Introduction
- Vital to successful biochemistry and hematology.
- Good technique essential.
- Jugular vein preferable
rapid, unobstructed flow of blood. - Peripheral veins, eg cephalic and saphenous, often detrimental → slow blood flow → sample artifacts (hemolysis and microclots).
Uses
- Biochemistry/hematology.
Advantages
- Simple technique (unless difficult animal).
Requirements
Materials required
Minimum consumables
- Needles: 18-21 gauge/1 inch.
Either Syringe: 2.5-20 ml.
Or Evacuated tubes: 2-3 ml. - For sample tube preference see
.
Sequelae
Reasons for treatment failure
- Repeated entry into same site with same needle → introduce tissue proteins → abnormal results.
Hemolysis
- Use of too fine a needle.
- Failure to remove needle from syringe prior to placing blood in tube.
- Needle pushed directly through evacuated tube top. Fluid flow under pressure inevitably damages the red blood cells. Hence remove bung and gently release blood from syringe.
- Excessive back pressure when withdrawing blood.
Biochemical artifacts
- Posting samples (time related)
- Minimize by separating serum/plasma from clot or heparinized samples before sending sample.
Difficulty in extracting sample
- Obesity .
- Excess skin folds.
- Excess back pressure.
