Immunohematology and Serological Crossmatching Vocabulary

Vocabulary practice flashcards covering serological crossmatching, typing controls, reagent protocols, and sources of laboratory error.

Serological Crossmatch

A compatibility procedure testing patient plasma (antibodies) against donor red cells (antigens), required for new patients or those with a current/past positive antibody screen or DAT.

Coombs Crossmatch

A crossmatch method carried out through the AHG phase, performed when a patient has a active or historical alloantibody, a positive DAT, or recent RhoGAM administration.

Immediate Spin Crossmatch

A quick compatibility test performed by centrifuging patient plasma and donor cells immediately to confirm ABO compatibility when the antibody screen is negative and no historical antibodies exist.

Passive Anti-D

A temporary anti-D antibody result detected in patient plasma following an injection of RhoGAM rather than an immune response to transfused red blood cells.

RhoGAM Reaction Profile

A weak positive anti-D reaction giving typical agglutination of $1+$ to $2+$ and a titer around $8$, which gradually disappears within $10$ to $14$ weeks post-injection.

True Anti-D Reaction Profile

An immune anti-D reaction characterized by strong $3+$ to $4+$ agglutination reactions and an antibody titer of $64$ or higher.

Electronic Crossmatch

A computer-based selection process used when a patient's antibody screen is negative and passive antibodies have cleared, provided two concordant ABO/D blood types are on record.

Heterozygous Positive Control

A control cell possessing a single dose of a target antigen (expressing two different allele antigens), used in quality control to verify detection of the weakest acceptable reaction.

Homozygous Antigen Expression

An antigen expression pattern on a red cell featuring a double dose of a single antigen without its allele counterpart (positive for one allele antigen, negative for the other).

Kidd Antibodies

Antibodies known for fading rapidly in storage and testing but quickly reappearing upon re-exposure, making them a leading cause of delayed transfusion reactions.

Rare Antiserums

Reagents for uncommonly found antigens (such as anti-KPa or anti-JSa) that may be frozen and used past their expiration date if quality control testing passes.

False Negative from Heavy Cell Suspension

An erroneous negative reading in crossmatching or antigen typing caused by an excessively dense cell concentration that masks visible agglutination.

False Negative from Improper Washing

A failure to observe agglutination caused by inadequate tube washing, leaving unbound plasma proteins that neutralize the added AHG reagent.

False Positive from Oversentrifugation

An artifactual positive result caused by centrifuging tubes for too long or at too high a speed, packing red cells into a button that cannot be gently resuspended.

False Positive from IV Fluid Contamination

An erroneous agglutination result occurring when a blood specimen is drawn near or contaminated by intravenous fluids, particularly glucose or Ringer's lactate.

Wharton's Jelly

A gel-like substance present in umbilical cord blood specimens that can cause spontaneous, false positive agglutination if red cells are not thoroughly washed.

Mechanical Cell Washers

Automated laboratory instruments requiring routine decontamination with Clorox, followed by deionized water and saline washes, to eliminate bacterial and fungal growth.

Check Cells

IgG-sensitized red cells added to every negative AHG tube test to confirm that functional AHG was added and was not neutralized by leftover plasma proteins.

EDTA Tube

A purple-top blood collection tube that deactivates complement, stabilizing specimens and preventing complement-mediated false test reactions over time.

Manufacturer's Package Insert

The instruction sheet provided with antisera that specifies exact incubation times, temperatures, and requirements for centrifuging or potentiators during antigen typing.

PEG (Polyethylene Glycol)

A potentiator reagent requiring $10$ to $15$ minutes of incubation that must NOT be centrifuged following the $37^\text{o}\text{C}$ incubation phase.

LISS (Low Ionic Strength Solution)

An enhancement medium added to crossmatches that requires centrifugation and macroscopic reading after $37^\text{o}\text{C}$ incubation prior to the wash phase.

Switchboard Identity Verification

A safety procedure where a blood bank tech calls an outside facility back through its official switchboard number to verify identity before releasing patient history.

M and N Allele Pair

Blood group system antigens that function as partner alleles, where a cell expressing both M and N is heterozygous and a cell expressing only one is homozygous.

3% Red Cell Suspension

The standard concentration of donor red blood cells diluted in saline used for crossmatch procedures and antigen typing.