Laboratory Procedures and Diagnostic Imaging
Laboratory Fundamentals
Understand sample collection, handling, and the preanalytical errors that invalidate results. Know the differences between serum and plasma, the purpose of anticoagulants (EDTA for CBC, heparin or citrate for coagulation), and the effects of hemolysis, lipemia, and icterus. Familiarize yourself with the complete blood count, serum chemistry panels, urinalysis, and cytology.
Diagnostic Imaging
Know the principles of radiography (positioning, exposure, contrast, radiation safety) and ultrasonography (acoustic windows, artifact recognition). Understand when radiography versus ultrasound is preferred, and the role of contrast studies. Radiation safety-ALARA, shielding, dosimetry badges-is a frequent topic.
Interpreting Results
Technicians must recognize normal versus abnormal values and understand that reference ranges vary by species, age, and lab. Correlate lab data with clinical signs.
Traps to Watch
Questions may ask which tube to use for a specific test or confuse hemolysis with lipemia. Another trap is assuming all species share reference ranges or that a single abnormal value is diagnostic.
Worked Example
A sample collected in a plain red-top tube is clotted and unsuitable for a CBC. The correct tube is lavender-top (EDTA), which preserves cell morphology.
Rule of Thumb
Match the tube to the test: EDTA for CBC, heparin or citrate for coagulation, plain or serum separator for chemistry.