ASCP BOARD OF CERTIFICATION • MEDICAL LABORATORY TECHNICIAN
ASCP MLT EXAM/ PRACTICE AND STUDY GUIDE
Medical Laboratory Technician A+
2026/2027
Official-Style Examination • Blood Bank, Chemistry, Hematology, Microbiology, UA & Lab Ops • Full Rationales
A+ 6 100%
QUESTIONS VERIFIED EXAM DOMAINS COVERED RATIONALES INCLUDED
CATEGORIES
■ Blood Bank (Immunohematology)
■ Clinical Chemistry
■ Hematology
■ Microbiology
■ Urinalysis & Body Fluids
■ Immunology & Laboratory Operations
STUVIAACTUALEXAM
All content original • Aligned to ASCP BOC MLT content guidelines • For educational practice only
, SECTION: BLOOD BANK (IMMUNOHEMATOLOGY)
Q1. A unit of packed red blood cells is ordered for a patient with a history of anti-K. The antibody screen is positive and the antibody identification panel
confirms anti-K. Crossmatch-compatible units must be:
A. Washed units only
B. K-positive to adsorb the antibody
C. K-negative and crossmatch compatible at AHG
D. Any group O unit without antigen typing
Correct Answer: C
Rationale: Units must lack the corresponding antigen (K) and be compatible by AHG crossmatch to prevent hemolytic transfusion reaction.
Q2. A patient types as group A, Rh-positive. The reverse grouping shows no agglutination with A1 or B cells. The most likely explanation is:
A. Cold agglutinin disease only
B. The patient is group AB
C. Hypogammaglobulinemia or age-related weak reverse reactions
D. The forward type is wrong and the patient is group O
Correct Answer: C
Rationale: Weak or missing reverse reactions are common in infants, elderly, or immunocompromised patients with low immunoglobulin levels.
Q3. An antibody screen is performed using LISS. After 37 C incubation and AHG, all screen cells are positive and the autocontrol is negative. The next
step is typically:
A. Issue any unit without further testing
B. Ignore the screen because autocontrol is negative
C. Wash the cells again and report negative
D. Perform antibody identification panel and antigen type the patient for common antigens
Correct Answer: D
Rationale: A positive antibody screen with negative autocontrol indicates alloantibody; identification and antigen-negative units are required.
Q4. A cord blood sample from a newborn of a group O mother shows a positive DAT. The eluate reacts with group A and B cells but not O cells. This
pattern is consistent with:
A. Cold agglutinin disease
B. ABO HDN due to maternal anti-A,B
C. Rh HDN only
D. Warm autoimmune hemolytic anemia
Correct Answer: B
Rationale: Group O mothers can produce IgG anti-A,B that crosses the placenta and causes ABO hemolytic disease of the newborn.
Q5. A patient requires platelets. The inventory has only ABO-incompatible apheresis platelets. The laboratory may issue them when:
A. Rh type must match in all cases
B. The clinical situation is urgent and volume or plasma reduction or out-of-group issuance is accepted per policy
C. Only ABO-identical platelets are ever allowed
D. Platelets must be irradiated first
Correct Answer: B
Rationale: In urgent situations, ABO-incompatible platelets may be issued; plasma volume reduction can minimize hemolysis risk.
Q6. A unit of RBCs is removed from the blood bank refrigerator at 8:00 a.m. and returned at 9:15 a.m. without being spiked. Per standard practice the unit:
A. May be returned to inventory if it has been maintained within acceptable temperature and the container is intact
B. Must be discarded because it left the refrigerator
C. Can be issued only as plasma
D. Must be irradiated before return
Correct Answer: A
Rationale: Unopened units returned within the time/temperature policy may be reissued.
Q7. A patient has a history of anti-E. Current antibody screen is negative. Crossmatch-compatible units should still be:
A. Only group O negative
B. Any Rh-positive unit
C. Not antigen-typed because the screen is negative
D. E-negative because the antibody may be below detectable levels but can respond anamnestically
Correct Answer: D
Rationale: Historically significant antibodies require antigen-negative units even if currently undetectable.
STUVIAACTUALEXAM Page 2 of 17 ASCP MLT
, Q8. The Rh typing of a patient shows 2+ agglutination with anti-D. The weak D test is indicated when:
A. The patient is already known D-positive
B. The initial anti-D is negative or weak and the patient is a candidate for RhIG or a blood donor
C. Only for cord blood samples
D. All patients require weak D testing
Correct Answer: B
Rationale: Weak D testing is performed on apparent D-negative individuals who may receive RhIG or donate blood.
Q9. A crossmatch is performed and the AHG phase shows agglutination. The antibody screen was negative. Possible causes include:
A. The unit is always compatible
B. The patient must be group AB
C. No further investigation is needed
D. Alloantibody to a low-frequency antigen on the donor unit or an error in screening
Correct Answer: D
Rationale: Incompatibility at AHG with a negative screen suggests an antibody to a low-incidence antigen present on the donor cells.
Q10. Cryoprecipitate is primarily indicated for replacement of:
A. Platelets
B. Red cell mass
C. Factor IX only
D. Fibrinogen and factor VIII
Correct Answer: D
Rationale: Cryoprecipitate is rich in fibrinogen, factor VIII, vWF, and factor XIII.
Q11. A patient experiences fever and chills during transfusion but no hemolysis is found. The most common cause of febrile non-hemolytic transfusion
reaction is:
A. ABO incompatibility
B. Bacterial contamination only
C. Recipient antibodies to donor leukocyte antigens or cytokines in the unit
D. Iron overload
Correct Answer: C
Rationale: FNHTR is often caused by anti-HLA/HNA antibodies or accumulated cytokines in stored cellular products.
Q12. Rh immune globulin (RhIG) is indicated for an Rh-negative mother when:
A. The infant is Rh-negative
B. She delivers an Rh-positive infant and has no immune anti-D
C. She is already immunized with anti-D
D. She is group AB
Correct Answer: B
Rationale: RhIG prevents immunization when an Rh-negative mother is exposed to Rh-positive red cells.
Q13. A unit of FFP is thawed at 37 C. After thawing it should be stored at:
A. 37 C continuously
B. 1 to 6 C and transfused within 24 hours or per current standards for thawed plasma
C. Frozen again immediately
D. Room temperature for 5 days
Correct Answer: B
Rationale: Thawed FFP is stored refrigerated and has a limited outdate.
Q14. The major crossmatch consists of:
A. Patient serum plus donor red cells
B. Antibody screen only
C. Patient red cells plus donor plasma
D. Only an immediate-spin ABO check
Correct Answer: A
Rationale: The major crossmatch tests patient serum or plasma against donor red cells for compatibility.
STUVIAACTUALEXAM Page 3 of 17 ASCP MLT
ASCP MLT EXAM/ PRACTICE AND STUDY GUIDE
Medical Laboratory Technician A+
2026/2027
Official-Style Examination • Blood Bank, Chemistry, Hematology, Microbiology, UA & Lab Ops • Full Rationales
A+ 6 100%
QUESTIONS VERIFIED EXAM DOMAINS COVERED RATIONALES INCLUDED
CATEGORIES
■ Blood Bank (Immunohematology)
■ Clinical Chemistry
■ Hematology
■ Microbiology
■ Urinalysis & Body Fluids
■ Immunology & Laboratory Operations
STUVIAACTUALEXAM
All content original • Aligned to ASCP BOC MLT content guidelines • For educational practice only
, SECTION: BLOOD BANK (IMMUNOHEMATOLOGY)
Q1. A unit of packed red blood cells is ordered for a patient with a history of anti-K. The antibody screen is positive and the antibody identification panel
confirms anti-K. Crossmatch-compatible units must be:
A. Washed units only
B. K-positive to adsorb the antibody
C. K-negative and crossmatch compatible at AHG
D. Any group O unit without antigen typing
Correct Answer: C
Rationale: Units must lack the corresponding antigen (K) and be compatible by AHG crossmatch to prevent hemolytic transfusion reaction.
Q2. A patient types as group A, Rh-positive. The reverse grouping shows no agglutination with A1 or B cells. The most likely explanation is:
A. Cold agglutinin disease only
B. The patient is group AB
C. Hypogammaglobulinemia or age-related weak reverse reactions
D. The forward type is wrong and the patient is group O
Correct Answer: C
Rationale: Weak or missing reverse reactions are common in infants, elderly, or immunocompromised patients with low immunoglobulin levels.
Q3. An antibody screen is performed using LISS. After 37 C incubation and AHG, all screen cells are positive and the autocontrol is negative. The next
step is typically:
A. Issue any unit without further testing
B. Ignore the screen because autocontrol is negative
C. Wash the cells again and report negative
D. Perform antibody identification panel and antigen type the patient for common antigens
Correct Answer: D
Rationale: A positive antibody screen with negative autocontrol indicates alloantibody; identification and antigen-negative units are required.
Q4. A cord blood sample from a newborn of a group O mother shows a positive DAT. The eluate reacts with group A and B cells but not O cells. This
pattern is consistent with:
A. Cold agglutinin disease
B. ABO HDN due to maternal anti-A,B
C. Rh HDN only
D. Warm autoimmune hemolytic anemia
Correct Answer: B
Rationale: Group O mothers can produce IgG anti-A,B that crosses the placenta and causes ABO hemolytic disease of the newborn.
Q5. A patient requires platelets. The inventory has only ABO-incompatible apheresis platelets. The laboratory may issue them when:
A. Rh type must match in all cases
B. The clinical situation is urgent and volume or plasma reduction or out-of-group issuance is accepted per policy
C. Only ABO-identical platelets are ever allowed
D. Platelets must be irradiated first
Correct Answer: B
Rationale: In urgent situations, ABO-incompatible platelets may be issued; plasma volume reduction can minimize hemolysis risk.
Q6. A unit of RBCs is removed from the blood bank refrigerator at 8:00 a.m. and returned at 9:15 a.m. without being spiked. Per standard practice the unit:
A. May be returned to inventory if it has been maintained within acceptable temperature and the container is intact
B. Must be discarded because it left the refrigerator
C. Can be issued only as plasma
D. Must be irradiated before return
Correct Answer: A
Rationale: Unopened units returned within the time/temperature policy may be reissued.
Q7. A patient has a history of anti-E. Current antibody screen is negative. Crossmatch-compatible units should still be:
A. Only group O negative
B. Any Rh-positive unit
C. Not antigen-typed because the screen is negative
D. E-negative because the antibody may be below detectable levels but can respond anamnestically
Correct Answer: D
Rationale: Historically significant antibodies require antigen-negative units even if currently undetectable.
STUVIAACTUALEXAM Page 2 of 17 ASCP MLT
, Q8. The Rh typing of a patient shows 2+ agglutination with anti-D. The weak D test is indicated when:
A. The patient is already known D-positive
B. The initial anti-D is negative or weak and the patient is a candidate for RhIG or a blood donor
C. Only for cord blood samples
D. All patients require weak D testing
Correct Answer: B
Rationale: Weak D testing is performed on apparent D-negative individuals who may receive RhIG or donate blood.
Q9. A crossmatch is performed and the AHG phase shows agglutination. The antibody screen was negative. Possible causes include:
A. The unit is always compatible
B. The patient must be group AB
C. No further investigation is needed
D. Alloantibody to a low-frequency antigen on the donor unit or an error in screening
Correct Answer: D
Rationale: Incompatibility at AHG with a negative screen suggests an antibody to a low-incidence antigen present on the donor cells.
Q10. Cryoprecipitate is primarily indicated for replacement of:
A. Platelets
B. Red cell mass
C. Factor IX only
D. Fibrinogen and factor VIII
Correct Answer: D
Rationale: Cryoprecipitate is rich in fibrinogen, factor VIII, vWF, and factor XIII.
Q11. A patient experiences fever and chills during transfusion but no hemolysis is found. The most common cause of febrile non-hemolytic transfusion
reaction is:
A. ABO incompatibility
B. Bacterial contamination only
C. Recipient antibodies to donor leukocyte antigens or cytokines in the unit
D. Iron overload
Correct Answer: C
Rationale: FNHTR is often caused by anti-HLA/HNA antibodies or accumulated cytokines in stored cellular products.
Q12. Rh immune globulin (RhIG) is indicated for an Rh-negative mother when:
A. The infant is Rh-negative
B. She delivers an Rh-positive infant and has no immune anti-D
C. She is already immunized with anti-D
D. She is group AB
Correct Answer: B
Rationale: RhIG prevents immunization when an Rh-negative mother is exposed to Rh-positive red cells.
Q13. A unit of FFP is thawed at 37 C. After thawing it should be stored at:
A. 37 C continuously
B. 1 to 6 C and transfused within 24 hours or per current standards for thawed plasma
C. Frozen again immediately
D. Room temperature for 5 days
Correct Answer: B
Rationale: Thawed FFP is stored refrigerated and has a limited outdate.
Q14. The major crossmatch consists of:
A. Patient serum plus donor red cells
B. Antibody screen only
C. Patient red cells plus donor plasma
D. Only an immediate-spin ABO check
Correct Answer: A
Rationale: The major crossmatch tests patient serum or plasma against donor red cells for compatibility.
STUVIAACTUALEXAM Page 3 of 17 ASCP MLT
