haematology (done) Flashcards
why might we perform a haematology exam?
(6 marks)
- pre GA
- as screening test for systemic disease
- a diagnostic tool
- monitor disease progression
- monitor response to treatment
- to hgihlight subclinical disease
patient preperation for haematology exam?
(4 marks)
- fast patient 8-12hrs (not young pups) to avoid lipemic sample
- stress free patient for glucose estimation, therefore, provide a quiet + calm environment
- obtain samples prior to medicating / at least 5-10 days following final dose of medication
- some blood stim tests require food / meds to be adminsitered between blood sampling
what are the sampling sites?
(4 marks)
- jugular
- cephalic
- saphenous
- marginal ear vein
location of jugular vein?
(1 mark)
ventral surface of neck, running parallel either side of trachea
advantages of jugular sampling sites?
(3 mark)
- easily visualised in healthy animals, when the patient is correctly positioned
- reduced risk of haemolysis
- good blood flow
disadvantages of jugular vein sampling?
(1 mark)
sampling can be challenging in overweight animals
use of applying digital pressure to the sample site?
(1 marks)
prevent haematoma formation
location of cephalic vein?
(1 marks)
cranial aspect of both front forelimbs
advantages of cephalic vein?
(4 marks)
- moderately sized vein
- easy to visualise in healthy patients - if correctly raised
- can be used if jugular vein is not accessible
- good site for catheter placement
disadvantage of cephalic vein sampling?
(1 marks)
vein can collapse in small mammals
location of saphenous vein?
(3 marks)
lateral aspect of the hindlimbs, proximal to the hock, distal to the stifle
advantages of saphenous vein?
(3 marks)
- easy to see and visualise
- use if jugular and cephalic route are inaccessible (e.g. scarred - diabetic patients)
- useful for sampling agressive / nervous patients + rabbits
disadvantages of saphenous vein sampling?
(1 mark)
difficult to visualise in smaller and circulatory compromised patients
location of marginal ear vein?
(1 mark)
outer edge of ear surface
advantages of marginal ear vein sampling?
(1 mark)
use in rabbits for catheter placement and blood sampling
disadvantages of marginal ear vein sampling?
(2 marks)
- collpase of vein common when negative pressure applied = smaller vein
- bleeding can be slow + therefore, haemolysis of sample common
advantages of lateral tail vein sampling?
(2 marks)
- easily accessible
- most common catheter + blood sampling site in mice + rats
equipment for sample collection?
(8 marks)
- clippers / scissors
- blood tubes
- tape (catheter)
- chlorohex sol and surgical spirit
- swabs - used pre and post
- gloves
- approriate needle + syringe
- blood smear slides
blood tubes, their colour and what they test?
(15 marks)
- haematology - EDTA (lavender / pink / red)
- biochemistry - lithium heparium (orange)
- glucose estimation - fluroride ocalate (yellow / grey)
- coagulation tests - sodium citrate (green / lavender)
- courier / serum seperation) - serum gel (brown)
needle sizes?
(gauge of needle and colour)
(10 marks)
- 16G - white
- 18G - pink
- 19G - cream
- 20G - yellow
- 21G - green
- 22G - black
- 23G - blue
- 24G - medium purple
- 25G - orange
- 26G - brown
(16G largest, 26G smallest)
how do vacutainers work?
(2 mark)
draw blood from the vein via negative pressure into the container on the other side.
double edged needle.
use of vacutainers?
(1 mark)
in horses and large animals
(larger gauge needles so more suitable)
other sample considerations?
(3 marks)
- good environment to take sample: space and light
- comfortable for patient and sampler to take sample: table height, position
- restraint methods: towel, muzzle
restraint methods?
(2 marks)
- jugular - raise head, support body (dogs)/extend FL (cats)
- marginal ear vein - towel wrap body (rabbits)
steps for blood sample collection?
(6 marks)
- clip animal and clean area with chlorohexidine / surgical swab
- raise the vein (occlude)
- introduce needle and drawback (negative pressure)
- release vein
- remove needle when enough collected and apply pressure
- fill blood tubes
what happens if you overfill a blood tube?
(1 mark)
blood clot formation as insufficient anticoagulant
what happens if you underfill a blood tube?
(1 mark)
alter cell morphology causing crenation due to excessive amount of anticogaulant
what does EDTA contamination result in?
(2 marks)
erroneous hyperkalaemia (excess potassium) + hypocalcaemia (low calcium)
what do to with blood tubes with anticoagulant after collection?
(1 mark)
gently rotate sample bottle to mix sample and anticoagulant
what to do with serum blood tubes with no anticoagulant after collection?
(2 marks)
- do not invert
- place in vertical position and allow sample to settle and clot for approx 30-60mins
most common reasons there is lack of blood flow when sampling?
(in terms of injection technique)
(5 marks)
- bevel on vein upper wall doesnt allow blood floe
- bevel on vein lower wall doesnt allow blood flow
- needle inserted too far
- needle partially inserted and causes blood leakage into tissue
- collapse of vein
post venipuncture complications?
(8 marks)
- septicemia
- clipper rash
- oedema
- petechiae
- phlebitis
- haematoma
- thrombo-phlebitis
- thrombus
why is it important to sample, handle and store blood for analysis correctly?
(7 marks)
- haemolysis of sample
- inaccuracy of results
- re-sampling if sample destroyed
- expense
- delay in treatment
- increased anxiety for the client, leading to dissatisfaction
- inconvience for the client and practice staff
what is haemolysis?
(2 marks)
breakdown of the RBCs (cell lysis / burst)
the serum / plasma within a sample has a red discolouration caused by lysis of the cell and leakage of haemaglobin from damaged erythrocytes
what is increased by sample haemolysis?
(RBCs release what components into the plasma?)
(7 marks)
- phosphate
- potassium
- ALKP
- calcium
- albumin
- TP
- magnesium
how haemolysis affects the accuracy of a blood sample?
(1 mark)
as rate of haemolysis increases (as time goes on), the accuracy decreases
what is crenation?
(1 mark)
RBCs shrinks and turns ‘spikey’
when does crenation of sample occur?
(2 marks)
- in hypertonic solution
- old blood (RBCs dry out)
potential causes of blood sample haemolysis?
(11 marks)
- failure to seperate serum + RBCs prior to postage
- contact with water / surgical spirit
- ‘milking’ the sample, pumping the foot to increase blood flow
- failure to remove needle before ejecting blood into blood tube
- exposure to toxins
- excessive pressure on syringe plunger
- excessive time delay before testing
- vigourous shaking
- immune mediated erythrocyte destruction
- haemoparasites
- fine gauge needle
potential causes of a lipaemic sample?
(4 marks)
- patient not fasted prior to sampling, post prandial sample
- late stage pregnancy
- endocrine disorder - hypothyroidism, type II diabetes mellitus
- pancreatitis
what is an icteric sample?
(1 mark)
the prescence of high levels of pilirubin in plasma / serum - hyperbilirubinaemia
what colour is an icteric sample?
(1 mark)
range from dark amber to bright yellow
what does hyperbilirubinaemia cause?
(5 marks)
- decreased cholesterol
- triglyceride
- creatinine
- lipase
- total protein and levels
potential causes of an icteric sample?
(5 marks)
- biliary tract obstruction
- haemolysis - haemolytic anaemia, external haemorrhage
- ingestion of toxin
- haemoparasites
- hepatic dysfunction
what do blood smears show?
(1 mark)
cell morphology
storage of blood?
(4 marks)
- blood preserved in frige at 4-8 degrees C, for 12-24h
- alternatively, remove clotted serum with aseptic fine bore pipette and transfer to sterile vial - this can be stored at 4-8 degrees C for up to 7days
- serum can be stored frozen at -20 degrees C and transported on ice
- do not freeze whole blood