ASCP MLS flashcards

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

Rh immune globulin dose

A 300 microgram dose of RhIG neutralizes about 15 mL of fetal red cells or 30 mL of fetal whole blood and is given at 28 weeks and within 72 hours postpartum.

Acute hemolytic transfusion reaction

Usually caused by ABO-incompatible red cells from a clerical or identification error, presenting with fever, chills, flank pain, hemoglobinuria, and a positive DAT; stop the transfusion immediately.

Weak D testing

Donor units are tested for weak D by the indirect antiglobulin technique so that D-positive units are not mislabeled as D-negative and given to D-negative recipients.

Enzyme treatment in antibody ID

Ficin or papain enhances Rh, Kidd, Lewis, and P1 antibodies but destroys Duffy and MNS antigens, helping separate these specificities during panel interpretation.

Platelet storage conditions

Platelets are stored at 20-24 degrees Celsius with continuous gentle agitation for up to 5 days; refrigeration causes shape change and rapid clearance from circulation.

Anion gap calculation

Anion gap equals sodium minus the sum of chloride and bicarbonate, with a reference of 8-12 mmol/L; add 2.5 for each 1 g/dL albumin below 4.0.

Friedewald LDL formula

LDL cholesterol equals total cholesterol minus HDL cholesterol minus triglycerides divided by 5; the estimate is invalid when triglycerides exceed 400 mg/dL.

Calculated serum osmolality

Equals 2 times sodium plus glucose divided by 18 plus BUN divided by 2.8; an osmolal gap above 10 suggests ingestion of methanol, ethylene glycol, or isopropanol.

HbA1c interpretation

Reflects average glycemia over the preceding two to three months; results are falsely low with hemolysis or blood loss and unreliable in end-stage renal disease or with hemoglobin variants.

Reticulocyte production index

Corrects the reticulocyte percentage for anemia by multiplying by the patient hematocrit divided by 45, then dividing by a maturation factor of 1 to 3.

Iron deficiency vs chronic disease anemia

Iron deficiency shows low ferritin, high TIBC, and saturation below 20%; anemia of chronic disease shows low iron and low TIBC with normal or elevated ferritin.

Mixing study interpretation

A prolonged PT or aPTT that corrects after 1:1 mixing with normal plasma indicates factor deficiency; failure to correct indicates an inhibitor such as lupus anticoagulant or a factor antibody.

LAP score

Leukocyte alkaline phosphatase activity is low in chronic myeloid leukemia and high in leukemoid reaction, helping separate the two while BCR-ABL1 testing is pending.

CD markers in hairy cell leukemia

Hairy cells coexpress CD11c, CD25, CD103, and CD123 and are tartrate-resistant acid phosphatase positive, distinguishing them from other chronic B-cell lymphoproliferative disorders.

Complement classical pathway

Initiated when C1q binds IgG or IgM, activating C1r, C1s, C4, C2, and C3; terminal components C5 through C9 assemble the membrane attack complex.

Type III hypersensitivity

Circulating immune complexes deposit in tissues such as glomeruli and joints, activating complement and recruiting neutrophils; examples include serum sickness and post-streptococcal glomerulonephritis.

Prozone phenomenon

Antibody excess in precipitation or agglutination assays prevents lattice formation and produces a false-negative result; diluting the sample restores a detectable reaction.

Optochin and bacitracin disks

Streptococcus pneumoniae is optochin sensitive and bile soluble; group A streptococci are bacitracin sensitive, while group B are bacitracin resistant and CAMP positive.

MacConkey lactose fermentation

Lactose fermenters such as Escherichia coli form pink colonies; nonfermenters such as Salmonella and Shigella remain colorless, and Salmonella often shows black centers from hydrogen sulfide.

CSF findings in bacterial meningitis

Bacterial meningitis shows neutrophilic pleocytosis, markedly low glucose, and high protein; viral meningitis shows lymphocytes with normal glucose and only mildly elevated protein.

Germ tube test

Candida albicans forms germ tubes after incubation in serum at 37 degrees Celsius for two to three hours, distinguishing it from other Candida species.

Real-time PCR threshold cycle

Ct is the cycle at which fluorescence crosses a defined threshold and is inversely proportional to the amount of target nucleic acid present initially in the sample.

FISH for BCR-ABL1

Fluorescence in situ hybridization detects t(9;22) in interphase nuclei without cell culture, supporting rapid diagnosis and residual disease monitoring in chronic myeloid leukemia.

Southern, Northern, Western blots

Southern blot detects DNA, Northern blot detects RNA, and Western blot detects protein; each separates molecules by size before specific probe or antibody detection.

Dysmorphic red cells in urine

Acanthocytes and other dysmorphic red cells indicate glomerular bleeding, whereas uniform isomorphic red cells suggest bleeding from the lower urinary tract.

Light criteria for exudate

Pleural fluid is exudative if the fluid-to-serum protein ratio exceeds 0.5, the LDH ratio exceeds 0.6, or fluid LDH exceeds two-thirds of the serum upper reference limit.

Urine leukocyte esterase and nitrite

Leukocyte esterase detects neutrophil esterases and nitrite reflects nitrate-reducing gram-negative bacteria; both positive supports urinary tract infection, but culture is required for confirmation.

Triple phosphate crystals

Struvite crystals appear as colorless coffin-lid shapes in alkaline urine and are associated with urease-producing organisms such as Proteus in struvite stone formation.

Westgard 1-3s rule

A single control value exceeding three standard deviations from the mean rejects the analytical run and is the most commonly applied random error rule on a Levey-Jennings chart.

Sigma metric calculation

Sigma equals total allowable error minus bias, divided by the coefficient of variation; six sigma indicates world-class performance while four sigma requires close monitoring and corrective action.

Positive predictive value

Positive predictive value equals true positives divided by the sum of true positives and false positives; unlike sensitivity and specificity, it depends on disease prevalence.

Delta check

Compares a current patient result with the previous value to flag clinically implausible changes, helping detect specimen mix-ups, mislabeling, and analytical error before results are released.