NHPC BMLT key terms

The range of test values expected in a healthy reference population, usually spanning the central 95 percent of results, used to judge whether a patient's value is normal or abnormal.

A unitless measure of assay imprecision calculated as the standard deviation divided by the mean, expressed as a percentage, allowing comparison of variability across tests with different units.

A control chart that plots quality control results over time against mean and standard deviation limits, making shifts, trends, and random error visible to the laboratory technologist.

A set of statistical rejection criteria applied to control results, such as 1-3s, 2-2s, and R-4s, that flag random or systematic error and guide whether patient testing should be repeated.

A proficiency program in which an outside body sends unknown samples to the laboratory and compares its results with peer laboratories to verify ongoing analytical accuracy.

Daily testing of known control materials alongside patient samples to confirm that a method performs within defined limits before results are released.

The thin layer of white blood cells and platelets that forms between plasma and packed red cells after centrifuging anticoagulated whole blood, used for preparing smears and harvesting leukocytes.

The percentage of blood volume occupied by red cells after centrifugation of an anticoagulated sample, a simple measure of anemia or polycythemia also called hematocrit.

The average size of circulating red blood cells, calculated from hematocrit and red cell count, and used to classify anemia as microcytic, normocytic, or macrocytic.

A thin film of blood spread on a glass slide, stained and examined under a microscope to assess red cell shape and size, white cell morphology, and platelet adequacy.

The percentage of newly released immature red cells in blood, measured after supravital staining, which indicates whether the bone marrow is responding adequately to anemia.

The pretransfusion compatibility test in which donor red cells are tested against recipient serum, by immediate spin or antihuman globulin methods, to detect clinically significant incompatibility before transfusion.

A test of the patient's serum against reagent red cells of known antigen type to detect unexpected alloantibodies that could cause hemolytic transfusion reactions or hemolytic disease of the newborn.

A test using antihuman globulin reagent to detect antibodies or complement already bound to the patient's own red cells, as seen in autoimmune hemolysis or hemolytic disease of the newborn.

A differential staining method that divides bacteria into gram-positive organisms retaining crystal violet and gram-negative organisms decolorized and counterstained pink, guiding rapid presumptive identification.

An acid-fast staining technique that uses heat or phenol to drive carbol fuchsin into waxy mycobacterial cell walls, which resist decolorization by acid alcohol.

The laboratory process of isolating a pathogen in culture and testing its growth against a panel of antimicrobials to guide effective antibiotic therapy.

The lowest concentration of an antimicrobial agent that visibly prevents growth of the test organism under defined conditions, used to classify it as susceptible, intermediate, or resistant.

A summary table of the percentage of local isolates of each species that are susceptible to various antimicrobials, used to guide empirical therapy and monitor resistance trends.

A validated process that destroys or removes all viable microorganisms, including bacterial spores, from an object or surface, commonly by autoclaving, dry heat, or ethylene oxide.

The use of chemical or physical agents to reduce pathogenic microorganisms on inanimate surfaces or skin, without necessarily destroying bacterial spores.

A graded set of containment practices, equipment, and facility design requirements, from BSL-1 to BSL-4, matched to the risk group of the agents handled in a laboratory.

Infection control practices applied to all patients regardless of diagnosis, including hand hygiene, gloves, gowns, masks, and safe handling of sharps and body fluids.

Accidental percutaneous puncture by a contaminated needle or sharp, requiring immediate first aid, source assessment, post-exposure prophylaxis where indicated, and reporting under the institution's exposure protocol.

A patient's voluntary agreement to a procedure or test after receiving adequate information about its purpose, risks, benefits, and alternatives, documented before the act.

The professional and legal duty to protect patient health information from unauthorized disclosure, sharing results only with those entitled to receive them.

A documented, unbroken record of who collected, handled, stored, and transported a specimen, essential when results may be used in legal or medico-legal proceedings.

A mistake occurring before analysis, such as mislabeling, wrong tube, delayed transport, or improper collection, which is a leading cause of invalid laboratory results.

Sensitivity is the proportion of truly diseased people correctly identified by a test; specificity is the proportion of truly healthy people correctly identified as negative.

The probability that a person with a positive test result actually has the condition, which depends on test sensitivity, specificity, and the prevalence of disease in the population tested.

A plate-based immunoassay in which an enzyme-labeled antibody or antigen produces a color change proportional to the amount of target analyte, widely used for antibody and antigen detection.

A serological method in which antibodies cross-link particulate antigens, such as red cells or latex beads, to form visible clumps that indicate the presence of specific antibody or antigen.

A set of red cell surface antigens controlled by a single gene or closely linked genes, such as ABO or Rh, which determine transfusion compatibility and risk of alloimmunization.

The concentration of dissolved solute particles per kilogram of solvent, measured in body fluids to assess water balance and the concentrating ability of the kidney.

The volume of plasma cleared of creatinine per unit time, calculated from serum and urine creatinine with urine volume, and used to estimate glomerular filtration rate.

Examination of cerebrospinal fluid for cell count, protein, glucose, and microbiology, used to distinguish bacterial, viral, and other causes of meningitis.

A body fluid analysis that enumerates cells in a counting chamber and classifies them by type, helping to identify inflammation, hemorrhage, or malignancy in fluids.

A rapid intraoperative histopathology technique in which tissue is frozen, sectioned, and stained within minutes to give a provisional diagnosis that guides the surgeon during the operation.

Preservation of tissue in buffered formaldehyde solution, which cross-links proteins and maintains structure for paraffin embedding, sectioning, and routine staining.

The microscopic study of individual cells, often collected by exfoliation or fine needle aspiration, to detect malignancy, infection, or hormonal status.