Educational draft · awaiting clinical reviewUse Rapid for revision, not patient-care decisions. Check current national and local guidance and the BNF or BNFC before acting.
2 min synopsisUK scopeSources checked 27 Aug 2026Clinical review pending
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Critical anaemia or major haemorrhage
A haemoglobin threshold designed for stable, non-bleeding adults must not delay blood in life-threatening haemorrhage, profound symptomatic anaemia or threatened tissue oxygenation.
Action: Assess ABCDE, control bleeding and activate the major-haemorrhage pathway when indicated. Send urgent group, screen, full blood count, coagulation and blood gas samples without delaying emergency red cells. In non-haemorrhagic critical anaemia, involve senior and transfusion specialists, give the minimum red-cell dose needed, treat the cause and reassess clinically after each unit.
Synopsis
Decide when red-cell transfusion is justified, apply UK restrictive thresholds safely, prescribe an appropriate dose and reassess benefit while treating the cause of anaemia.
Red cells improve oxygen-carrying capacity; they do not replace iron, stop haemorrhage or treat the mechanism causing anaemia.
First-line decision-making combines haemoglobin, symptoms, bleeding trajectory, cardiopulmonary reserve and the likelihood that a reversible cause can be treated safely without transfusion.
For stable adults without major haemorrhage, acute coronary syndrome or a chronic transfusion programme, NICE recommends a restrictive threshold of 70 g/L and a post-transfusion target of 70–90 g/L.
Key red flags
Active major haemorrhage, haemodynamic instability or ongoing rapid blood loss invalidates routine restrictive-threshold algorithms and requires a haemorrhage protocol.
Investigation priorities
01
First-line: full blood count and trendFirst stepFirst line
Confirm anaemia, define indices and establish rate of change.
02
First-line: clinical oxygen-delivery assessmentFirst line
Determine whether anaemia is causing current physiological compromise.
Management branches
Stable non-bleeding anaemiaUse a restrictive, one-unit strategy
Haemoglobin approaches 70 g/L without major haemorrhage, ACS or a chronic programme.
Assess symptoms, trajectory, reserve, reversible cause and patient preference rather than transfusing automatically.
If transfusion is justified, prescribe one appropriately selected unit at a safe rate with consent and baseline observations.
Treatable deficiencyCorrect the cause and reserve blood for urgency
Iron, vitamin B12 or folate deficiency explains stable anaemia.
National guidance is shown before implementation-dependent detail. Typical adult dose examples remain subject to patient factors, contraindications and the live BNF or specialist protocol. Source check completed 27 Aug 2026; clinical approval remains outstanding.
NICE NG24: red blood cell transfusionCurrent UK restrictive thresholds, ACS target, chronic-programme individualisation and single-unit reassessment.