Diagnostic Imaging and Laboratory Procedures
This domain tests safe radiography, ultrasound assistance, sample handling, and common laboratory tests with interpretation limits.
Imaging basics
Take orthogonal views, such as lateral and ventrodorsal or dorsoventral, rather than one view. Position correctly, collimate, and use PPE and dosimetry. Label patient, date, and view. Contrast studies require patient preparation and veterinarian direction. Ultrasound is operator dependent, so keep a systematic image record.
Laboratory basics
Match the tube to the test: EDTA for hematology, heparin or serum separator for chemistry, and citrate for coagulation. Avoid hemolysis and lipemia. Perform packed cell volume and total solids, blood smear, urinalysis, fecal flotation, cytology, and culture as ordered.
Worked example
A microhematocrit tube is centrifuged and the packed red cell layer is 15 mm in a total plasma column of 50 mm. Reasoning: PCV = 15 ÷ 50 × 100 = 30%. Read the plasma color and total solids separately. A 30% PCV may be low for a dog but is within the cat reference range, so interpret with species and clinical signs.
Quality control
Run controls, check expiry, and record results. Refrigerate samples only when the test allows it. Deliver cytology and biopsy samples promptly.
Traps
Relying on a single radiographic view; mislabeling a slide; using the wrong tube; freezing whole blood; interpreting PCV without species; ignoring artifact from movement or poor positioning.