Blood grouping

Blood grouping

PART 1. Blood grouping

Introduction

ABO blood grouping is the most important serological test performed in blood compatibility testing – this is because the antibodies of the system (anti-A and anti-B) are preformed and can cause a rapid transfusion reaction if the wrong group is given. The Rhesus system is also important, but as the antibodies are not present unless there has been a previous exposure to the Rhesus antigen in a Rhesus negative individual, this is less critical than ABO grouping.

‘Forward’ ABO blood grouping is now done with monoclonal, separate anti-A and anti-B reagents used against the patient’s red cells (historically, polyclonal anti-A, anti-B, and anti-A, B together reagents were used). A and B red cells are also used for ‘reverse grouping,’ i.e., the patient’s serum is tested against known A and B group red blood cells to check that it agglutinates them appropriately. Any discrepancies between the forward and reverse group need to be investigated using the patient’s original blood sample rather than any cell suspensions created from it to prevent accumulating errors.

1. ABO and Rhesus grouping

Discussion points:

• Draw your results onto the diagram below.

2) What are the blood groups of your four samples? What blood groups could these patients receive during a red blood cell transfusion (i.e., which group(s) is/are compatible with each of them?)

• What are the common causes of false-positive and false-negative reactions in ABO blood grouping? (Maximum 150 words)

The most common causes of false negative and false positive reactions in ABO blood grouping is technical or human error. False-negative reactions in ABO blood grouping are caused by inadequate antigen-antibody ratio, missing or weak antibodies in patients with immunodeficiency and hypogammaglobulinemia, and weak subgroups of A or B which results in mixed or weak field agglutination reactions. Lastly, chemical or bacterial contamination of test material can cause false-negative reactions. On the other hand, false-positive reactions may occur from rouleaux formation due to the elevated fibrinogen, elevated globulin, or dextran expanders. Also, rouleaux results from plasma abnormalities. Autoagglutination as a result of potent col autoantibodies and polyagglutination both microbial associated and nonmicrobial-associated results to false-positive reactions. Lastly, antibody-coated red blood cells resulting from transfusion reaction and warm autoantibodies also contributes to ABO blood group discrepancy (Tyagi and Tyagi, 2013).

4) In the diagram below, which represents forward grouping, red cell suspensions are added to each of the wells first, then anti-sera is added. Draw the expected results in the diagram.

5) In the diagram below, which shows reverse grouping, the patient’s sera are added to each of the wells first, then reagent red cells are added. Draw the expected results in the diagram.

PART 2.   Column agglutination technology 

These are based on the principles of size exclusion chromatography. They use the same system for ABO and Rhesus grouping that you have used (i.e., anti-A, anti-B and anti-D [the latter in duplicate] for forward grouping, and known group A and B red cells for reverse grouping), but reagents are in small tubes containing a gel, within a larger cassette. The patient’s red cells are added to the small tubes containing anti-A, anti-B or anti-D, and their plasma to tubes containing group A and group B cells, and once an agglutination reaction has had time to occur, the cassette is spun in a centrifuge. Where agglutination has occurred, the large clumps of cells are unable to pass through the small spaces in the gel, and the clump remains at the top of the column. Where agglutination has not occurred, the small, free cells are able to pass through the column and can be seen at the base of the tube in the cassette. The principle of size exclusion chromatography will be demonstrated, and you will use two samples of patient red blood cells and serum on Diamed blood grouping cassettes to establish (and cross-check) the ABO and Rhesus groups of these patients.

Discussion points

6) Draw your results onto the blank cassettes shown below and identify the blood groups of the two samples, respectively.

   Known sample:                                     Unknown sample:

   What is the Blood group:                                              Blood group:                                    

7) Red cell transfusion in warm-antibody autoimmune hemolytic anemia presents difficulty in crossmatching, and it is nearly always impossible to find truly serocompatible donor blood. Discuss the strategies of red cell transfusion in patients with severe autoimmune hemolytic anemia. (maximum 300 words)

There are various strategies that can be employed for red cell transfusion in patients with severe autoimmune hemolytic anemia. This procedure starts with the evaluation of the patient, both clinical and laboratory evaluation, to conduct specialized compatibility tests to establish the absence or presence of RBC alloantibodies, which are likely to result in a hemolytic transfusion reaction. The first-line treatment of a person with AIHA comprises glucocorticoids that normally give rise to early improvement of a hemolytic state that interrupts the level of hemoglobin decrease. Also, the anti-CD20 monoclonal antibody is used to rapidly decrease hemolysis and thus rendering it necessary to transfuse RBC.

8) Describe the consequences of receiving ABO-mismatched red blood transfusions. Explain the mechanisms by which the consequences may arise and summarise the clinical features associated with the consequences.  (maximum 400 words) *important*

An incompatible transfusion of ABO blood group will result in an acute immune hemolytic transfusion reaction (Josephson, Castillejo, Grima, and Hillyer, 2010). The RBCs’ surfaces are covered with inherited antigens, and the immune transfusion reactions take place whenever the plasma of the recipient has a significant antibody to antigens existing on the surfaces of the red cells from the donor. The antigen/antibody binding gives rise to hemolysis, most often acute reactions. Also, it gives rise to a life-threatening condition, namely anaphylactoid reaction. This particular condition is likely to result in death if there is no immediate cessation of the transfusion. It also needs an immediate infusion of antihistamines, epinephrine, and other necessities to combat the issue.  Intravascular hemolysis and, on some occasions, combined with the multiorgan failure are often exhibited mismatched transfusions. This condition results from the severe antibody reactions that take place between circulating alloantibodies and their corresponding antigens of the mismatched RBC. Antigen/antibody binding results in red-cell agglutination, followed by activation of the complement proteins. These proteins include C3a, C4a, and C5a, which are responsible for various systemic effects of ABO-incompatible transfusion reactions, including rigors, fever, flushing of the face, reduction in blood pressure, and pain in legs and loins (Blumberg, Heal, Hicks, and Risher, 2001).

Hypovolemic shock is the most significant clinical effect of ABO-mismatch transfusions resulting in disseminated intravascular coagulation and acute renal failure. The patient exhibits depletion of the plasma coagulation factors and an increased risk of severe life-threatening hemorrhages. The most frequent clinical outcomes of the mismatch include fever or chills, hypotension, hemoglobinemia, and hemoglobinuria. Other outcomes include shock, acute renal failure, dyspnea, and disseminated intravascular coagulation.  The incompatible does not necessarily result in death and even does not automatically result in the occurrence of symptoms. If promptly recognized by the doctor and the transfusion discontinued would significantly improve the condition of the patient because transfusing less ABO-mismatched blood may reduce the signs and symptoms and hence preventing death.

Concerning the sources of mis-transfusion, Worel (2016) cites improper identification of the patient at the time of initial blood sampling, switching compatible labels, and testing the wrong sample. Other sources include errors in typing and misidentification of the blood product or the patient at the time of the transfusion.

9) Discuss the laboratory investigations for patients with suspected acute hemolytic transfusion reactions. (maximum 350 words)

According to Delaney et al., (2016), the primary workup for the samples that have been suspected of causing acute hemolytic transfusion reactions is first standardized. Every unit that is taken back to the blood bank needs to be examined for the second visual check for labeling, any evidence for bacterial contamination or hemolysis, and integrity. Also, whenever there is a suspected hemolytic reaction, the blood back must be recalled, and any suspected components quarantined. Often reports of severe or moderate transfusion reactions are given, and these require testing to rule out the acute hemolytic transfer reaction. These tests include repeat rhesus (D) and ABO grouping of the returned unit and the patient sample. A repeat antibody screening of both the post- and pre-transfusion samples is done, followed by the repeat cross-matching of the samples and the returned unit, as well as the DAT is performed on the post-transfusion blood sample. If the DAT of the patient turns out to be positive after the transfusion, the RBC compatibility is suspected as the primary cause of HTR, given that the RBCs’ donor revels a negative DAT (Sadani, Urbaniak, Bruce, and Tighe, 2006). This step is followed by checking the identity at least by assessing the D and ABO of the post and pretransfusion blood samples and the donor’s blood from the blood bag. This sample is utilized for cross-match.

Further evaluation of the hemolytic transfer reaction that results from red blood cell concentrate comprises the antibody screening tests obtain from the recipient before and after transfusion and the patient’s plasma as well as the RBC taken from the blood bag (Webster, 1980). Both antibody screening test and ABO typing of the donor’s plasma is carried about if the PC or FFP has caused the HTR. Also, cross-matching is done with the patient’s RBCs and the plasma from the blood bag. Whenever the polyspecific DAT turns positive, further investigation is performed through monospecific DATs to test for immunoglobulin and C3c and C3d complement factors. Also, an antibody elution from the RBCs is performed to establish the antibody. The positive outcome of the cross-match and antibody screening test within the plasma prompts antibody identification (Sahu and Hemlata, 2014).

PART 3. Antibody screening

Antibody screening is usually undertaken at the same time as blood grouping, and is important in antenatal patients (who may have or develop antibodies that will affect the fetus/baby), and prior to transfusion. It works by taking some of the patient’s serum and mixing it with at least two different preparations of group O red blood cells (i.e., eliminating the potential effects of anti-A and anti-B antibodies that the patient has anyway – these cannot react against group O cells). These group O cells will have been tested and are known to express a minimum set of antigens. In the UK, the minimum set of antigens is:

C, c, D, E, K, k, Fya, Fyb, Jka, Jkb, S, s, M, N, and Lea

Ideally, red cells should be homozygous for antigens (e.g., one set of Group O cells should be SS and the other ss) to get the maximum agglutination reaction from any antibodies present in the patient’s serum, so multiple sets of Group O cells are needed.

Small volumes of the patient’s serum are added to each tube within a cassette – each tube contains Group O red blood cells which express known antigens, and an anti-human immunoglobulin. If the patient’s serum contains antibodies against any of the antigens on the red blood cells, binding of the antibody to the antigen occurs. The anti-human globulin present in the tube then causes the antibody-coated red blood cells to cross-link and agglutinate into clumps.

Discussion points

10) A 30-year-old female at 39 weeks of gestation was admitted to the Obstetric unit for a Caesarean section (C-section). She had a history of C-section 4 years before this visit. A sample (ethylenediaminetetraacetic acid [EDTA] anticoagulant) was submitted to the blood bank for type and screen along with an order for two units of red blood cells. The patient had no history of prior transfusion.

The blood group typing results were shown as below.

Antibody screening and identification showed the presence of anti-Le^a antibodies.

What is the patient’s ABO/Rh blood group type? Discuss if the anti-Le^a antibodies are clinically significant. Is there a risk of hemolytic disease of the fetus/newborn (HDFN)? Why or why not?   (maximum 300 words)

The patient’s ABO/Rh blood group type is A+. There is a reaction with anti-A in the forwards typing, and the rhesus factor is positive while in reverse typing, the patient plasma conglutinates with the B cells. The woman possesses the anti-Le^a antibodies, which are clinically significant, especially when they are detected at a temperature of 37^oC, but they are not considered clinically significant when they are not active at this temperature (Whyte and Graham, 1981). This particular antibody is, therefore, not clinically significant. There is the blood of the woman contains anti-D, and therefore there is a potentially clinically significant for causing HDFN. All Rh antibodies have the potential for causing HDFN (Prasad, Krugh, Rossi, and O’Shaughnessy, 2006).

References

Tyagi, S., and Tyagi, A., 2013. Possible correlation of transfusion-transmitted diseases with Rh type and ABO blood group system. Journal of clinical and diagnostic research: JCDR, 7(9), p.1930.

Prasad, M.R., Krugh, D., Rossi, K.Q. and O’Shaughnessy, R.W., 2006. Anti-D in Rh-positive pregnancies. American journal of obstetrics and gynecology, 195(4), pp.1158-1162.

Whyte, J., and Graham, H., 1981. Prediction of the severity of ABO hemolytic disease of the newborn by cord blood tests. Acta Pædiatrica, 70(2), pp.217-222.

Josephson, C.D., Castillejo, M.I., Grima, K., and Hillyer, C.D., 2010. ABO-mismatched platelet transfusions: strategies to mitigate patient exposure to naturally occurring hemolytic antibodies. Transfusion and Apheresis Science, 42(1), pp.83-88.

Blumberg, N., Heal, J.M., Hicks Jr, G.L. and Risher, W.H., 2001. Association of ABO‐mismatched platelet transfusions with morbidity and mortality in cardiac surgery. Transfusion, 41(6), pp.790-793.

Worel, N., 2016. ABO-mismatched allogeneic hematopoietic stem cell transplantation. Transfusion Medicine and Hemotherapy, 43(1), pp.3-12.

Delaney, M., Wendel, S., Bercovitz, R.S., Cid, J., Cohn, C., Dunbar, N.M., Apelseth, T.O., Popovsky, M., Stanworth, S.J., Tinmouth, A., and Van De-Watering, L., 2016. Transfusion reactions: prevention, diagnosis, and treatment. The Lancet, 388(10061), pp.2825-2836.

Sahu, S., and Hemlata, A.V., 2014. Adverse events related to blood transfusion. Indian journal of anesthesia, 58(5), p.543.

Sadani, D.T., Urbaniak, S.J., Bruce, M., and Tighe, J.E., 2006. Repeat ABO‐incompatible platelet transfusions leading to a hemolytic transfusion reaction: transfusion medicine, 16(5), pp.375-379.

Webster, B.H., 1980. Clinical presentation of hemolytic transfusion reactions. Anesthesia and intensive care, 8(2), pp.115-119.

PART 1. Blood grouping

Introduction

ABO blood grouping is the most important serological test performed in blood compatibility testing – this is because the antibodies of the system (anti-A and anti-B) are preformed and can cause a rapid transfusion reaction if the wrong group is given. The Rhesus system is also important, but as the antibodies are not present unless there has been a previous exposure to the Rhesus antigen in a Rhesus negative individual, this is less critical than ABO grouping.

‘Forward’ ABO blood grouping is now done with monoclonal, separate anti-A and anti-B reagents used against the patient’s red cells (historically, polyclonal anti-A, anti-B, and anti-A, B together reagents were used). A and B red cells are also used for ‘reverse grouping,’ i.e., the patient’s serum is tested against known A and B group red blood cells to check that it agglutinates them appropriately. Any discrepancies between the forward and reverse group need to be investigated using the patient’s original blood sample rather than any cell suspensions created from it to prevent accumulating errors.

1. ABO and Rhesus grouping

Discussion points:

• Draw your results onto the diagram below.

2) What are the blood groups of your four samples? What blood groups could these patients receive during a red blood cell transfusion (i.e., which group(s) is/are compatible with each of them?)

• What are the common causes of false-positive and false-negative reactions in ABO blood grouping? (Maximum 150 words)

The most common causes of false negative and false positive reactions in ABO blood grouping is technical or human error. False-negative reactions in ABO blood grouping are caused by inadequate antigen-antibody ratio, missing or weak antibodies in patients with immunodeficiency and hypogammaglobulinemia, and weak subgroups of A or B which results in mixed or weak field agglutination reactions. Lastly, chemical or bacterial contamination of test material can cause false-negative reactions. On the other hand, false-positive reactions may occur from rouleaux formation due to the elevated fibrinogen, elevated globulin, or dextran expanders. Also, rouleaux results from plasma abnormalities. Autoagglutination as a result of potent col autoantibodies and polyagglutination both microbial associated and nonmicrobial-associated results to false-positive reactions. Lastly, antibody-coated red blood cells resulting from transfusion reaction and warm autoantibodies also contributes to ABO blood group discrepancy (Tyagi and Tyagi, 2013).

4) In the diagram below, which represents forward grouping, red cell suspensions are added to each of the wells first, then anti-sera is added. Draw the expected results in the diagram.

5) In the diagram below, which shows reverse grouping, the patient’s sera are added to each of the wells first, then reagent red cells are added. Draw the expected results in the diagram.

PART 2.   Column agglutination technology 

These are based on the principles of size exclusion chromatography. They use the same system for ABO and Rhesus grouping that you have used (i.e., anti-A, anti-B and anti-D [the latter in duplicate] for forward grouping, and known group A and B red cells for reverse grouping), but reagents are in small tubes containing a gel, within a larger cassette. The patient’s red cells are added to the small tubes containing anti-A, anti-B or anti-D, and their plasma to tubes containing group A and group B cells, and once an agglutination reaction has had time to occur, the cassette is spun in a centrifuge. Where agglutination has occurred, the large clumps of cells are unable to pass through the small spaces in the gel, and the clump remains at the top of the column. Where agglutination has not occurred, the small, free cells are able to pass through the column and can be seen at the base of the tube in the cassette. The principle of size exclusion chromatography will be demonstrated, and you will use two samples of patient red blood cells and serum on Diamed blood grouping cassettes to establish (and cross-check) the ABO and Rhesus groups of these patients.

Discussion points

6) Draw your results onto the blank cassettes shown below and identify the blood groups of the two samples, respectively.

   Known sample:                                     Unknown sample:

   What is the Blood group:                                              Blood group:                                    

7) Red cell transfusion in warm-antibody autoimmune hemolytic anemia presents difficulty in crossmatching, and it is nearly always impossible to find truly serocompatible donor blood. Discuss the strategies of red cell transfusion in patients with severe autoimmune hemolytic anemia. (maximum 300 words)

There are various strategies that can be employed for red cell transfusion in patients with severe autoimmune hemolytic anemia. This procedure starts with the evaluation of the patient, both clinical and laboratory evaluation, to conduct specialized compatibility tests to establish the absence or presence of RBC alloantibodies, which are likely to result in a hemolytic transfusion reaction. The first-line treatment of a person with AIHA comprises glucocorticoids that normally give rise to early improvement of a hemolytic state that interrupts the level of hemoglobin decrease. Also, the anti-CD20 monoclonal antibody is used to rapidly decrease hemolysis and thus rendering it necessary to transfuse RBC.

8) Describe the consequences of receiving ABO-mismatched red blood transfusions. Explain the mechanisms by which the consequences may arise and summarise the clinical features associated with the consequences.  (maximum 400 words) *important*

An incompatible transfusion of ABO blood group will result in an acute immune hemolytic transfusion reaction (Josephson, Castillejo, Grima, and Hillyer, 2010). The RBCs’ surfaces are covered with inherited antigens, and the immune transfusion reactions take place whenever the plasma of the recipient has a significant antibody to antigens existing on the surfaces of the red cells from the donor. The antigen/antibody binding gives rise to hemolysis, most often acute reactions. Also, it gives rise to a life-threatening condition, namely anaphylactoid reaction. This particular condition is likely to result in death if there is no immediate cessation of the transfusion. It also needs an immediate infusion of antihistamines, epinephrine, and other necessities to combat the issue.  Intravascular hemolysis and, on some occasions, combined with the multiorgan failure are often exhibited mismatched transfusions. This condition results from the severe antibody reactions that take place between circulating alloantibodies and their corresponding antigens of the mismatched RBC. Antigen/antibody binding results in red-cell agglutination, followed by activation of the complement proteins. These proteins include C3a, C4a, and C5a, which are responsible for various systemic effects of ABO-incompatible transfusion reactions, including rigors, fever, flushing of the face, reduction in blood pressure, and pain in legs and loins (Blumberg, Heal, Hicks, and Risher, 2001).

Hypovolemic shock is the most significant clinical effect of ABO-mismatch transfusions resulting in disseminated intravascular coagulation and acute renal failure. The patient exhibits depletion of the plasma coagulation factors and an increased risk of severe life-threatening hemorrhages. The most frequent clinical outcomes of the mismatch include fever or chills, hypotension, hemoglobinemia, and hemoglobinuria. Other outcomes include shock, acute renal failure, dyspnea, and disseminated intravascular coagulation.  The incompatible does not necessarily result in death and even does not automatically result in the occurrence of symptoms. If promptly recognized by the doctor and the transfusion discontinued would significantly improve the condition of the patient because transfusing less ABO-mismatched blood may reduce the signs and symptoms and hence preventing death.

Concerning the sources of mis-transfusion, Worel (2016) cites improper identification of the patient at the time of initial blood sampling, switching compatible labels, and testing the wrong sample. Other sources include errors in typing and misidentification of the blood product or the patient at the time of the transfusion.

9) Discuss the laboratory investigations for patients with suspected acute hemolytic transfusion reactions. (maximum 350 words)

According to Delaney et al., (2016), the primary workup for the samples that have been suspected of causing acute hemolytic transfusion reactions is first standardized. Every unit that is taken back to the blood bank needs to be examined for the second visual check for labeling, any evidence for bacterial contamination or hemolysis, and integrity. Also, whenever there is a suspected hemolytic reaction, the blood back must be recalled, and any suspected components quarantined. Often reports of severe or moderate transfusion reactions are given, and these require testing to rule out the acute hemolytic transfer reaction. These tests include repeat rhesus (D) and ABO grouping of the returned unit and the patient sample. A repeat antibody screening of both the post- and pre-transfusion samples is done, followed by the repeat cross-matching of the samples and the returned unit, as well as the DAT is performed on the post-transfusion blood sample. If the DAT of the patient turns out to be positive after the transfusion, the RBC compatibility is suspected as the primary cause of HTR, given that the RBCs’ donor revels a negative DAT (Sadani, Urbaniak, Bruce, and Tighe, 2006). This step is followed by checking the identity at least by assessing the D and ABO of the post and pretransfusion blood samples and the donor’s blood from the blood bag. This sample is utilized for cross-match.

Further evaluation of the hemolytic transfer reaction that results from red blood cell concentrate comprises the antibody screening tests obtain from the recipient before and after transfusion and the patient’s plasma as well as the RBC taken from the blood bag (Webster, 1980). Both antibody screening test and ABO typing of the donor’s plasma is carried about if the PC or FFP has caused the HTR. Also, cross-matching is done with the patient’s RBCs and the plasma from the blood bag. Whenever the polyspecific DAT turns positive, further investigation is performed through monospecific DATs to test for immunoglobulin and C3c and C3d complement factors. Also, an antibody elution from the RBCs is performed to establish the antibody. The positive outcome of the cross-match and antibody screening test within the plasma prompts antibody identification (Sahu and Hemlata, 2014).

PART 3. Antibody screening

Antibody screening is usually undertaken at the same time as blood grouping, and is important in antenatal patients (who may have or develop antibodies that will affect the fetus/baby), and prior to transfusion. It works by taking some of the patient’s serum and mixing it with at least two different preparations of group O red blood cells (i.e., eliminating the potential effects of anti-A and anti-B antibodies that the patient has anyway – these cannot react against group O cells). These group O cells will have been tested and are known to express a minimum set of antigens. In the UK, the minimum set of antigens is:

C, c, D, E, K, k, Fya, Fyb, Jka, Jkb, S, s, M, N, and Lea

Ideally, red cells should be homozygous for antigens (e.g., one set of Group O cells should be SS and the other ss) to get the maximum agglutination reaction from any antibodies present in the patient’s serum, so multiple sets of Group O cells are needed.

Small volumes of the patient’s serum are added to each tube within a cassette – each tube contains Group O red blood cells which express known antigens, and an anti-human immunoglobulin. If the patient’s serum contains antibodies against any of the antigens on the red blood cells, binding of the antibody to the antigen occurs. The anti-human globulin present in the tube then causes the antibody-coated red blood cells to cross-link and agglutinate into clumps.

Discussion points

10) A 30-year-old female at 39 weeks of gestation was admitted to the Obstetric unit for a Caesarean section (C-section). She had a history of C-section 4 years before this visit. A sample (ethylenediaminetetraacetic acid [EDTA] anticoagulant) was submitted to the blood bank for type and screen along with an order for two units of red blood cells. The patient had no history of prior transfusion.

The blood group typing results were shown as below.

Antibody screening and identification showed the presence of anti-Le^a antibodies.

What is the patient’s ABO/Rh blood group type? Discuss if the anti-Le^a antibodies are clinically significant. Is there a risk of hemolytic disease of the fetus/newborn (HDFN)? Why or why not?   (maximum 300 words)

The patient’s ABO/Rh blood group type is A+. There is a reaction with anti-A in the forwards typing, and the rhesus factor is positive while in reverse typing, the patient plasma conglutinates with the B cells. The woman possesses the anti-Le^a antibodies, which are clinically significant, especially when they are detected at a temperature of 37^oC, but they are not considered clinically significant when they are not active at this temperature (Whyte and Graham, 1981). This particular antibody is, therefore, not clinically significant. There is the blood of the woman contains anti-D, and therefore there is a potentially clinically significant for causing HDFN. All Rh antibodies have the potential for causing HDFN (Prasad, Krugh, Rossi, and O’Shaughnessy, 2006).

References

Tyagi, S., and Tyagi, A., 2013. Possible correlation of transfusion-transmitted diseases with Rh type and ABO blood group system. Journal of clinical and diagnostic research: JCDR, 7(9), p.1930.

Prasad, M.R., Krugh, D., Rossi, K.Q. and O’Shaughnessy, R.W., 2006. Anti-D in Rh-positive pregnancies. American journal of obstetrics and gynecology, 195(4), pp.1158-1162.

Whyte, J., and Graham, H., 1981. Prediction of the severity of ABO hemolytic disease of the newborn by cord blood tests. Acta Pædiatrica, 70(2), pp.217-222.

Josephson, C.D., Castillejo, M.I., Grima, K., and Hillyer, C.D., 2010. ABO-mismatched platelet transfusions: strategies to mitigate patient exposure to naturally occurring hemolytic antibodies. Transfusion and Apheresis Science, 42(1), pp.83-88.

Blumberg, N., Heal, J.M., Hicks Jr, G.L. and Risher, W.H., 2001. Association of ABO‐mismatched platelet transfusions with morbidity and mortality in cardiac surgery. Transfusion, 41(6), pp.790-793.

Worel, N., 2016. ABO-mismatched allogeneic hematopoietic stem cell transplantation. Transfusion Medicine and Hemotherapy, 43(1), pp.3-12.

Delaney, M., Wendel, S., Bercovitz, R.S., Cid, J., Cohn, C., Dunbar, N.M., Apelseth, T.O., Popovsky, M., Stanworth, S.J., Tinmouth, A., and Van De-Watering, L., 2016. Transfusion reactions: prevention, diagnosis, and treatment. The Lancet, 388(10061), pp.2825-2836.

Sahu, S., and Hemlata, A.V., 2014. Adverse events related to blood transfusion. Indian journal of anesthesia, 58(5), p.543.

Sadani, D.T., Urbaniak, S.J., Bruce, M., and Tighe, J.E., 2006. Repeat ABO‐incompatible platelet transfusions leading to a hemolytic transfusion reaction: transfusion medicine, 16(5), pp.375-379.

Webster, B.H., 1980. Clinical presentation of hemolytic transfusion reactions. Anesthesia and intensive care, 8(2), pp.115-119.