Emergency Blood Transfusion in Unknown Rhesus Status
Group O RhD negative red blood cells are the blood group of choice for emergency transfusion when Rhesus status is unknown, with the critical exception that Group O RhD positive is acceptable for males, postmenopausal females, and adults without childbearing potential. 1
Blood Selection Algorithm by Patient Category
Women of Childbearing Potential (<50 years) and Children
- Always use Group O RhD negative blood 1, 2
- This prevents RhD alloimmunization and subsequent hemolytic disease of the fetus and newborn in future pregnancies 1
- Women who are RhD negative and receive RhD positive blood can develop immune anti-D antibodies, which cause severe fetal complications 1
Males and Postmenopausal Females
- Group O RhD positive blood is acceptable and preferred to conserve scarce RhD negative inventory 1
- This strategy reduces overdependence on Group O RhD negative stocks, which adversely impacts blood supply management 1
- The risk of anti-D alloimmunization in emergency patients receiving RhD positive blood is low (3-6%) 3
When Patient Sex is Unknown
- Default to Group O RhD negative blood 1
Transition to Group-Specific Blood
Switch to group-specific blood as soon as possible (typically within 10-15 minutes of laboratory receiving a properly labeled sample) 1
- Blood grouping can be performed in approximately 10 minutes, not including transport time 1
- Group-specific blood should be rapidly available within 15-20 minutes 1
- In massive bleeding, patients have minimal circulating antibodies and usually accept group-specific blood without reaction 1, 2
- Continuing universal donor blood unnecessarily wastes scarce Group O RhD negative resources 1
Critical Safety Considerations
Blood Sample Collection
- Send blood samples to the laboratory at the earliest possible opportunity for blood grouping, antibody screening, and compatibility testing 1
- Proper patient identification with four core identifiers (first name, last name, date of birth, patient identification number) is essential 1
Monitoring for Complications
- Most transfusion-related morbidity results from incorrect blood administration, not blood group incompatibility 1
- Antibodies may develop at a later stage if the patient survives, requiring follow-up antibody screening 1
- The risk of anti-D alloimmunization is significantly higher (26%) when known RhD negative patients receive RhD positive blood during shortages, compared to emergency patients with unknown blood type (4%) 3
Special Populations
- Premenopausal females whose blood group is unknown must receive O RhD negative cells to avoid sensitization 1
- One unit of RhD positive blood given to an RhD negative woman of childbearing age requires high-dose anti-D immunoglobulin mitigation 4
Practical Implementation
Major hemorrhage protocols should enable immediate release of blood components without prior hematologist approval 1, 2