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.
- A group and antibody screen establishes ABO, RhD and unexpected red-cell antibodies but does not by itself reserve units for the patient.
- A crossmatch confirms that selected donor red cells are compatible by validated electronic issue or a serological indirect antiglobulin method, depending on antibody history and local rules.
- First-line routine issue is ABO-compatible, RhD-appropriate red cells that lack the antigen corresponding to every current or historical clinically significant antibody.
- A second independently collected group sample is commonly required before electronic issue or ABO-identical blood when no secure historical group exists; never split one venepuncture into two samples.
- Samples from patients transfused or pregnant within the preceding three months are generally valid for no longer than 72 hours because new antibodies can emerge.
- Electronic issue is safe only when the laboratory system, current sample, two-group rule and antibody criteria are all validated; it is not a less rigorous crossmatch.
- Emergency group O selection follows local stock-conservation policy: D-negative units are prioritised for children and females with pregnancy potential, while D-positive units may be used for eligible adults.
- Switch from emergency group O to compatible group-specific red cells promptly once the laboratory authorises it, preventing avoidable depletion of scarce O D-negative stock.
- Record every antibody and special requirement permanently, give the patient an antibody card where appropriate and communicate across hospitals and pregnancies.
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.
A sample labelled away from the patient, pre-labelled tube, missing identifier or label completed by someone who did not take the sample is unsafe and should be rejected.
A positive antibody screen, previous clinically significant antibody, transfusion or pregnancy history can require identification and antigen-negative units and may substantially delay issue.
Anti-CD38 or anti-CD47 treatment can interfere with serological compatibility testing; the laboratory must know the medicine and treatment dates before urgent blood is needed.
Uncrossmatched blood does not mean unchecked blood: identity, component label, expiry, integrity, prescription and emergency allocation must still be verified at collection and bedside.
Investigation priorities
Establish the major red-cell antigens that govern compatible component selection.
Detect unexpected antibodies capable of haemolysis or shortened donor-cell survival.
Management branches
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.
- Send the clinical details and required time to the laboratory; review group, screen, sample expiry and unit availability before the planned event.
Circulatory compromise means waiting for routine compatibility would endanger life.
- Activate the major-haemorrhage protocol, call the laboratory and obtain a correctly labelled sample without delaying resuscitation.
- Use locally designated emergency group O red cells with D selection based on age, sex, pregnancy potential and stock policy.
- Change to compatible group-specific and then fully crossmatched antigen-appropriate units as soon as laboratory testing permits.