Sampling Techniques Flashcards
What is cytology?
It is the study of cell number and type in a tissue mass of fluid accumulation to investigate its cause (usually inflammation or neoplastic).
Name three things cytological examination should enable?
- Differentiation of different fluid types e.g. transudate vs exudate
- Differentiation of type of inflammation e.g. eosinophilic, neutrophilic, granulomatous (fungal)
- Detect the presence of neoplasia.
What are the 4 scenarios which might lead to a false negative?
- The tumour might not exfoliate very well
- Might not have got cells from the right sample site
- Extensive inflammation around the tumour can look like ordinary inflammation
- Tumour might not be well enough differentiated to allow an accurate diagnosis.
What might cause a false positive?
Dysplasis can mimic neoplasia and occurs in inflammatory disease.
What is histopathology?
The study of changes in tissues caused by disease.
What is FNCS and how is it performed?
Fine needle capillary sampling - no suction- needle with no syringe attached
What is FNA and how is it performed?
Fine Needle Aspirate - minimal suction
When would you use FNA?
Cysts or failed FNCS - needle and syringe attached
What can we determine from fluids?
Their classification and tissue of origin.
What is a lavage and where could it be used?
Saline is used to wash nasal, bronchoalveolar, urinary bladder mucosa and the resulting fluid is collecting by collecting of the immediate lavage.
What tubes would you use to collect lavage samples?
Split between EDTA and sterile tubes.
When do lavage samples need to be processed?
As soon as possible.
What is the most sterile collection method of urine?
Cystocentesis
Is a little body cavity fluid normal?
A little is normally present, however too little to collect, unless in horses.
What causes profound amounts of cavity fluid?
Hypoproteinaemia.
What is BAL?
Bronchoalveolar lavage
How is BAL performed?
Place catheter into the trachea, add saline and quickly aspirate. The fluid is then centrifuged and a smear is made from the centrifuged sediment.
What is bronchoscopy?
Viewing with a camera - cells can be removed with a tiny brush
What is a problem with broncho-alveolar lavage?
Might pick up bacteria from the pharynx.
What are the 4 basic tests applied to fluid samples?
- Appearance of fluid
- Cell type
- Total protein content
- Total nucleateWd Cell Ceount (TNCC)
What are the two methods to prepare a slide for cytological examination?
- ‘wedge’ method
2. Flat-Slide method
What have you got to be careful of when preparing a smear?
not to CRUSH the cells
If the fluid is turbid, what should you do?
make the smear directly on the glass slide.
If the sample fluid is clear, what should you do?
Centrifudge the fluid and smear the sediment (might be a low cell count).
What type of centrifuges are used to yield cells when the cell count is low?
Cytocentrifuges.
Once you have got your smear, what should you do?
Air-dry rapidly and stain
What happens if you don’t dry rapidly?
All sorts of artefacts
For how long and what speed should a bench centrifuge be used?
5 mins at 500-1000rpm
What can biopsy and necropsy tissues be used for prior to sticking in formalin?
To make impression smears for a rapid preliminary diagnosis.
What is the benefit of taking an impression smear before sending the sample of for histopathology?
Histopathology can take weeks and impression smears give us a preliminary idea.
What is a rule regarding cytology and formalin
KEEP CYTOLOGICAL SAMPLES AWAY FROM FORMALIN FUMES.
What effect does formalin have on a cytology smear?
Ruins it.
What should you NEVER do with wet slides following FNA and why?
Never put wet slides in the carrier box as they will start to rot.
What 5 things should be included with the smears?
- Description of the mass
- Location
- Size
- Growth rate
- Texture
Name 5 types of Romanowsky blood stains?
- Diff-Quick
- Dip-Quick
- Wright’s
- Giemsa
- Leishman
What stain would be used for Mast cells?
Toluidine Blue
What stain would be used for mucin?
PAS - periodic acid schiff
Name 4 stains that could be used if microorganisms were present?
- Gram
- Ziel-Nielsen
- Fontana
- PAS
What are the 6 types of effusion categories?
- Exudate
- Transudate
- Haemorrhage
- Lymphorrhage
- Organ rupture
- Mixture of above
What is g/dl x 10?
g/L
What is transudate?
Excessive diffusion of plasma water from vasculature (transudation).
Name two reasons for increased transudate?
- Increased hydrostatic pressure e.g. hypertension (Na+ retention, increased alveolar capillary pressure)
- Decreased COP (hypoproteainaemia, hypoalbuminaemia)