Clinical Testing & Analysis Flashcards
7 cards from real MLS practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Clinical Testing & Analysis flashcards as text
A type and screen is ordered pre-operatively. The antibody screen is positive. What is the next step?
Answer: Perform antibody identification panel
A positive antibody screen requires an antibody identification panel to determine the specificity of the unexpected antibody before blood is issued.
In cerebrospinal fluid analysis, xanthochromia is most commonly caused by:
Answer: Oxyhemoglobin and bilirubin from red cell breakdown
Xanthochromia results from oxyhemoglobin and later bilirubin released as RBCs lyse after subarachnoid hemorrhage, distinguishing it from a traumatic tap.
Which mycobacterium is the most common cause of pulmonary tuberculosis in immunocompetent US adults?
Answer: Mycobacterium tuberculosis
Mycobacterium tuberculosis is the etiologic agent of classic tuberculosis and remains the leading mycobacterial pathogen in immunocompetent individuals.
A serum potassium is critically elevated. The specimen is hemolyzed. What should the laboratory do?
Answer: Reject the specimen and request a recollect
Hemolysis releases intracellular potassium, falsely elevating serum K⁺; the specimen must be rejected and a fresh non-hemolyzed sample collected for accurate results.
Which coagulation test is used to monitor unfractionated heparin therapy?
Answer: Activated partial thromboplastin time (aPTT)
Unfractionated heparin potentiates antithrombin to inhibit intrinsic pathway factors, which is measured by the aPTT; therapeutic range is typically 1.5–2.5× control.
On a peripheral smear, which cell morphology is most characteristic of iron-deficiency anemia?
Answer: Microcytic hypochromic cells with pencil cells
Iron deficiency produces small, pale RBCs (microcytic/hypochromic) with elongated pencil cells due to reduced hemoglobin synthesis.
A urine culture grows >100,000 CFU/mL of a lactose-fermenting gram-negative rod. Oxidase is negative. Most likely organism is:
Answer: Escherichia coli
E. coli is oxidase-negative, lactose-fermenting, and is the most common cause of community-acquired urinary tract infections at significant colony counts.