Dr Anupam Singh

SAMPLE COLLECTION

&ANTICOAGULANTS

MODERATOR--PROF ASHUTOSH KUMAR

•The procedure in which an operator bleeds a specific amount of blood of subject for a particular investigation can be termed as collection of blood.

Common examinations done on Blood are ???

1.Hematological2.Biochemical3.Serological4.Cultural5.Molecular

Samples can be collected from-1. Veins- most commonly used.

2. Capillaries3. Arteries- in case of arterial blood gas

analysis and paediatric patients

Venepuncture is a routine procedure . In order to do this safely the phlebotomist must have a basic understanding of the following:

1. Anatomy & physiology

2. Criteria for choosing a vein

3. The device to use4. Skin preparation5. Personal safety

PHLEBOTOMY TRAY---1. Syringes & needles2. Tourniquet3. Specimen containers4. Request form5. 70% isopropanol swabs6. Sterile gauze swabs7. Adhesive dressings8. Self sealing plastic bags9. Rack to hold specimens upright10. Puncture resistant disposal container

VenipunctureProcedure

1. Prepare the accession order.

2. Approach and identify the patient; sanitize hands.

3. Verify patient diet and latex sensitivity.

4. Assemble supplies.

5. Position patient.

6. Apply tourniquet.

7. Put on gloves.

8. Cleanse venipuncture site.

contd……

9. Perform venipuncture.

10. Order of draw.

11. Release the tourniquet.

12. Place the gauze pad.

13. Remove and dispose of the needle.

14. Bandage the arm.

15. Label blood collection tubes and record time of collection.

16. Send blood collection tubes to proper laboratories.

Capillary blood-

• To draw only a small amount of bloodin a microtubeor strip for blood sugar and bleeding time tests.

• For infants and young children.

Why the finger should not be Squeezed while collecting blood By finger prick method ?

Prick should be deep enough for free flow of blood or gentle squeezing to start the flow of blood . Squeezing the finger tip hard results in tissue fluids diluting the blood , thus lowering the hematological values.

Why initial 1-2 drops of blood are discarded in finger prick method ?

Initial drops of the blood gets contaminated withthe antiseptic and therefore discarded.

Why is ring finger preferred For capillary blood collection ?

Ulnar side of the tip of ring finger is comparatively less innervated andtherefore prick is less painful.

Reasons to reject specimen for Hematology are :

A.Clotted specimenB.Severely hemolyzed specimen C.Improperly labeled or unlabeled specimenD.Specimen too oldE.Failure to meet volume criteriaF.Improperly collected capillary specimenG.Leaking tubeH.Delay in transportI. Collection of specimen in wrong tube

complications Encountered inBlood collection

EcchymosisSyncopeHaematomaFailure to draw bloodPetechiaeEdemaObesityIntravenous therapyHemoconcentrationHemolysisBurned, damaged, scarred, and occluded veinsSeizures and tremorsAllergiesInability to obtain a blood specimen

What gauze needle should beused for collection of venous blood ?

•The needles of 19 or 21 G are suitable for most adults.

• 23G are suitable for children and ideallyshould have a short shaft.

Order of collection of specimen---

A.Blood culture or sterile tubes (i.e. yellow stopper)

B. Coagulation tube (light blue stopper)

C. Serum tube with or without clot activator or gel(red, gold or red-gray marbled stopper)

D. Heparin tubes(green or light green stopper)

E. EDTA tubes (lavender stopper)

F. Oxalate/fluoride tubes (gray stopper)

ANTICOAGULANT TUBE

EDTA (ETHYLENE DIAMINE TETRA-ACETATE)

•Types: sodium and dipotassium EDTA (1.50-2.2 mg/ml)

•Acts by its chelating effect on the calcium molecules in blood

•Suitable for routine hematological work such as CBC, HbA1c

•Repeated inversions of the container the anticoagulant is thoroughly mixed in the blood added to it.

For handling, transfer and storage of blood samples the following equipment is needed: 1. transfer and storage tubes (note that some of these should be freezable)2. disposable pipettes or pipettes with changeable apex3. centrifuge. If gel tubes are used, centrifuge should have swinging bucket rotor4. timer5. racks for tubes6. special boxes for tube transfer and storage7. set of labels with identification codes or other method to mark the tubes (note that these should not be vulnerable to freezing)refrigerator8. freezer (as required)

Effects of storage on blood count-

oVarious changes occur in anticoagulant blood when stored at room temp and these changes occur more rapidly at higher ambient temp.

oRed cell count, white cell count, platelet count & red cell indices are usually stable for 8 h after blood collection.

oWhen blood is kept at 4 deg c the effects on blood count are notusually significant for upto 24 h.

oBest to count TLC & platelets within 24 h and it should be notedthat the fall in TLC may become marked within a few hour, especiallyif there is an excessive amount of EDTA.

oRet count are unchanged when blood is kept in either EDTA or ACDanticoagulant for 24 h at 4 deg c but at room temp count begin to fall within 6 h.

oHb conc remain unchanged for days.

contd….

oCoagulation tests be carried out within 2 h when blood or plasmastored at 22-24 deg c, 4 h at 4 deg c, 2 week at -20 deg c, 6 M at -70 deg c.

oInappropriate handling of blood specimen during transfer to the laboratory may cause hemolysis, partial coagulation & cell

disintegration.

Effects of storage on blood cell morphology-

oOccurs within few hours of colletion. These changes may be discernibleby 3 h & by 12-18 h these become striking.

oSome but not all neutrophils affected, nuclear lobes may become separated. Small vacuoles appear in cytoplasm.

oIn monocytes, some or many devlop marked changes. Small vacuolesappear in cytoplasm. Nucleus undergoes irregular lobulation.

oIn lymphocytes, similar changes occur.

oNormal red cells get little affected upto 6 h at room temp but longerperiods lead to progressive crenation & sphering.