The Practical Lab Flashcards
Which blood tubes contain anti-coagulant and which do not?
Serum - clotted
Heparin, EDTA, citrate, oxalate - anti-coagulant
What do we see on biochemistry if there has been EDTA contamination?
Artificial hypocalcaemia and hyperkalaemia
Which liver parameters are markers of hepatocellular damage?
ALT, AST, GLDH, SDH
Which liver parameters are markers of cholestasis?
Cholestasis = bile not moving as it should, not moving into intestines (bile duct closed)
ALP, GGT
Which liver parameters are markers of function?
Substances produced in liver - cholesterol, urea, glucose, albumin, some globulins, coagulation factors
Substances conjugated and excreted by liver - bile acids, bilirubin
What can cause primary hepatocellular disease?
Trauma
Toxins
Drugs
Inflammation/infection
Neoplasia
Intrahepatic cholestasis
Bile toxicity
What biochemistry changes reflect decreased hepatic function?
Increased levels of things supposed to be excreted by liver: bilirubin, bile acids
Decreased levels of things made by liver: albumin, cholesterol, urea, glucose, clotting factors
What does a stress leukogram look like?
Neutrophilia
Monocytosis
Lymphopaenia
Eosinopaenia
What characteristics of lesions are useful for clinical history?
Localisation
Firm/soft
Dimensions
Painful/non-painful
Ulcerated/non-ulcerated
Cutaneous/subcutaneous
Adherent/non-adherent
Aspirate appearance
What are the two methods of fine needle aspiration (FNA)?
Non-suction
Suction (when non-suction technique is unsuccessful)
Describe non-suction FNA.
Soft cutaneous/subcutaneous masses
Lymph nodes
Vascular lesions/organs
Needle inserted into mass, syringe removed and filled with air, syringe attached to needle
Describe suction FNA.
Hard cutaneous/subcutaneous masses
Bone lesions
Needle and syringe inserted into mass, plunger pulled back, vacuum created in syringe, release plunger before removing needle from mass
What other collection methods are there for cytology samples?
Impression smear
Skin scrapes
Biopsy - imprint
Ear swab - imprint
Describe Malassezia on ear swabs.
Fungus - yeast
Peanut-shaped
Present in low numbers on normal skin
Describe Diff-Quik staining.
Solution A (fixation) - methanol
Solution B (eosinophilic (base) staining - eosin
Solution C (basophilic (acid) staining) - methylene blue
What should we look for on low magnification (10x) of cytology?
Cellularity
Preservation
Staining
Haemodilution
Cell distribution
Background
What should we look for on high magnification (40x) of cytology?
Cellular vs non-cellular elements
Inflammatory vs neoplastic
Malignant vs benign
What should we look for on high magnification (100x) of cytology?
Presence of cytoplasmic granules
Nuclear detail
Presence of pathogens - bacteria, fungi, protozoa
Describe neutrophils.
Crisp nuclear outlines with dark purple chromatin
Cytoplasm pale, clear to slightly eosinophilic (pink)
Describe degenerate neutrophils.
Neutrophils affected by toxic change
Loss of segmentation
Lighter coloured ‘fluffy’ nuclear chromatin and swollen appearance
What are the advantages of in-house labs?
Fast turn-around time
Potential for improved monitoring
Smaller volume of sample needed
Available OOH/in remote areas
May save costs
Define inter-individual factors that affect results.
Inherent difference between groups of animals due to effects of species, breed, age and/or sex
Define intra-individual factors that affect results.
Transient differences in the same animal
Eg. diet, stress/excitement, reproductive status, drugs, method/site of blood sampling
What pre-analytical factors can affect results?
Poor blood sampling technique
Haemolysed, lipaemic, icteric plasma
Wrong anticoagulant to blood ratio
Sterile vs non-sterile container
Transportation
Storage
What analytical factors can affect results?
Equipment e.g. function/maintenance
Technician e.g. training
Analytical procedure e.g. technique, calibrations
Laboratory e.g. temperature, humidity
How do we carry out quality control?
Control material of known composition is measured to check accuracy of analytical process
Performed during analysis to ensure validity of result
Controls are not calibrators
What should we do if a control fails?
Check for reagent depletion/expiry, mechanical faults, clots
Use another aliquot of control material
Repeat control
Use new reagent, recalibrate equipment
Run routine maintenance
Consult manufacturer
What post-analytical factors can affect results?
Transfer of results to patient record
Archiving results
Storing specimens
