Laboratory Flashcards
What is a quality control sample and what types of samples can be used?
A sample with known measurable parameters.
Liquid- fresh blood, or frozen serum(biochem) short expiration.
Freeze dried lyophilised-long storage life requires reconstitution, these can then be frozen
How should a quality control sample be tested?
Normal parameter and abnormal parameters should be analysed in quality control tests.
What are the characteristics of haematology QC and how should they be analysed?
Commercial QC samples are available, dervied from human blood PPE.
Expected mean values and upper and lower tolerance limits are provided by the sample manufacturers.
3 samples are provided one with normal parameters the others with low and high parameters.
Always analyse at room temperature temperature
Mix well before analysis
QC should be run every day normal and abnormal
What are the characteristics of biochemistry QC and how should they be analysed?
Derived from animal blood, can be frozen serum or freeze dried lyophilised seru (preferred)
Expected mean values and upper/lower limits are provided
2 to3 levels of control high normal low
Store according to guidelines
Accurate pipetting
Run one quality control sample each week
How should QC samples be recorded?
In a dedicated notebook (name operator, date,batch number, all results) plot on a Levy Jennings graph.
Parameter being analysed is on the y axis days of the month on the x axis horizontal lines are where the upper and lower limits are set A separate share is created for each test and each control level
How should the results of a quality control test be analysed?
If the control values fall within the 2sd range the value is accepted.
If a control value is outside the 3SD range or both values from two levels of control are outside the 2SD range or when a fresh control is mixed properly and ran again and the value is still outside the 2SD range
What should be done if the quality control sample does not produce accurate results?
Check the equipment (recalibration) reagent(out of date storage) and control sample.
Examin the levy Jennings values over time identifies specific trends
What is a quality assurance scheme?
Organised by labs aim to assess the quality of labs across the country.
Send samples to lab every 2-4 weeks. Samples are run and sent back to organiser. Organiser grades the labs performance in relation to all other labs. Not practical in practice send off known sample to the lan to be analysed
What are the three main guidelines for reproducing good lab results?
Good samples!! Pre-analytical error- sample collection, storage, handling, shipping conditions, condition of patient, drugs)
analytical error- lipaemia haemolysis non separated samples.
Post analytical error
What must always be sent with a blood sample to the lab?
Fresh blood smear
What is the main use for EDTA
Preserve cells in whole blood for haematology. Serum can be used to analyse hormone assays glucose
What is citrate used for(sodium citrate)
Binds calcium, when centrifuges produces citrates plasma. Remove plasma place into plain tube freeze or refrigerate.
Coagulation tests
Sodium fluoride used for?
Week anti coagulant prevents cells from utilising glucose prevents enzymes from completing glycolysis cannot be used for measuring urea.
What is a heparin tube used for?
Obtaining plasma
only week binding with calcium most of the action is through anti thrombin use lithium salts type if need plasma for biochem
Can effect t3 and t4 binding to carrier proteins higher levels in blood
Can interfere with some calcium assays
What are additive free tubes used for?
For blood collection for separation of serum. For biochem tests bile acids serology immunology
Hormone tests
Always wait for clot formation before centrifuging 20-30minutes
What are Separator tubes?
Contain gel that once the sample has been centrifuges keeps the cells away from the seru. Preventing any in vitro metabolic changes to the serum
What are the effects of stress and excitement on blood samples?
CBC stress response increase neutrophils decrease lymphocytes
Increased glucose in cats
Increased cortisol
What are the effects of a GA on lab results?
CBC stress responses
May effect RBC count
WBC count
Induce liver enzymes
What are the effects of steroids and antibiotics on lab results?
Thyroid pituitary axis Glucocorticoids- suppression of pituitary adrenal axis 12-36 hrs Decrease amylase levels Increase lipase levels Increase glucose Increased ALP
What are the effects of bromide therapy (seizure control) on lab results?
Interfere with the measurements of chloride false high
Phenolbarbital effects on lab results?
Induce ALP increase Liver enzymes
Decrease thyroid hormone levels
The effects of diuretics on lab results?
Dehydration
CBC pre renal Azotaemia
Hyperkalaemia
Increased protein and albumin
Main problems during analysis of samples are?
Lipaemia- inadequate fasting post paradisal sample
Haemolysis-inadequate sampling too much forceinterfere with plasma protein measurements
Non separated samples- glucose levels incompatible(use fluoride Ocala the if cannot separate)
Potassium will leak from cells
What tube should you use for morphology and cell counts?
EDTA
What tube should you use for protein and albumin, biochemistry?
Plain
What tube should you use for glucose and lactate?
Fluoride oxalate
What tube should you use for bacteriology?
Sterile
How should fluid samples be collected?
Two tubes one sterile (culture) one EDTA make smear
How should urine samples be collected and stored?
Cystocentesis
Store for less than 30 minutes or refrigerate 1-12 hours re warm before analysis
What tubes should be used to collect urine for sediment analysis?
Boric acid (sediment stained, prevents bacterial growth)
Plain (non sediment stained)
Prepare smears from centrifuged nothing preserves casts
What are the indications for cytology?
Cutaneous and subcutaneous masses Lesions Lymphoma nodes Pleural effusion Abnormal effusions Joint diesease CSF disease
What are the 4 types of cytology sampling techniques?
Fine needle aspirate
Scraping
Impression smear
Swab smear
What are the two tyoes of FNA techniques
No suction- only use the needle and direct needle in different areas of mass
Continuous suction- 5ml syringe 21g needle, immobilise mass insert syringe maintain suction whilst moving the syringe backwards and forwards
What three techniques are used to make cytology smears?
Blood smear-less harmful to cells
Squash smear- potential for damage good quality smears
Line concentration technique- good for haemodiluted samples!
What techniques should be used to aspirate lymphoma nodes?
Needle only
What techniques aids sampling of internal masse?
Ultrasound
How should cytology samples be prepared?
EDTA smears staining( Romanosky stain Giesmas, leishmans, rapid stains) centrifuge
What can cytology tell us?
Inflammatory (sterile, infected)
Non inflammatory neoplasticism hyperplastic Dysplastic
What should you look for on a slide?
Inflammation haemorrhage, tissue cells present
What are the cellular criteria for malignancy?
Ununiformed, large cells, abnormal location, loss of cohesion, chaotic cell formations, various sizes Multinucleation Nuclear molding Increased nuclear cytoplasmic ratio Chromatin changes Fusiform shaped (spindle)
