Routine Haematology

The Routine Haematology Profile (also called the Full Blood Count (FBC) or Full Blood Examination (FBE)) consists of a qualitative and quantitative study of the patients blood sample.

Qualitative

This aspect of the FBC examines the morphology of the red cells, white cells and platelets.

Quantitative

This portion of the examination looks at the approximate white cell count (WCC), platelet count and at a differential white cell count.
Other tests which can provide important information to the scientist include the reticulocyte count, the detection of Heinz bodies and sometimes, the Erythrocyte Sedimentation Rate (ESR).

Specimen

The forms of blood collected from the patient include whole blood, clotted blood and capillary blood. This blood is, under most circumstances venous, and can be taken from the:

Cubital Fossa
Back of the hand
Ankle
Femoral vein
Jugular

  A syringe and needle is the most common way to take a blood specimen from a patient (the use of butterfly clips allows large volumes to be removed more easily).   The bore/diameter of a needle is called its "gauge".

  The higher the number, the smaller the bore eg. a 12 gauge needle is larger than a 26 gauge needle. A method requiring less handling of the syringe and which withdraws a measured amount of blood relies on a sterile evacuated tube. The vein is first punctured by a double ended sterile needle, a tube is pushed over the exposed needle and the vacuum withdraws a fixed amount of blood from the vein (usually 10mL). This method is not recommended for young children, the elderly (due to reduced blood pressure) or burns patients (veins can be difficult to find).

  Capillary blood collection is useful for patients requiring multiple transfusions, burns patients, arthritics, babies (from the heel) and for verification of a previous specimen. The area must be warm to prevent an increase in RCC, Hb and WCC and because the flow will be too slow if the body is cold as these vessels are not under as much pressure as arterial blood or a vein with a tourniquet. The first drop of blood after puncturing the skin (usually with a sterile lancet) is removed to prevent dilution of the specimen due to the presence of tissue fluid. This method provides about 200 microlitres of blood.

Sources Of Error

Patient Identification
Equipment Failure
Haemodilution
Haemoconcentration (eg. due to a tourniquet being applied for to long)
Haemolysis (eg. trauma to RBC, alcohol)
Clotting
Inadequate Labelling
Mixing of Specimen

Glossary

Hb
Haemoglobin. This abbreviation is commonly used to represent the concentration of haemoglobin in blood.

RCC
Red Cell Count. This abbreviation usually refers to the total number of red cells (erythrocytes) in whole blood (million/mL)
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