• All of haematology analysis is performed on blood or bone marrow.
• The phlebotomist will use a torniquet and will do the sample by a technique called venepuncture, the blood is taken from the vein.
• Blood clots really quickly so within two to five minutes it would form a clot and a flui...
What happens to the sample before it gets to the lab and during lab that can affect the lab
results?
All of haematology analysis is performed on blood or bone marrow.
The phlebotomist will use a torniquet and will do the sample by a technique called
venepuncture, the blood is taken from the vein.
Blood clots really quickly so within two to five minutes it would form a clot and a fluid so in
order to analyse the cells and proteins we need to make sure that blood is not clotting, and
we do this via anticoagulants.
Each tube has got different anticoagulant embedded on the inside of it.
Once the blood has been taken and sent in the lab there's lots of different things that we can
look at.
RBCs make up 45% of the blood and their primary function is to carry oxygen and remove
carbon dioxide.
Platelets are the smallest of our cells, and they form clots, stop bleeding and they make up
approximately 1% of the blood.
Next, we've got our white blood cells and they fight bacteria and viruses, and they also make
up less than 1% of blood.
The remaining is 55% plasma which contains your proteins, ions, water, nutrients and gases.
In plasma there will be no clot formation.
Serum will not have any of the clotting factors that are involved in the cascade, and it won't
contain things like fibrinogen either.
Plasma is going to have all your blood cells and it has been treated with anti-coagulants,
serum is what remains after your blood has clotted.
Serum is really valuable as well and if you've ever had a vitamin B12 or an iron test that is
conducted on serum.
What happens when you go to your GP surgery and how do we actually get to the test being
in the laboratory.
A patient will go to the GP and then present with certain symptoms and then the GP will
interpret that and they will request blood tests or swab samples based on what the patient
is experiencing, the patient will then go to the phlebotomist or the nurse and the sample will
be collected, it will be transported to the laboratory where it will be prepared by medical
laboratory assistants, the biomedical scientists will analyse the sample, after the testing has
been completed the senior biomedical scientist or head BMS will then relay the results back
to the GP.
In this cycle there is so much scope for things to go wrong and 70% of the errors that occur
in the laboratory are due to pre analytical factors.
Do they need to fast or is it a non-fasting blood test?
Medication – e.g. carbamazepine which is a medication that is used to control certain types
of seizures so it's often given to people with epilepsy, mania or patients are suffering with
bipolar and it reduces abnormal electrical activity in the brain however a side effect of this
medication is it may decrease the number of blood cells are produced in the body so it's
, 2. Haematology Techniques and Methods
important patients tell their doctors if they've ever had bone marrow depression (decrease
number of blood cells) or any other blood disorders that were caused by the medication.
Do they need to avoid certain foods for example?
Protection form light – particularly important for samples that are taken for the dry blood
spots dried onto filter paper and are individually wrapped in foil or plastic and that stops
them from being cross contaminated, they also need to be stored away from sunlight so
they are usually put into a plastic bag to protect them from dust and moisture, although
these samples don't need to be refrigerated whilst they are being transported to the lab
they need to be stored in a cool place so they can analysed as quickly as possible so some
samples do need to be sent on ice to the lab.
The phlebotomist has a really important role in selecting the correct tube.
Which order do they take the sample in to ensure that they are reducing contamination?
Biochemistry, haematology, micro and immunology are the labs are make-up pathology and
approximately 400 tests are requested so you can see why errors can be made especially
when a lot of the tests are closely related.
Particularly in case of twins – initially when they are born, they have not been named they
would just call them twin 1 and 2 so they will have similar names and date of birth and it
gets very easily mixed up when it goes to the lab.
We don't want to be sending false results out because it affects the patient.
Sitting or lying down – is actually really important because blood volume decrease when
standing and it increases lying down by 6.5% in the serum concentration of proteins
enzymes and lipid.
Where it is taken from can also contaminate the sample.
These are all important things that are considered during the phlebotomy.
Need to know the names of the reagents that are added into them.
Your blood vessels will constrict and then a platelet plug will form to stop the blood from
pouring out. This step requires calcium.
Then the clotting cascade is activated and again calcium is a key component of that.
Finally, a clot forms and then you'll have your platelets and fibrinogen that form part of that
clot.
Calcium becomes very important when we start talking about the different tubes that are
used to collect blood.
2
Used for collecting whole blood.
It can be potassium or sodium EDTA (ethylenediaminetetraacetic acid) which binds calcium
and blocks the clotting cascade.
Calcium is an essential component of coagulation, so this tube is your basic haematology
tube, and it is used identifying and counting cells and also blood typing so the full blood
count, blood groups, sickle cell screen, malaria and HbA1c.
Plasma stored from EDTA can also be used to measure most proteins and genetic material,
calcium is necessary for a wide range of enzymatic reactions that occur within the
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