Cytology

Question 1

Define cytology

Answer 1

The medical and scientific study of cells

Question 2

What are the benefits of cytological analysis?

Answer 2

Relatively inexpensive

Identification inflammatory cells

Can be quick and easy

Identification of stages of reproduction

Identification of pathogenic cells

Identification of neoplastic cells

Question 3

Give examples of cytology samples

Answer 3

Bone marrow

Synovial fluid - joint tap

Cerebral spinal fluid - LP

Neoplasia - FNA

Question 4

How do we obtain a sample?

Answer 4

Fluid aspiration

Scrapes

Fine needle aspiration

Impression smear

Fine needle - non aspiration

Swabs

Question 5

CSF cells degrade rapidly. In what time scale from sampling should they be analysed?

Answer 5

30-60 minutes

Question 6

When might an FNA be used?

Answer 6

Neoplasia

Inflammatory mas

Abscess

Lymph node

Question 7

What are the advantages of FNA?

Answer 7

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

Question 8

What gauge needle should be used for an FNA?

Answer 8

Less than 20g

Question 9

How quickly should the sample be analysed?

Answer 9

Within 5-10 minutes to prevent degradation of sample

Question 10

Describe the aspiration technique

Answer 10

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

Question 11

Describe the non-aspiration technique

Answer 11

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

Question 12

Describe sample preparation for a smear

Answer 12

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

Question 13

Describe smear preparation

Answer 13

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

Question 14

Describe the squash method

Answer 14

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

Question 15

Describe the blood smear technique

Answer 15

Example same technique as used for blood smear, but often slower

Can result in cell damage

Question 16

Describe the line concentration technique

Answer 16

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

Question 17

Describe the star method

Answer 17

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

Question 18

Describe the twisting technique

Answer 18

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

Question 19

Describe touch preparation/impression smear

Answer 19

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

Question 20

Describe sample examination

Answer 20

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

Question 21

What are the advantages of vaginal cytology?

Answer 21

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

Question 22

What are the disadvantages of vaginal cytology?

Answer 22

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

Question 23

Describe sampling technique for vaginal cytology

Answer 23

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

Question 24

What are the different cell types?

Answer 24

Basal - Smallest and have large nucleus
Parabasal
Intermediate
Superficial/squamous cells

Question 25

Describe parabasal cells

Answer 25

Non-cornified cell - indicate anoestrus, early pro-oestrus and diooestrus

Not present in oestrus

Question 26

Describe intermediate cells

Answer 26

Non-cornified cells that differ in size with a prominent nucleus. 2-3 times the size of a normal basal cell

Present at all stages of oestrus cycle apart from during oestrus

Question 27

Describe superficial cells

Answer 27

Cornified cells - very large, flat, polygonal cells with an absent or small and faint nucleus

Not commonly seen during an or dioestrus an increase in prevalance during pro-oestrus

Large numbers indicate oestrus i.e. bitch is ready for mating