) causing fever, flank pain, red urine, and hypotension.

Febrile Non-Hemolytic Reaction

Temp increase ≥1°C from accumulated cytokines or anti-HLA antibodies; lacks hemolysis/respiratory signs.

Allergic / Anaphylactic Transfusion Reaction

IgE response to foreign plasma proteins, or severe IgA-mediated response in IgA-deficient recipients.

TRALI (Transfusion-Related Acute Lung Injury)

Non-cardiogenic pulmonary edema within 6h caused by donor anti-HLA antibodies activating recipient neutrophils.

TACO (Transfusion-Associated Circulatory Overload)

Cardiogenic pulmonary edema within 6h caused by volume overload, leading to hypertension and tachycardia.

Septic / Bacterial Transfusion Reaction

High fever, hypotension, and shock from bacterial contamination; most common in room-temp stored platelets.

Delayed Hemolytic Transfusion Reaction

Anamnestic immune response 2-21 days post-transfusion against non-ABO antigens; causes positive DAT.

Transfusion Reaction Workup Steps

1. Stop transfusion 2. Clerical check 3. Visual plasma check 4. DAT 5. Lab tests 6. Cultures 7. Urinalysis.

Transfusion Transmitted Pathogens

HIV, HBV, HCV, HTLV, West Nile, Zika, CMV, Syphilis, Plasmodium, Babesia, T. cruzi, CJD.

Etiology of HDFN

Maternal IgG antibodies cross the placenta and destroy antigen-positive fetal red cells.

Intrauterine Transfusion Indications & Products

Treats severe fetal anemia; requires O-negative, CMV-negative, leukoreduced, and irradiated RBCs.

Exchange Transfusion Purpose

Removes circulating maternal antibodies, lowers unconjugated bilirubin, and corrects newborn anemia.

Rh Immune Globulin (RhIG) Mechanism

Binds and clears fetal Rh-positive RBCs before maternal immune system recognizes them.

RhIG Vial Dosage Coverage

One 300 µg vial of RhIG covers up to 30 mL of fetal whole blood.

Rosette Test (Fetomaternal Hemorrhage Test)

Qualitative screen to detect fetomaternal hemorrhage in Rh-negative mothers; positive screen requires KB stain.

RhIG Vial Calculation Formula

# of vials = Volume of FMH in mL of whole blood ÷ 30 mL.

HLA Definition & Laboratory Testing Methods

Human Leukocyte Antigen; tested using DNA methods, flow cytometry, or PCR.

HLA Direct Exclusion in Relationship Testing

Child possesses a genetic marker absent in both the mother and the alleged father.

HLA Indirect Exclusion in Relationship Testing

Child lacks a required genetic marker for which the alleged father is homozygous.