ASCP BB flashcards

32 cards. Read the term and the definition here. The deck at the top of this page is optional.

ABO gene location

The ABO gene is located on chromosome 9, while the H gene (FUT1) is on chromosome 19 and determines H antigen expression.

IgG antibody characteristics

IgG antibodies are monomeric, cross the placenta, react optimally at 37°C, and are detected by indirect antiglobulin testing; they cause delayed hemolytic reactions.

Duffy antigen receptor

The Duffy antigen Fy6 is a receptor for Plasmodium vivax; people with Fy(a-b-) phenotype are resistant to vivax malaria and commonly have West African ancestry.

Kidd antibody behavior

Anti-Jka and anti-Jkb often show dosage, can become undetectable over time, and cause delayed hemolytic transfusion reactions with a positive DAT.

Autocontrol interpretation

A positive autocontrol with panreactive panel cells suggests an autoantibody; allogeneic adsorption may reveal an underlying clinically significant alloantibody.

Enzyme treatment effects

Ficin or papain enhances Rh, Kidd, Lewis, and P1 antigens but denatures Duffy, MNS, and Xga antigens, helping antibody identification.

DTT treatment effect

Dithiothreitol denatures Kell, Lutheran, and Dombrock antigens while preserving many other antigens, so it can distinguish these specificities.

Antibody titration endpoint

The titer is the reciprocal of the highest serum dilution showing visible reactivity; a higher titer indicates greater antibody concentration.

Electronic crossmatch criteria

Electronic crossmatch requires two concordant ABO/Rh typings, no history of clinically significant antibodies, a negative antibody screen, and a validated computer system.

Immediate-spin crossmatch

Immediate-spin crossmatch at room temperature primarily detects ABO incompatibility; it does not reliably detect IgG antibodies reactive at 37°C.

Pretransfusion sample validity

A pretransfusion sample is generally valid for 3 days if the patient was transfused or pregnant within the prior 3 months; policy may extend it.

Universal RBC donor

Group O negative RBCs are the universal RBC donor because they lack A, B, and D antigens; group AB plasma is the universal plasma donor.

Platelet storage conditions

Platelets are stored at 20-24°C with continuous agitation for up to 5 days, and the pH must remain at least 6.2 at expiration.

RBC storage temperature

RBC units are stored at 1-6°C; additive-solution units may be stored up to 42 days, while CPDA-1 units are stored up to 35 days.

Irradiation dose

Cellular blood components are irradiated with 25 Gy (2500 cGy) to the midplane to prevent transfusion-associated graft-versus-host disease.

Leukoreduction threshold

Leukoreduction reduces residual white cells to less than 5 x 10^6 per unit, lowering febrile nonhemolytic reactions and cytomegalovirus transmission risk.

Acute hemolytic reaction signs

Acute hemolytic transfusion reaction presents with fever, chills, flank pain, hypotension, and hemoglobinuria; the transfusion must be stopped immediately.

TACO features

Transfusion-associated circulatory overload causes dyspnea, hypertension, and pulmonary edema within 6 hours; treatment includes oxygen and diuretics.

TRALI features

Transfusion-related acute lung injury causes hypoxemia and bilateral infiltrates within 6 hours without volume overload; donor antibodies are often implicated.

Delayed hemolytic reaction

Delayed hemolytic transfusion reaction occurs 3-14 days after transfusion with falling hemoglobin, positive DAT, and a new alloantibody.

RhIG 300 microgram dose

A 300-microgram dose of Rh immune globulin neutralizes about 15 mL of fetal RBCs or 30 mL of fetal whole blood.

Kleihauer-Betke test

The Kleihauer-Betke test detects fetal hemoglobin resistant to acid elution and quantifies fetal-maternal hemorrhage to guide RhIG dosing.

MCA-PSV anemia threshold

A fetal middle cerebral artery peak systolic velocity greater than 1.5 multiples of the median suggests moderate to severe fetal anemia.

ABO HDFN features

ABO hemolytic disease of the newborn is usually mild, occurs in group O mothers with IgG anti-A or anti-B, and commonly affects A or B infants.

Donor hemoglobin criteria

Donor hemoglobin must be at least 12.5 g/dL for women and 13.0 g/dL for men, with a hematocrit of at least 38%.

NAT window periods

Nucleic acid testing shortens infectious window periods to about 9-11 days for HIV, 3-7 days for HCV, and 20-25 days for HBV.

Malaria travel deferral

A donor who traveled to a malaria-endemic area is deferred for 12 months unless specific exemption criteria are met.

Confirmed positive donor test

A confirmed positive infectious disease test requires donor deferral, discard of the unit, and notification or lookback as required.

Proficiency testing requirement

Proficiency testing is required for ABO/Rh typing, antibody detection, crossmatch, and infectious disease testing to monitor laboratory performance.

Competency assessment timing

Laboratory personnel must have competency assessed before performing patient testing and at least annually thereafter, with records retained.

CAPA meaning

Corrective and preventive action addresses root cause, prevents recurrence, and documents effectiveness after a nonconformance or error.

Computer crossmatch validation

A computer crossmatch system must be validated before use and must require two ABO typings, a negative screen, and no antibody history.