What is a type and screen (blood typing and antibody screening)?

Type and Screen in Blood Transfusion Safety

A type and screen is a laboratory procedure that involves determining a patient's blood type (ABO and Rh) and screening for unexpected antibodies to facilitate safe blood transfusion and expedite the process of finding compatible blood when needed. 1

Components of Type and Screen

Blood Typing

• Determines the patient's ABO blood group and Rh factor (positive or negative)
• Performed using standardized laboratory methods including:
  • Direct typing: Testing red blood cells with known antisera
  • Indirect typing: Testing serum with known red blood cells
• Requires proper patient identification and sample collection
  • Sample must be labeled at the patient's bedside by trained personnel
  • Sample validity is limited to 72 hours if the patient has received a transfusion or been pregnant in the last 3 months 1

Antibody Screening

• Tests the patient's serum for unexpected antibodies against red blood cell antigens
• Detects antibodies that could cause transfusion reactions
• Screening cells used can detect approximately 96% of clinically significant antibodies 2
• When combined with proper typing, provides 99.99% effectiveness in preventing incompatible blood transfusions 2, 3

Purpose and Benefits

The type and screen procedure serves several important purposes:

1. Preparation for potential transfusion: Allows blood bank to identify compatible units quickly if transfusion becomes necessary
2. Prevention of transfusion reactions: Early identification of antibodies helps prevent hemolytic transfusion reactions
3. Expedited blood availability: For patients with positive antibody screens, early identification facilitates finding compatible units
4. Resource optimization: Reduces unnecessary crossmatching when transfusion is unlikely 4, 5
5. Cost reduction: Decreases patient charges and allows more efficient distribution of limited blood supplies 2

Clinical Applications

Standard Practice

• Recommended before any procedure where blood transfusion might be needed
• Essential component of preoperative preparation for many surgical procedures
• Particularly important for patients with sickle cell disease who require extended red cell antigen profiling 6

Special Considerations

• For patients with sickle cell disease, an extended red blood cell antigen profile is recommended, including ABO/RhD, Rh (C/c, E/e), and K antigens 6
• This extended profiling facilitates antibody identification and selection of compatible donor units for patients who are more likely to develop antibodies 6

Efficiency Improvements

• Implementation of type and screen policies has significantly reduced crossmatch-to-transfusion ratios in hospitals 4, 5
• Recent research suggests that selective use of type and screen orders can further reduce unnecessary testing in certain surgical procedures where transfusion is rare 7

Limitations

• The screening cells may not detect antibodies against low-frequency antigens not present on the screening cells
• In emergency situations, an immediate spin crossmatch may be performed in addition to type and screen to verify ABO compatibility and detect high-titer antibodies 3
• Requires availability of moderate blood reserves for immediate transfusion if needed 3

Type and screen has become the standard practice in modern transfusion medicine, balancing safety with resource utilization and cost-effectiveness. It provides nearly complete protection against incompatible transfusions while streamlining the blood banking process.