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.
Blood groups, antibody screening and crossmatching
Essential points for quick revision.
2 min synopsisUK scopeSources checked 27 Aug 2026Clinical review pending
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Life-threatening bleeding before compatibility is complete
Transfusion must not be delayed for a full serological crossmatch when haemorrhage threatens life, but emergency release still requires positive identification, immediate sampling and direct laboratory communication.
Action: Activate the local major-haemorrhage pathway, take correctly labelled pre-transfusion samples before blood if this causes no delay, state urgency and special requirements to the laboratory and use approved emergency group O red cells. Move to ABO-compatible group-specific components as soon as a secure group is available and document emergency release.
Synopsis
Obtain a safe pre-transfusion sample, interpret ABO, RhD and antibody testing, select compatible components and manage urgent release without preventable delay or mismatch.
Positive patient identification and immediate labelling beside the patient are the most important pre-analytical safeguards; wrong blood in tube can make technically perfect testing lethal.
ABO grouping combines forward typing of red-cell A and B antigens with reverse typing of expected plasma antibodies; a discrepancy must be explained.
RhD typing guides D-compatible red-cell selection and prevention of anti-D alloimmunisation, especially for children and people with pregnancy potential.
Key red flags
Any discrepancy between the current ABO or RhD group, the historical record, the request and the patient's statement requires resolution before routine issue.
Investigation priorities
01
First-line: ABO and RhD groupFirst stepFirst line
Establish the major red-cell antigens that govern compatible component selection.
02
First-line: red-cell antibody screenFirst line
Detect unexpected antibodies capable of haemolysis or shortened donor-cell survival.
Management branches
Routine pre-transfusion requestIdentify, sample and define requirement
A patient may need red cells for anaemia, a procedure or anticipated bleeding.
Confirm indication, timing, component, number or dose, pregnancy and transfusion history, antibodies and special requirements.
Positively identify the patient and label the sample immediately beside them using one uninterrupted approved process.
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.