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Section 2 of 6 · Open sections

Required section · Section 2 of 6

Sort the pattern before naming a cause

Macro-ovalocytes are enlarged oval red cells; hypersegmentation means a neutrophil with more nuclear lobes than expected. Together they support a megaloblastic pattern of impaired DNA synthesis. Dysplasia means abnormal cellular maturation and requires qualified morphology review; it is not established by one automated result. Round macrocytes fit nonmegaloblastic patterns and redirect the differential.

Reticulocytes are larger than mature red cells, so a regenerative response can increase MCV. Increased reticulocytes prompt correlation for hemolysis, blood loss, or recovery after treatment. Low reticulocytes in the guided case argue against a regenerative explanation.

Illustrative drawing — this picture was drawn rather than captured.

Two-branch macrocytosis map separates macro-ovalocytes and hypersegmented neutrophils from round macrocytes and then directs use of functional markers or reticulocyte response.
Figure 1Two-branch map for organizing macrocytosis.

Review sequence for an increased MCV

  1. Confirm the result

    Review specimen condition, analyzer flags, count, hematocrit, and local smear-review criteria.

  2. Classify morphology

    Distinguish macro-ovalocytic findings with hypersegmented neutrophils from round macrocytosis or concerning dysplasia.

  3. Assess reticulocytes

    Determine whether an increased reticulocyte response can account for the MCV.

  4. Target correlation

    Use nutrient markers, renal context, chemistry, thyroid testing, medication context, and qualified review as appropriate.

Knowledge checks

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Knowledge check 1

Which smear combination most supports an impaired DNA synthesis pattern?

Choose one option.

Knowledge check 2

What does an increased reticulocyte response most directly prompt in macrocytosis?

Choose one option.

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