Coombs test

Question 1

Autoimmune hemolytic anemias are usually Coombs ____

Answer 1

⊕ (positive)

Question 2

Direct Coombs test procedure

Answer 2

• Anti-Ig antibody (Coombs reagent) added to patient’s RBCs
• RBCs agglutinate if RBCs are coated with Ig

Question 3

Indirect Coombs test procedure

Answer 3

• Normal RBCs added to patient’s serum
• If serum has anti-RBC surface Ig, RBCs agglutinate when Coombs reagent added

Memory aid:

• i_N_direct
• _N_ormal RBC

Question 4

What does a positive direct Coombs test represent?

Answer 4

A direct Coombs test adds anti-immunoglobulin G antibodies to the patient;s red blood cells; if agglutination occurs, it indicates that the patient’s red blood cells are covered with immunoglobulin G antibodies

• Memory aid:*
• Direct adds antig (anti-IgG)

Question 5

What does a positive indirect Coombs’ test represent?

Answer 5

An indirect Coombs’ test adds normal red blood cells to the patient’s serum; if agglutination occurs, it indicates that the patient has anti-red blood cell antibodies in serum

• Memory aid:*
• N–direct adds Normal RBCs