Definition

Noun: A person whose blood is type O Rh-negative. This specific blood type is considered medically safe to transfuse into individuals with other blood types in emergency situations when the recipient's exact blood type is unknown or unavailable.

Usage

The term is used specifically in medical contexts, particularly in blood banking, transfusion medicine, and emergency care, to identify a donor whose red blood cells lack the A, B, and Rh(D) antigens.

Examples

• In a major accident, the hospital urgently called for universal donors to help the injured patients.
• Because she is a universal donor, she makes a point to donate blood regularly.
• The blood bank's supply from universal donors is critically low.

Advanced Usage

• The concept relies on antigen-antibody compatibility. Type O negative red blood cells do not have A, B, or Rh antigens, minimizing the risk of a dangerous hemolytic transfusion reaction in a recipient of any ABO and Rh type.
• While "universal donor" typically refers to red blood cells (type O negative), the term can sometimes be contextually applied to plasma donors with type AB blood, which lacks anti-A and anti-B antibodies. This is often specified as "universal plasma donor."

Variants and Related Words

• Universal donor blood: The actual blood product from a universal donor.
  • The ambulance carries units of universal donor blood.
• O-negative (O-): The common shorthand for the blood type.
  • Her medical bracelet indicates she is O-negative.

Synonyms

• O-negative donor (more precise clinical term).
• Type O Rh-negative donor.

Notes

• "Universal donor" is a functional label based on current medical science and transfusion protocols. It indicates a high degree of compatibility, not absolute universality, as other rare blood group factors must still be cross-matched for safety in non-emergency settings.
• The recipient's body will produce antibodies against the O-negative cells if they are a different type, but this reaction is typically less immediate and severe than the reverse scenario, allowing time for stabilization.

Noun

1. a person whose type O Rh-negative blood may be safely transfused into persons with other blood types