Full Blood Count (FBC)

Department of Haematology

Notes

• Full blood counts are performed on automated equipment and provide haemoglobin concentration, red cell indices, white cell count (with a differential count) and platelet count.
• The presence of abnormal white cell and red cell morphology is flagged by the analysers.
• Blood films may be inspected to confirm and interpret abnormalities identified by the cell counter, or to look for certain specific haematological abnormalities.
• Although it may be possible to action an add on request for a blood film on an existing FBC sample, “in-vitro degeneration” may adversely affect interpretation of the blood film. An assessment will be made regarding the blood film quality on an individual basis. Please indicate the reason for the add on blood film.
• Grossly abnormal FBC results and abnormal blood films will be phoned through to the requestor.
• There is no need to request a blood film to obtain a differential white count. It is, however, important that clinical details are provided to allow the laboratory to decide whether a blood film, in addition to the automated analysis, is required.
• Under some circumstances a differential is not routinely performed, e.g. pre-op, post-op, antenatal and postnatal requests.
• Full Blood Counts are performed at CGH and GRH
• See also: Reticulocyte Count

The FBC comprises the following tests

Standard

• Haemoglobin (Hb)
• White Blood Count (WBC)
• Platelet Count (Plt)
• Red Cell Count (RBC)
• Haematocrit (HCT)
• Mean Cell Volume - Red cell (MCV)
• Mean Cell Haemoglobin (MCH)

Differential White Cell Count (where applicable)

• Neutrophils
• Lymphocytes
• Monocytes
• Eosinophils
• Basophils

And if appropriate

• Blood Film

Sample Requirements

2ml or 4ml EDTA sample or a Paediatric 1ml EDTA sample.

Sample Storage and Retention

• Pre analysis storage: do not store, send to laboratory within 4 hours.
• Sample retention by lab: EDTA samples are retained for a minimum of 48 hours at 2-8°C
• Transport of samples may affect sample viability, i.e. FBC results will degenerate if exposed to high temperatures, such as prolonged transportation in a hot car in summer.

This test can be added on to a previous request as long as there is sufficient sample remaining and the sample is less than 24 hours old.

Turnaround Times

• Clinical emergency: 30 mins
• Other urgent sample: 60 mins
• Routine: within 2 hours
• We aim to examine blood films within 1 working day from sample receipt, however actual turnaround time will vary depending on clinical urgency.

Reference Ranges

If references ranges are required for paediatric patients please contact the laboratory for these.