Deciding when to use universal blood.

The O rhesus (RhD)-negative blood group can be transfused to any non-immunised patients. For this reason, O RhD-negative red cells, often called 'flying squad' blood or units, can be used in emergencies where patient blood group is unknown and, in extreme instances, where group-specific stock is unavailable. However, frequent and inappropriate use of this important blood group can prevent NHS Blood and Transplant and hospitals from providing it to patients who need it. This article provides an overview of blood groups, guidance on the appropriate use of O RhD negative blood and suggestions on how it can be used in emergency care practice.