Cytology Flashcards
Define cytology
The medical and scientific study of cells
What are the benefits of cytological analysis?
Relatively inexpensive
Identification inflammatory cells
Can be quick and easy
Identification of stages of reproduction
Identification of pathogenic cells
Identification of neoplastic cells
Give examples of cytology samples
Bone marrow
Synovial fluid - joint tap
Cerebral spinal fluid - LP
Neoplasia - FNA
How do we obtain a sample?
Fluid aspiration
Scrapes
Fine needle aspiration
Impression smear
Fine needle - non aspiration
Swabs
CSF cells degrade rapidly. In what time scale from sampling should they be analysed?
30-60 minutes
When might an FNA be used?
Neoplasia
Inflammatory mas
Abscess
Lymph node
What are the advantages of FNA?
Quick and easy
Cheaper than surgical biopsy but less diagnostic
Minimal trauma to patient
Can be performed on conscious patient, but sedation may be required
Can be done by RVN
What gauge needle should be used for an FNA?
Less than 20g
How quickly should the sample be analysed?
Within 5-10 minutes to prevent degradation of sample
Describe the aspiration technique
Performed using a needle and syringe, with the syringe used to aspirate the cells into the needle shaft of fluid into the syringe
Can increase the risk of bleeding and cell damage, due to negative pressure
Commonly used for very firm and fluid filled masses
Describe the non-aspiration technique
A needle is used with NO SYRINGE attached
Used for sampling of very vascular masses - avoids blood contamination
Useful when sampling a precise location i.e. a small mass, thyroid gland
A core biopsy of the sample if effectively obtained, therefore, cellular structure is better maintained when compared to the FNA technique
Patients can be less apprehensive during sampling as equipment is minimal, not visualised and tissue damage is also reduced
Describe sample preparation for a smear
Sample should be rapidly transferred from the needle to a slide glass
Delay can lead to clotting within the needle shaft, trapped the sample in the shaft
Rest the needle onto the labelled slide and depress the plunger briskly, resulting in a droplet on the slide
Describe smear preparation
Squash method
Blood smear technique (feathered edge)
Line concentration technique
Star
Touch prep
Whichever used, must produce a mono-layer of cells to allow slide to be appropriately examined
Describe the squash method
Commonly most preferred as simplest to do
Excellent for semisolid materials and small volume samples
Sample is place onto microscope slide and second slide is used to transfer the sample and spread it across a second slide
Downwards pressure should be avoided
Describe the blood smear technique
Example same technique as used for blood smear, but often slower
Can result in cell damage
Describe the line concentration technique
Excellent for semisolid materials and small volume sample
Used for samples with suspected low cellularity i.e. fluid washes
Same technique as blood smear, but spreader slide is lifted from the sample slide when approx 2/3rds along the slide
The end of line formed by using this technique will contain a concentrated quantity of cells
Can cause damage and lysis of cells due to shearing action of the slide
Describe the star method
Aspiration needle is used to drag the material into radiating streaks from the central droplet
Minimally traumatic, but is relatively ineffective method of spreading the sample thinly
Often too thick for examination
Describe the twisting technique
Second slide is applied to the surface of the droplets, slides are twisted 90 degrees counter to each other before being lifted off
Slides stick together which can cause cell damage and a smear that is too thick to assess
Describe touch preparation/impression smear
Made from crusted or ulcerated skin lesions, bone marrow
Crusts should be removed and the area of interest blotted with a tissue
This area can be moistened with a sterile cotton bud soaked in 0.9% saline (from a drip bag) or squeezed to encourage natural exudate formation
Clean microscope slide is then firmly pressed onto the lesion and sample obtained
Bone marrow can be rolled between two slide to obtain a smear
Describe sample examination
Sample should be fully dried before attempting to stain (10-20 minutes)
Stain using ‘diff quick’ - do not stain if sending to external laboratory
Examine under the microscope using the power x10, high power x40 then oil immersion x100
Examine the presence of white blood cells, abnormal cell morphology, malignant cells
What are the advantages of vaginal cytology?
Cheap
Quick and easy
Minimally invasive and traumatic for the patient
Provides useful information to highlight timings for progesterone blood testing
Slides can be read in house if trained staff
What are the disadvantages of vaginal cytology?
Incorrect sampling can result in erroneous results
Training required to read slides correctly
Regular visits to the vets may be required
Positive result requires confirmation with progesterone blood test
Describe sampling technique for vaginal cytology
Ensure patient is suitable restrained on a table
Lips of vulva should be separated with gloved fingers and sterile cotton tip passed into dorsal aspect of the vulva
Advance the tip cranio-dorsally, towardsthe vertebral column and into the vagina. Tip should be moved into the vagina past the vestibule
Gently rotate the cotton tip within the vagina and withdraw
What are the different cell types?
Basal - Smallest and have large nucleus
Parabasal
Intermediate
Superficial/squamous cells
