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MLPAO Hematology and Coagulation Case Studies Flashcards

6 cards from real MLPAO practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.

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  1. A patient has PT 18 seconds (normal 11-14), aPTT 45 seconds (normal 25-35), low fibrinogen, elevated D-dimer, and schistocytes on smear. What is the most likely diagnosis?

    Answer: Disseminated intravascular coagulation

    The combination of prolonged PT and aPTT, low fibrinogen, elevated D-dimer, and schistocytes is the classic laboratory picture of DIC. This consumptive coagulopathy results in simultaneous coagulation factor consumption, fibrinolysis activation, and microangiopathic hemolysis. The underlying cause must be identified and treated.

  2. A peripheral smear shows red blood cells with a central pallor extending over more than one-third of the cell diameter. What does this indicate?

    Answer: Hypochromia (decreased hemoglobin content)

    Hypochromia is characterized by increased central pallor (>1/3 of cell diameter) indicating decreased hemoglobin content. This is commonly seen in iron deficiency anemia and thalassemia. The MCH and MCHC values will also be decreased. It reflects insufficient hemoglobin filling the red blood cell.

  3. A patient with a mechanical heart valve has an INR target of 2.5-3.5. Their current INR is 2.0. What action should be taken?

    Answer: Increase the warfarin dose slightly to achieve the higher target range

    Patients with mechanical heart valves require higher INR targets (typically 2.5-3.5 depending on valve position and type) compared to patients with atrial fibrillation or venous thromboembolism (target 2.0-3.0). An INR of 2.0 is below the therapeutic range and requires a modest dose increase.

  4. A technologist notices that the automated WBC count is 25 × 10⁹/L but the histogram shows a suspicious population. The peripheral smear shows many nucleated red blood cells (NRBCs). What should be reported?

    Answer: A corrected WBC count after subtracting NRBCs from the total count

    NRBCs have nuclei and are counted as WBCs by automated analyzers that use lysis-resistant nuclear counting. The WBC count must be corrected using the formula: Corrected WBC = (Automated WBC × 100) / (100 + NRBC per 100 WBC). The presence of NRBCs and the corrected count should both be reported.

  5. A patient presents with prolonged aPTT that does not correct on mixing study. Incubated mixing studies show further prolongation. What is the most likely diagnosis?

    Answer: Factor VIII inhibitor (time-dependent)

    A time-dependent factor inhibitor (most commonly Factor VIII inhibitor) shows partial or no correction on immediate mixing, with further prolongation after incubation at 37°C for 1-2 hours. This is because the antibody is time- and temperature-dependent. In contrast, lupus anticoagulant shows immediate non-correction without progressive prolongation on incubation.

  6. A blood smear shows bite cells and Heinz bodies on a supravital stain. The patient recently started taking a sulfonamide antibiotic. What is the most likely diagnosis?

    Answer: Glucose-6-phosphate dehydrogenase (G6PD) deficiency with oxidative hemolysis

    Bite cells (degmacytes) result from splenic removal of Heinz bodies (denatured hemoglobin precipitates). This pattern triggered by an oxidizing drug (sulfonamide) is classic for G6PD deficiency. The deficient enzyme cannot generate adequate NADPH to maintain reduced glutathione, leaving hemoglobin vulnerable to oxidative damage.