RBC Morphology Hematology Review 300
ABNORMALITY DESCRIPTION SIGNIFICANCE
Size
Anisocytosis
Macrocytes
Microcytes
Shape
Poikilocytosis
Elliptocytes/ovalocytes
Crenated RBCs
Burr cells (echinocytes)
Acanthocytes (spur cells)
Variation in size.
RBCs >9 μm.
RBCs <6 μm.
Variation in shape.
Oval or pencil/cigar shaped.
Round cell with knobby, uniform
projections.
Round cell with evenly spaced blunt or
pointed projections.
Small, dense cells with irregularly
spaced projections of varying length.
Seen in many anemias.
Megaloblastic anemias, liver disease, reticulocytosis. Normal
in newborns.
Iron deficiency anemia, thalassemia, anemia of chronic
infections.
Seen in many anemias.
Membrane defect. Hereditary ovalocytosis, various anemias.
Osmotic imbalance. If seen in most cells in thin part of smear,
don’t report. Probably artifact due to excess anticoagulant or
slow drying.
Membrane defect. Uremia, pyruvate kinase deficiency. May
be drying artifact. A few can be present in healthy individuals.
Membrane defect. Severe liver disease, abetalipoproteinemia.
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