Blood Type Testing in the Outpatient Setting
To determine your blood type in an outpatient setting, order an "ABO and Rh typing" test, which is the standard blood group determination that identifies your ABO blood group (A, B, AB, or O) and Rh status (positive or negative). 1
Standard Test Order
- Order "ABO and Rh typing" as the basic test to determine blood type in the outpatient setting 1, 2
- This test identifies both the ABO blood group system (A, B, AB, or O) and the Rh blood group system (positive or negative), which are the two most clinically important blood group systems 2
- The test is performed using serological methods based on hemagglutination reactions with RBC antigens against specific antibodies 2
When Extended Testing Is Needed
For patients with specific clinical conditions, you should order more comprehensive testing beyond basic ABO/Rh:
- For sickle cell disease patients, those anticipating multiple transfusions, or pregnant patients, order "extended RBC phenotype" or "extended antigen typing" that includes C, c, E, e (Rh antigens) and K (Kell antigen) at minimum 1
- Genotyping is preferred over serologic phenotyping when available for these extended panels 1
Special Population Considerations
- For patients with bleeding disorders being evaluated, ABO blood group should be performed as part of first-line testing because blood type O is associated with lower von Willebrand factor levels, which affects bleeding risk assessment 1, 3
- This is performed by 70% of specialists evaluating bleeding disorders 1
Sample Collection Requirements
- Blood samples must be collected and labeled at the patient's bedside with at least two unique identifiers to prevent patient/sample confusion 1
- Sample validity is 72 hours if the patient has been transfused or pregnant within the previous 3 months 1
Common Pitfalls to Avoid
- Do not confuse "type and screen" with simple blood typing - "type and screen" is a pre-transfusion test that includes ABO/Rh typing PLUS antibody screening, which is more than what's needed just to know your blood type 4, 5
- Be aware that certain medications (such as daratumumab) and conditions (such as recent transfusions, stem cell transplantation, or rare antibodies) can complicate blood group determination 6
- If there are problems with blood group determination, early consultation with transfusion medicine is essential 6