Glossary term · Tests & reports
Blood group and cross-match (also: Blood typing, Group and cross-match, Crossmatching): Blood grouping identifies a person’s ABO group and Rh factor; cross-matching tests donor blood against the patient’s blood before transfusion.
Blood grouping finds your ABO blood group and Rh factor. Cross-matching then checks that a specific unit of donor blood is compatible with yours. MedlinePlus explains that typing alone does not detect many minor antigens, so a reaction is still possible. Cross-matching is done before transfusions, except in emergencies. Hospitals arrange both before operations where blood may be needed.
What are the blood groups?
The four major ABO groups are A, B, AB and O. Your blood is also Rh-positive or Rh-negative. MedlinePlus notes that Rh-negative people can only receive Rh-negative blood.
How is blood typing done?
- ABO typing: your blood is mixed with antibodies against types A and B.
- Back typing: your serum is mixed with known type A and type B cells.
- Rh typing: a similar method checks the Rh factor.
- No special preparation is needed.
What does cross-matching add?
Many minor antigens are not detected during routine typing. A cross-match followed by a Coombs test can help detect them. This lowers the risk of an immune reaction against donated red cells.
Why does it matter for medical travellers?
Some operations, such as heart surgery or transplants, may need blood. Ask the hospital how blood is arranged and whether your attendant has any role. Rules on blood donation vary, so follow the hospital’s guidance.
Your blood group card
Carry a note of your blood group if you have one, but expect the hospital to retest. Hospitals rely on their own laboratory before any transfusion.
Questions people ask
Why test my blood group again if I already know it?
Hospitals confirm the blood group in their own laboratory before any transfusion. A record from elsewhere is useful background but is not used alone. Cross-matching is then done against the specific donor unit.
Does blood group matter for an organ transplant?
Blood group compatibility is part of transplant assessment, along with tissue typing such as HLA tests. The transplant team explains which tests the donor and recipient need and where they should be done.
Sources
General information, not medical or legal advice. Rules change: confirm with the official source. Your treating specialist decides on suitability, treatment and length of stay. How we write and check.