ABPath Combined AP/CP Primary Certification key terms

Naturally occurring IgM antibodies against the A or B carbohydrate antigen a person lacks, produced after environmental exposure to similar antigens; they fix complement and cause immediate intravascular hemolysis if ABO-incompatible blood is transfused.

A method that detects IgG antibodies in serum by incubating serum with reagent red cells, washing away unbound globulin, then adding anti-human globulin to bridge antibody-coated cells into visible agglutination; it underlies the antibody screen and crossmatch.

Anti-human globulin is added directly to washed patient red cells to detect antibody or complement already bound to their surface in vivo; used to evaluate hemolytic transfusion reactions and autoimmune hemolysis.

A technique that removes unwanted antibodies from serum by incubating it with red cells carrying the corresponding antigen. Autoadsorption uses the patient's own cells to unmask alloantibodies in autoimmune hemolysis; alloadsorption uses donor cells when autoantibody is too strong.

An anamnestic antibody response occurring days to weeks after transfusion, usually against Rh, Kell, or Kidd antigens, producing a falling hematocrit, a positive DAT, and a newly detectable alloantibody on the antibody screen.

New hypoxemia with bilateral pulmonary infiltrates within 6 hours of transfusion, without circulatory overload, often from donor antibodies reacting with recipient leukocytes. It is a leading cause of transfusion-related death.

Proactive treatment of blood components, such as psoralen with ultraviolet light or solvent-detergent, that inactivates residual bacteria, viruses, and parasites, adding a safety layer beyond donor screening and serologic testing.

An organized system delivering red cells, plasma, and platelets rapidly and in balanced ratios to patients with severe hemorrhage, aiming to prevent dilutional coagulopathy, hypothermia, and acidosis while minimizing delay.

The central 95% of values from a defined healthy reference population, usually estimated from at least 120 individuals; it describes typical values rather than a boundary between health and disease.

Falsely low or normal results in a sandwich immunoassay when extremely high analyte concentrations saturate both capture and detection antibodies, preventing sandwich formation; suspected when a result conflicts with the clinical picture.

Sodium minus chloride minus bicarbonate, approximating unmeasured anions; combined with the delta ratio it helps classify metabolic acidosis and screen for lactate, ketones, uremia, or toxins.

The kappa-to-lambda ratio of unbound light chains measured by immunoassay; abnormal ratios and absolute values indicate clonal plasma cell or B cell disorders, including light chain myeloma and AL amyloidosis.

A screening test in which patient serum is applied to HEp-2 cells and fluorescent conjugate reveals antibodies binding nuclear antigens; titer and pattern guide, but do not confirm, a diagnosis of systemic autoimmune disease.

Assays measuring cardiac troponin at concentrations found in healthy people, interpreted against sex-specific 99th percentile upper reference limits and serial change criteria to diagnose or exclude acute myocardial infarction.

Comparison of a new result with the same patient's previous value within a defined interval; a change exceeding the threshold prompts review for specimen mislabeling, collection error, or genuine clinical change.

The aspirate gives cellular detail and differential counts, while the core biopsy shows cellularity, architecture, and fibrosis; both, with touch imprints and flow cytometry, are usually needed to diagnose marrow neoplasms.

Measurement of surface and intracellular antigens on individual cells labeled with fluorescent antibodies, used to assign lineage, detect clonality and maturation arrest, and identify targets such as CD20 or CD30.

A clonal myeloid neoplasm causing ineffective hematopoiesis, cytopenias, and dysplasia in one or more lineages; diagnosis combines morphology with cytogenetics and molecular findings, and blast percentage determines classification.

A gain-of-function mutation in the JAK2 pseudokinase domain found in nearly all polycythemia vera and roughly half of essential thrombocythemia and primary myelofibrosis cases, producing constitutive cytokine-independent signaling.

The fusion product of t(9;22) that constitutively activates tyrosine kinase signaling; it defines chronic myeloid leukemia, appears in some acute lymphoblastic leukemias, and is the target of tyrosine kinase inhibitors.

The proportion of immature blasts among marrow or blood nucleated cells, usually counted on a 500-cell differential; 20% or more separates acute leukemia from myelodysplastic and chronic myeloid neoplasms.

Disease remaining below the threshold of morphologic detection, measured by multiparameter flow cytometry, PCR, or next-generation sequencing; MRD levels guide risk stratification and treatment decisions in leukemia and myeloma.

A hyperinflammatory syndrome with fever, cytopenias, splenomegaly, high ferritin, low fibrinogen, and hemophagocytosis; diagnosed by HLH-2004 criteria and treated urgently with immunosuppression and etoposide-based regimens.

The lowest antimicrobial concentration that visibly inhibits growth of an organism in a standardized broth or agar dilution test; reported with a categorical interpretation derived from species-specific breakpoints.

A concentration threshold published by CLSI or EUCAST that converts an MIC into susceptible, intermediate, or resistant categories, accounting for dosing, pharmacokinetics, and known resistance mechanisms.

A carbapenem disk is exposed to the isolate, then placed on an indicator strain; absence of inhibition shows that the isolate hydrolyzes the drug, indicating carbapenemase production.

Mass spectrometry that compares a colony's protein spectrum against a reference library, identifying bacteria and yeasts to species level in minutes and largely replacing biochemical panels.

A periodic summary of percent susceptible by organism and antimicrobial, ideally restricted to first isolates and stratified by specimen type, used to guide empiric therapy and monitor resistance trends.

Diagnosis relies on detecting toxigenic C. difficile, by nucleic acid amplification or toxin immunoassay, often in a two-step algorithm, and should be limited to unformed stool from patients with compatible diarrhea.

The interval from incubation to instrument flagging of growth; shorter times imply higher bacterial burden and correlate with severity, while some fastidious or slow-growing organisms need extended incubation.

United States regulatory categories (waived, moderate, high) based on operational steps, calibration, and interpretation, which set the personnel qualifications, quality control, and oversight a laboratory must provide.

External samples with unknown values that a laboratory tests and submits for comparison with peer or reference results; unacceptable performance triggers investigation, corrective action, and possible loss of accreditation.

A set of control rules (1-2s, 1-3s, 2-2s, R-4s, 4-1s, 10x) applied to quality control results to distinguish random from systematic error and decide whether to accept or reject an analytical run.

Verification confirms that a cleared method performs as the manufacturer claims for accuracy and precision; validation establishes performance from scratch for laboratory-developed or substantially modified methods lacking such claims.

A structured, nonpunitive review after an error or adverse event that maps the process and identifies contributing system factors, using tools such as the five whys and cause-and-effect diagrams, to prevent recurrence.

A prospective risk assessment listing process steps, potential failure modes, and their severity, occurrence, and detectability, ranked by risk priority number so that resources target the highest-risk steps first.

A standard vocabulary that assigns codes to laboratory tests and observations, allowing results to be exchanged and aggregated electronically across different information systems and institutions.

Documented evaluation of staff at defined intervals through direct observation, review of results and quality data, and problem-solving scenarios, required by accreditors before independent testing and at least annually thereafter.