MLT

1. -Dr Sowmya Srinivas

2.  In investigating physiological function and
malfunction of blood, obtaining the specimen
is the first step towards analytic procedures.
 It is important to use appropriate blood
containers to avoid faults in specimen
collection, storage and transport to the
laboratory.
 Venous blood is generally used for most
haematological examinations and for
chemistry tests.

3.  Special care must be taken to avoid risk of
infection during all aspects of laboratory practice.
 The safety procedures must be followed as far
as possible when collecting blood.
 The operator should wear disposable plastic or
thin rubber gloves.
 It is also desirable to wear a protective apron or
gown, as well as glasses or goggles, if
necessary.

4. Care must be taken to prevent injuries,
especially when handling syringes,
needles and lancets.
Disposable sterilized syringes, needles
and lancets should be used if at all
possible, and they should never be re-
used.
Re-usable items must always be sterilized
after use

7. The constituents of blood may be altered
by several factors-
Pre-collection
Food or water intake within 2 hr
Smoking
Physical activity (including fast walking)
within 20 min
Stress
Drugs or dietary supplement administration
within 8 h.

8. During collection
Different times (diurnal variance)
Posture: lying, standing or sitting
Haemoconcentration from prolonged
tourniquet pressure
Excessive negative pressure when
drawing blood into syringe
Incorrect type of tube
Capillary versus venous blood.

9. Handling of specimen
Insufficient or excess anticoagulant
Inadequate mixing of blood with
anticoagulant
Error in patient and/or specimen
identification
Inadequate specimen storage conditions
Delay in transit to laboratory.

10.  Disposable Syringes and needles
 Tourniquet
 Specimen containers– plain and with various
anticoagulants
 Request form
 70% isopropanol swabs or 0.5% chlorhexidine
 Sterile gauze swabs or cellulose pads
 Adhesive dressings
 Rack to hold specimens upright during process
of filling
 A puncture-resistant disposal container should
also be available.

13. The needles should not be too fine, too
large, or too long, those of 19 or 21G are
suitable for most adults.
23G are suitable for children and ideally
should have a short shaft (about 15 mm).

15. The common containers for haematology
tests are available commercially with
dipotassium, tripotassium, or disodium
ethylenediaminetetra-acetic acid (EDTA)
as an anticoagulant.
And they are marked at a level to indicate
the correct amount of blood to be added.
Container with no additives are also used
when serum is required.

18. These are now in common use.
It consists of a glass or plastic
tube/container (with or without
anticoagulant) under defined vacuum, a
needle, and a needle holder which secures
the needle to the tube.

21. The cap can be pierced, so that it is not
necessary to remove it either to fill the
tube, or subsequently to withdraw samples
for analysis, thus minimizing the risk of
aerosol discharge of the contents.
The vacuum controls the amount of blood
which enters the tube.
Minimise the exposure to blood.

22. Blood is best withdrawn from an
antecubital vein or other visible veins in the
forearm.
It is recommended that the skin should be
cleaned with 70% alcohol (e.g.
isopropanol) or 0.5% chlorhexidine, and
allowed to dry spontaneously.

23.  The tourniquet should be applied just above
the venepuncture site and released as soon
as the blood begins to flow into the syringe or
evacuated tube.
 After cleaning and drying the site and
applying a tourniquet, ask the patient to make
a fist a few times.
 If a syringe is used for blood collection, the
piston of the syringe should be withdrawn
slowly and no attempt made to withdraw
blood faster than the vein is filling.
 Anticoagulated specimens must be mixed by
inverting the containers several times.

24. By using clean apparatus
Withdrawing the blood slowly
Not using too fine a needle, delivering the
blood gently into the receiver and avoiding
frothing during the withdrawal of the blood
Subsequent mixing with the anticoagulant.

25. The difference between plasma and serum
is that the latter lacks fibrinogen and some
of the coagulation factors.
Blood collected in order to obtain serum
should be delivered into sterile plain (non-
anticoagulant) tubes and allowed to clot
undisturbed for about 1 h at room
temperature.
Then loosen the clot gently from the
container wall.

26. The tubes are centrifuged for 10 min at
about 1200 rpm.
Pipette the supernatant serum into another
tube and centrifuge again for 10 min at
about 1200 rpm.
Transfer the supernatant serum to tubes
for tests or for storage.
For most tests, serum should be kept at
4C until used, but if testing is delayed,
serum can be stored at -20C for up to 3
months and at -40C or lower for long-term
storage.

29. European and American guidelines
recommend that the volume of whole
blood collected is between 450 and 500
mL ± 10%.
Blood is collected into an anticoagulant
comprised of citrate, phosphate and
dextrose designed to prevent blood from
clotting and maintain cellular function
during storage.

30.  The initial storage temperature of whole blood
determines which components can be
produced from it.
 Because platelet function rapidly deteriorates
at 4°C, whole blood must be processed on
the day of blood collection or stored overnight
at 22°C for platelet production.
 However, for the production of red cells,
whole blood can be stored at 4°C for 48-72
hours prior to separation

32. By using Anticoagulants like-
EDTA
Sodium citrate
Heparin
Acid-citrate dextrose(ACD), Citrate-
phosphate dextrose (CPD) or Alsever’s
solution – for long term preservation of red
cells.

33. Routine blood storage is 42 days or 6
weeks for stored packed red blood cells
Platelets may only be stored for 7 days,
due largely to their greater potential for
contamination, which is in turn due largely
to a higher storage temperature.

34. Red cells Leucocyte depleted:
Shelf-life - 42 days with the appropriate
additives
Storage temperature range - 2–6 ºC
Fresh Frozen Plasma:
Shelf-life -12 months
Storage temperature range - At –25 ºC or
below

35. Cryodepleted Plasma Precipitate:
Shelf-life -12 months
Storage temperature range - At –25 ºC or
below
Platelets:
Shelf-life - 5 days
Storage temperature range - 20–24 ºC

36. THANK YOU