Complete blood count (CBC)
Sample Required:
Sample Type: Whole blood (EDTA – purple-top); Blood smear
Test Code: HCBC
Sample Handling:
-While only 0.3 mL of blood is needed to run a CBC, the correct size tube should be chosen to prevent excess EDTA affecting RBC parameters and smear quality.
-Fill EDTA tube as close to the mark as possible. Ensure the blood is mixed with the anticoagulant by gentle inversion of the tube 8-10 times immediately after collection.
If there is a delay in sending, store samples in the fridge.
-Make blood smear as soon after blood collection as practicable. Ensure the feathered edge of the blood smear does not extend to within ~15 mm of the ends of the slide. Allow to completely air dry before placing into the slide mailer. Store at room temperature.
Method:
SVS Laboratories has a Sysmex hematology analyser which employs laser flow cytometry for identification and counting of blood cells. Smear examination is performed manually.
Components:
• All elements of the ABC - haematocrit (HCT), haemoglobin (Hb), red blood cell count (RBC), mean corpuscular volume (MCV), mean corpuscular haemoglobin (MCH), mean corpuscular haemoglobin concentration (MCHC), white blood cell count (WBC), WBC differential.
• Manual smear examination which includes:
o Evaluation of red cell morphology including presence of blood parasites;
o A manual white blood cell differential for comparison with the automated differential, in case of features that may be mis-identified by the analyser (e.g., immature or atypical white blood cells) and evaluation of white blood cell morphology (e.g., neutrophil toxic change, reactive or neoplastic lymphocytes);
o Assessment for platelet clumps, estimation of platelet numbers, and evaluation of platelet morphology.
• Further manual testing (e.g., reticulocyte % and absolute reticulocyte count, saline agglutination test) when the provided history or routine CBC results indicate that these are required.
• Fibrinogen level (via the heat precipitation method) is provided routinely with all production animal and equine CBCs.
References:
Reviewed: June 2025