Pathology/Lab Coding Alert

Question: What’s the difference between type, screen and crossmatch for blood transfusion testing, and what codes describe these services?

Minnesota Subscriber

Answer: “Blood type” indicates the presence or absence of specific antigens on the surface of red blood cells (RBCs). Although there are hundreds of possible antigens, the most significant for the purpose of blood transfusion are A, B, and Rh (D). CPT^® provides two codes for common serologic testing for these RBC antigens:

• 86900 (Blood typing, serologic; ABO)
• 86901 (… Rh (D))

These are typically the first tests performed prior to a blood transfusion to identify the patient’s blood type. The 86900 test identifies the blood type as A, B, AB, or O (which is the absence of the A or B antigen). The 86901 test identifies the blood type as Rh+ or Rh- (whether the patient has or doesn’t have the Rh (D) antigen.

Screen: After determining the patient’s blood type, the lab typically performs an antibody screen to see if the patient has antibodies to any other RBC antigens, indicating that a blood transfusion containing a complementary antigen might not be compatible. The most common test for a pre-transfusion antibody screen is 86850 (Antibody screen, RBC, each serum technique).

If the antibody screen is negative, meaning that the patient has none of the common antibodies that could cause a transfusion reaction, then a compatible blood type unit can be selected for transfusion.

Final step: Although a transfusion reaction is highly unlikely when a patient with a negative antibody screen receives a compatible blood type, facilities typically employ one final safeguard, which is a compatibility test or crossmatch.

One way to do that for patients with two or more blood-type results on file and a negative antibody screen is a “computer crossmatch” (86923, Compatibility test each unit; electronic). This isn’t a lab test at all, but just a way for the lab information system to affirm that the unit pulled for transfusion matches the patient’s ABO and Rh blood type.

The common lab test for compatibility is 86920 (Compatibility test each unit; immediate spin technique). The test is a quick way to mix patient blood with blood from the transfusion unit to see if any agglutination (clumping) occurs, indicating an incompatibility. .