Peripheral Blood Smear (Blood Film)
Also known as: Blood film, PBS, Peripheral film, PBS test, blood smear test
A drop of blood is spread on a glass slide, stained and examined under a microscope by a laboratory scientist or haematologist. It shows the shape and size of red cells, the types of white cells, and platelets.
Why it's ordered
When the CBC is abnormal, to find the type of anaemia, to look for abnormal or immature cells (for example in leukaemia), to check platelet clumps, and to look for malaria parasites.
Preparation
No preparation needed. It is usually made from the same blood sample as the CBC.
Typical adult values
| Normal report | Red cells normal in size and colour (normocytic, normochromic), normal white cells, adequate platelets, no parasites |
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Ranges vary between labs and methods. Always use the range printed on your report.
If the report shows abnormal findings
Findings such as small pale red cells (microcytic hypochromic), large red cells, target cells, sickle cells, immature white cells (blasts) or parasites point your doctor towards a cause. Blasts on a smear need urgent specialist review.
Good to know
The smear adds detail the analyser cannot give, but it is interpreted together with the CBC and your symptoms. Report wording varies between labs; ask your doctor to explain any finding.
Common questions
Why is a blood smear done after a CBC?
When the CBC is abnormal, to find the type of anaemia, to look for abnormal or immature cells, to check platelet clumps, and to look for malaria parasites.
What does microcytic hypochromic mean?
Small pale red cells. It points your doctor towards a cause such as iron deficiency or thalassaemia trait.
What does a normal smear report say?
Red cells normal in size and colour (normocytic, normochromic), normal white cells, adequate platelets and no parasites.
Are blasts on a smear serious?
Blasts on a smear need urgent specialist review.