Clinical Pathology and Hematology Instruction
Clinical Pathology and Hematology Instruction covers how candidates teach CBC performance, smear evaluation, morphology, and interpretation. The exam tests preanalytical control, manual differential technique, species differences, and the ability to connect findings to a defensible interpretation.
Core rules
- Control preanalytics: appropriate tube, fill volume, mixing, timely processing, and avoidance of hemolysis.
- Make a wedge smear with a readable feathered edge; examine at 10x for distribution, then 100x oil for a 100-cell differential.
- Estimate platelet adequacy from the monolayer, confirm with a count when clumps or low numbers are seen, and scan for RBC morphology.
- Correct leukocyte interpretations for nucleated RBCs and note toxic change, left shift, or reactive lymphocytes.
- Teach species differences, such as feline stress leukograms and canine regenerative responses.
Worked example
A dog has pale plasma, polychromasia, and many reticulocytes after blood loss. The reasoning: anemia plus regeneration points to blood loss or hemolysis; the reticulocyte response and smear pattern support regeneration. A low reticulocyte count in a severely anemic dog would prompt concern for nonregenerative disease or early loss before response.
Traps
EDTA artifact, platelet clumping, overstained smears, counting too few cells, ignoring the feathered edge, and calling every blue cell a reactive lymphocyte. Also avoid interpreting a slide without the CBC and clinical context.