differential count
WBC differential / peripheral differential / leukocyte differential.
differential count measure
The relative and absolute number of each WBC type in peripheral blood.
five basic WBC types
Neutrophils, Lymphocytes, Monocytes, Eosinophils, Basophils.
calculation for absolute count
Absolute count = Relative % × Total WBC.
other names for neutrophils
Segs, PMNs, polys.
condition causing neutrophilia
Bacterial infection, inflammatory disease, CML.
shift to the left
Increase in immature neutrophils (bands/stabs).
eosinophils increase in conditions
Allergies, skin inflammation, parasitic infections, eosinophilic leukemia.
causes of eosinopenia
Stress and steroid exposure.
lymphocytosis occurs in conditions
Viral infections, infectious mononucleosis, CLL.
monocytes do
Ingest and digest foreign material during inflammation/infection.
diseases associated with monocytosis
TB, brucellosis, SBE, Hodgkin’s disease, monocytic leukemia.
basophilia seen in conditions
Leukemia, chronic inflammation, hypersensitivity reactions.
types of blood smears
Cover glass smear, wedge smear, spun smear, buffy coat smear, thick smear.
factors affecting smear thickness
Drop size, angle of spreader, speed, pressure.
ideal blood smear length
2/3 to 3/4 of the slide.
indicates a good feathered edge
A slight rainbow appearance.
better on average—slide or coverslip smears
Slide smears (easier to perform consistently).
main components of Romanowsky stains
Azure B (basic dye) + Eosin Y (acidic dye).
best stain for parasites and inclusion bodies
Giemsa stain.
normal appearance of RBC in Romanowsky stain
Orange to salmon pink.
causes of overstaining
Thick smear, prolonged staining, insufficient washing, alkaline stain.
causes of understaining
Thin smear, excessive washing, acidic conditions.
moth-eaten RBC appearance indicates
Water/drying artifact.
