Blood typing is a laboratory result. Do not choose blood for a transfusion from an online chart or a person’s recollection of their blood group.
Understanding the basics
The ABO system uses A, B, AB and O groups; Rh status is commonly shown as positive or negative. Compatibility depends on the blood component and clinical circumstances. A treating team and laboratory must make the necessary checks.
If blood is needed
- Contact the treating hospital’s blood bank and follow its instructions.
- Ask which component is needed and what information a potential donor should bring.
- Use a regulated blood service; donations require appropriate screening and testing.
- Do not publish a patient’s private records or a donor’s identity in a public directory.
This page provides general reference information and does not determine donor eligibility or transfusion suitability.