How many blood samples are required for a group and save (blood typing and antibody screening) test and why?

Group and Save Blood Testing Requirements

A group and save (blood typing and antibody screening) typically requires one blood sample, but a second sample may be required in certain circumstances to ensure patient safety and prevent ABO incompatibility errors. 1

Standard Requirements for Group and Save

Single Sample Protocol

• One properly collected blood sample is typically sufficient for a standard group and save test when:
  • The patient has no history of transfusion in the past 3 months
  • The patient has not been pregnant in the past 3 months
  • There is a valid historical sample available for comparison 1

Two Sample Requirement Scenarios

Blood banks may require two separate samples in the following situations:

• When there is no valid historical sample on file for comparison
• When electronic transmission of results with no manual intervention cannot be guaranteed
• For patients who have received a blood transfusion within the previous 3 months
• For patients who have been pregnant within the previous 3 months (sample validity reduced to 72 hours) 1

Rationale for Sample Requirements

Patient Safety

The primary reason for potentially requiring two samples is to prevent wrong-blood-in-tube errors and the risk of ABO incompatibility, which can lead to fatal transfusion reactions 1. This verification process significantly reduces the risk of mistransfusion, which is considered a preventable adverse event 2.

Regulatory Requirements

• The Association of Anaesthetists guidelines emphasize that positive patient identification is paramount prior to any blood transfusion 1
• AABB (American Association of Blood Banks) and College of American Pathologists (CAP) regulations require blood banks to address the risk of misidentification of a patient's blood type 2

Methods for Second Sample Verification

When two samples are required, the verification can be accomplished by:

1. Testing a second sample collected at a different time from the first sample
2. Comparison with previous valid laboratory records
3. Using an electronic identification verification system or mechanical barrier system (if available) 2

Sample Validity Timeframes

• Standard group and save samples are typically valid for extended periods (often months) if the patient has no history of transfusion or pregnancy
• If a patient has received a blood transfusion or been pregnant within the previous 3 months, the sample is only valid for 72 hours from collection to subsequent transfusion 1

Clinical Benefits of Group and Save Protocol

The type and screen (group and save) protocol offers significant advantages:

• Reduces turnaround time for blood provision compared to full crossmatching (51.24 vs. 71.56 minutes for first transfusions) 3
• Allows for more efficient distribution of limited blood supplies 4
• Enables more effective utilization of blood bank technologist time 4
• Is 99.99% effective in preventing transfusion of incompatible blood when proper screening is performed 4

Common Pitfalls to Avoid

• Inadequate patient identification: Always ensure proper patient identification with minimum identifiers including surname, forename, date of birth, and hospital unique identification number 1
• Improper sample collection: Blood samples must be collected and labeled at the patient's side by appropriately trained personnel 1
• Overlooking recent transfusions or pregnancies: These significantly reduce sample validity periods and may necessitate additional testing 1
• Failure to check for historical samples: Utilizing valid historical samples can eliminate the need for a second sample collection 1

By following these guidelines, healthcare providers can ensure safe and efficient blood typing while minimizing the risk of transfusion-related adverse events.