Blood Film Examination (Blood)

Testing Laboratory

Department

Haematology

Delphic Registration Code (Alpha Code)

CFLM

Test Code (Numeric Code)

1562

Laboratory Handling

Sample Stability

The peripheral blood film smear should ideally be prepared within 4 hours of collection. The blood film can be made up to 24 hours after collection if the FBC is stored at 4 degrees C, but artefactual changes may occur.

Associated Tests

• Full Blood Count (Blood)

Synonyms

Peripheral smear, Film, BF, Morphology, Manual DIFF

Turnaround Time

2 hours

45 minutes for Urgent Specimens

Specimen Type

• Whole Blood

Specimen Requirements

Tube/Container Type:

Preferred

• EDTA (Microtainer)
• EDTA (Lavender Cap)

Preferred Sample Volume (ml)

3

Minimum Sample Volume (ml)

0.3

Paediatric Specimen Requirements

Tube/Container Type:

Preferred

• EDTA (Microtainer)

Minimum Sample Volume (ml)

0.3

Additional Specimen Information

3 mL EDTA tube (lavender top)
Micro collect 300 µL blood in EDTA microtainer.
For neonate's minimum - 200 µL (but 300 µL needed if reticulocyte count required)

Test Method

All blood films are analysed through CellaVision. This is an automated microscope system that takes high resolution images of the blood cells and then identifies the various cell types using a neural network. These images are sent to monitors where they are verified or amended by Haematology staff. Some blood films may still be examined by microscope

Uncertainty of Measurement

Not Applicable

The full blood count results pass through a series of algorithms that take into account previous results and analyser flagging. A blood film is made if the results are significantly abnormal, flagged by the analyser or have changed significantly from previous results. Films are examined on all children under 180 days old and films on dialysis patients every 3 months unless there is a significant change.

The blood film examination includes a comment on red and/or white cell morphology and a scanned platelet estimate. In most cases the automated differential will be reported from the analyser but if there is a significant left shift or an abnormal white cell population then a 100 cell differential may come from CellaVision or be counted using the microscope.

Contact Information