MLT GlobeBlood Banking: Crossmatch & compatibility – page 3
51 Blood Banking MCQs on Crossmatch & compatibility with answers and explanations.
Under a maximum surgical blood order schedule (MSBOS), procedures that rarely need blood are usually managed by:
For procedures with low transfusion likelihood, type and screen is enough; units can be issued quickly if needed. This reduces unnecessary crossmatches and keeps inventory available.
A patient has anti-M that reacts only at room temperature and not at 37 °C or AHG. What red cells should be given?
Anti-M that does not react at 37 °C is not clinically significant, so antigen-negative units are not needed. Crossmatch-compatible units at 37 °C/AHG are acceptable.
A patient with sickle cell disease will start chronic transfusion. To reduce alloimmunization, which red cells are recommended?
Patients with sickle cell disease have high rates of alloimmunization. Guidelines recommend prophylactic matching for Rh (C, E, or C/c, E/e) and K antigens.
A group AB patient needs plasma. Which plasma group is ABO-compatible?
Group AB red cells carry both A and B antigens, so plasma must contain neither anti-A nor anti-B. Only group AB plasma meets this.
The name on a pretransfusion sample tube does not match the name on the request form. What is the correct action?
Mislabeled or mismatched samples must be rejected because they may come from the wrong patient. Labels must never be corrected in the laboratory.
Uncrossmatched red cells were issued in an emergency. What should the laboratory do afterwards?
Emergency release does not remove the need for testing. Standard tests are completed as soon as possible, and any incompatibility is reported urgently so the patient can be watched or treated.
A patient has anti-c and anti-K. About 20% of donors are c-negative and 91% are K-negative. About how many random units must be tested to find 2 compatible units?
Frequency of c−K− units = 0.20 × 0.91 = 0.182. Units needed = 2 ÷ 0.182 ≈ 11. Using only the c-negative frequency (10 units) underestimates the number.
A group A patient's immediate-spin crossmatches are incompatible with group A units. Her red cells do not react with Dolichos biflorus lectin, and her plasma agglutinates A1 cells. The best red cell choice is:
This A2 (or weak A subgroup) patient has anti-A1 reacting at room temperature. Group O red cells avoid the A1 antigen and are compatible.
A group A patient received 8 units of low-titer group O whole blood. Now type-specific (group A) red cells are requested. Which step is most appropriate first?
Large volumes of group O plasma can leave passive anti-A in the patient. Before switching to group A red cells, the sample should be checked (e.g., reverse group, crossmatch) for anti-A.
A group A patient receives a stem cell transplant from a group O donor. Until conversion is complete, which components are appropriate?
This is a minor ABO mismatch (donor plasma has anti-A). Red cells must be compatible with the donor's anti-A (group O), and plasma must be compatible with the recipient's A cells (A or AB).
A group O patient receives a stem cell transplant from a group A donor. Which red cells should be given early after transplant?
In a major ABO mismatch, the recipient still makes anti-A, so group O red cells are given until anti-A disappears. Plasma should be group A or AB to protect the new donor-derived A cells.