Specimen Processing and Handling Questions and Answers Flashcards

What does the term 'interference' mean in the context of clinical chemistry specimen analysis?

Answer: The effect of an endogenous or exogenous substance in the patient specimen that affects the measured analyte result

Analytical interference occurs when a substance in the patient specimen (endogenous: hemoglobin, bilirubin, lipids; exogenous: drugs, biotin) affects the measured signal, producing a falsely high or low result.

A laboratory receives a synovial fluid specimen from a joint aspiration. Which finding on microscopic examination would confirm the diagnosis of gout?

Answer: Negatively birefringent needle-shaped crystals (monosodium urate) under polarized light microscopy

Gout is confirmed by the presence of negatively birefringent needle-shaped monosodium urate (MSU) crystals within or outside white blood cells under compensated polarized light microscopy.

What is the purpose of a 'pre-warming' technique when testing blood specimens from patients with cold agglutinins?

Answer: To prevent cold agglutinins from agglutinating red blood cells at room temperature, which would cause false CBC results

Pre-warming specimens at 37°C prevents cold agglutinins (IgM antibodies active at cold temperatures) from agglutinating RBCs at room temperature, which would falsely elevate MCV and falsely lower RBC count on the CBC.

In which situation would a laboratory be justified in rejecting a specimen and requesting recollection?

Answer: The specimen is a sodium citrate tube for PT testing that is only 60% full

An underfilled sodium citrate tube (only 60% full instead of the required 90-100% fill) has an improper blood-to-anticoagulant ratio that will falsely prolong PT and APTT, making it unacceptable for coagulation testing.

What is the Pasteur pipette best suited for in a clinical laboratory?

Answer: Transferring small volumes of fluid without requiring precise volume measurement

Pasteur pipettes are glass or plastic transfer pipettes without volume graduation marks, used for non-quantitative fluid transfer in tasks like decanting, adding drops of reagent, or specimen manipulation.

What is the clinical significance of detecting 'atypical lymphocytes' on a peripheral blood film in a young adult with fever, pharyngitis, and lymphadenopathy?

Answer: Suggests infectious mononucleosis caused by Epstein-Barr virus (EBV)

Atypical (reactive) lymphocytes in a young adult with the classic triad of fever, pharyngitis, and lymphadenopathy strongly suggest infectious mononucleosis caused by Epstein-Barr virus (EBV).