Synopsis
Interpret every full-blood-count lineage in clinical context, recognise dangerous patterns and artefacts, and move from an abnormal number to a proportionate confirmatory and referral plan.
- Read haemoglobin, white-cell differential and platelets together before focusing on a flagged value; abnormalities across several lineages suggest marrow, infiltrative, consumptive or systemic disease rather than an isolated deficiency.
- Compare with the patient's baseline and the laboratory's age-, sex- and pregnancy-appropriate reference interval. Direction and speed of change often carry more clinical information than a single result just outside range.
- For anaemia, begin with mean cell volume, mean cell haemoglobin, red-cell distribution width and reticulocytes, then integrate film, iron studies, B12, folate, renal, inflammatory and haemolysis testing as the phenotype directs.
Key red flags
Anaemia plus neutropenia and thrombocytopenia raises marrow failure, infiltration, acute leukaemia, severe deficiency, sepsis, hypersplenism or treatment toxicity. Fever, bleeding or blasts makes the pattern urgent.
Investigation priorities
Confirm an unexpected abnormality and establish its trajectory across all lineages.
Management branches
The patient is unwell, bleeding or febrile, or the report shows blasts, severe cytopenia, fragmentation or a critical laboratory alert.
- Assess ABCDE, confirm symptoms and observations, inspect for bleeding or infection, obtain urgent repeat and film samples where this causes no harmful delay, and contact senior haematology.
- Use the supported emergency pathway: preferred management is immediate neutropenic-sepsis treatment for fever with significant neutropenia, a TTP pathway for microangiopathic haemolysis, or an acute-leukaemia pathway for blasts or abnormal promyelocytes.