Clinical History:
- A 40-year-old woman presents with right upper quadrant pain and your surgical team decides to perform a cholecystectomy. Your resident asked you to write pre-operative orders and to include a "type and screen". While performing the assigned task, your intern looks at the orders, makes a condescending remark, and tells you to order a "type and crossmatch" for four units.
- What is a "type"?
A "type" includes a "front type" and a "back type". The "front type" determines which antigens in the ABO blood group system are on the patient's red blood cells as follows:
- A antigen only = type A
- B antigen only = type B
- A and B antigen = type AB
- Neither A or B = type O
The "back type" identifies the isohemagglutinin in the patient's serum and should correspond to the antigens found on the red blood cells as follows:
- anti-B with type A
- anti-A with type B
- anti-A and anti-B with type O
- neither anti-A or anti-B with type AB
In addition, RBC's are Rh typed and identified as "D" positive or negative.
- What is a "screen"?
A "screen" looks for unexpected red cell alloantibodies which may form following pregnancy or prior transfusions. If the screen is positive, the antibody is identified and 2 units lacking the corresponding antigen are crossmatched for the patient. The physician is also notified. Antibody identification can be complicated and take more than a day to complete.
- What is the cost of a "type and screen"?
A type and screen is in the range of $75 - $100 US.
- What is a "type and cross"?
A "type and cross" determines compatibility between patient serum and donor red blood cells.
- What does a "type and cross" cost?
A type and cross is $75 - $100 US for the screen, which must be performed anyway, and an additional $75 - 100 per unit crossmatched.
- How does a type and crossmatch impact the Blood Bank inventory?
Every unit crossmatched is removed from the general inventory and reserved for the patient for 72 hours. Units which are crossmatched unnecessarily will deplete Blood Bank inventories and can result in blood shortages, such as those which occurred in California after the earthquake. Blood shortages can result in cancellation of elective surgical procedures.
Further history:
- You decide to order a type and screen. During the cholecystectomy the patient starts hemorrhaging. The Blood Bank is told to crossmatch 8 units of blood. The Blood Bank says that the crossmatch will take 45 minutes, but type specific blood is available immediately, if a physician will sign an Emergency Release Form. The patient's blood pressure is dropping quickly, but your intern tells the Blood Bank to have the crossmatched blood ready in 10 minutes, or else. The intern refuses to take blood unless it is crossmatched.
- What should be done?
A full crossmatch takes 45 minutes to complete, and this cannot be shortened, no matter how belligerant a physician becomes. In fact, arguing is counterproductive because it takes time away from performing important work. If the patient is hemorrhaging, sign the emergency release for type specific blood.
- What is the risk of a hemolytic transfusion reaction with type specific blood, if the screen is negative?
The risk of hemolysis using type specific blood, when the antibody screen is negative, is approximately 1/250,000.
- Were you wrong for not getting blood crossmatched preoperatively?
A type and screen should be ordered when there is a less than 10% chance of using blood.
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