Transfusion for a patient of cis-AB blood type undergoing a redo cardiac operation

S. Z. Yoon, H. M. Lee, H. S. Kim, S. D. Kim, A. Y. Oh and C. S. Kim*

Department of Anaesthesiology and Pain Medicine, College of Medicine, Seoul National University, Seoul, Korea

* Corresponding author. E-mail: Monday1031{at}yahoo.co.kr

Accepted for publication January 7, 2005.


    Abstract
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 Abstract
 Introduction
 Case report
 Discussion
 References
 
cis-AB, a rare ABO genotype, is the result of a mutated gene resulting in dual specific hybrid enzymes. A single-point mutation reverses the specificity of human blood group B synthesizing galactosyltransferase. This may lead to misclassification in ABO grouping and adverse transfusion reactions. Recently, the authors experienced a case of a patient with cis-AB blood type undergoing pulmonary valve replacement and tricuspid valvuloplasty. We transfused the patient with Rh+ A packed red blood cell, fresh frozen plasma and platelet concentrates without any clinically significant transfusion reactions.

Keywords: blood, transfusion


    Introduction
 Top
 Abstract
 Introduction
 Case report
 Discussion
 References
 
cis-AB type blood, a subtype of type AB blood, may be misclassified since it has a different inheritance from Mendelian laws. Once it is properly classified, it is still necessary to choose the best suitable blood type to transfuse. Most reports on cis-AB type have been concerned with aspects of heredity or subtypes of blood groups. There are few reports of transfusions for patients with the cis-AB blood type.

We report a case in which we transfused Rh+ A packed red blood cells (RBC), type Rh+ A fresh frozen plasma, and type Rh+ A platelet concentrates to a patient with type cis-AB blood during a redo cardiac operation without any adverse reactions, although the same patient had been transfused with Rh+ AB blood during the initial cardiac operation in infancy.


    Case report
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 Abstract
 Introduction
 Case report
 Discussion
 References
 
A 14-year-old boy (height 164 cm, weight 62 kg) was scheduled to undergo pulmonary valve replacement and tricuspid valvuloplasty. As a child, he had been diagnosed with tetralogy of Fallot with an atrial septal defect and pulmonary valve stenosis. At the age of 13 months this malformation was corrected with a patch closure of the atrial septal and ventricular septal defects, a ligation of the patent ductus arteriosus and a pulmonary artery angioplasty. At that time, the patient's blood type was tested as Rh+ AB. He was transfused with one unit of Rh+ AB fresh frozen plasma and three units of Rh+ AB platelet concentrates perioperatively, and 400 ml of whole blood was used to prime the cardiopulmonary bypass (CPB) circuit. After the operation, he was transfused with Rh+ AB whole blood 120 ml, fresh frozen plasma 275 ml and platelet concentrates 9 ml. No clinically significant transfusion reactions were observed.

One month before the current hospital admission the patient suffered sudden chest pain. Echocardiography and cardiac catheterization revealed serious right ventricular enlargement, mild to moderate tricuspid valve regurgitation, moderate pulmonary valve regurgitation and an enlarged right ventricular outflow tract. Serological testing revealed A2B weak and a weak non-autoreactive anti-B antibody, suggestive of the presence of a cis-AB blood group (Table 1).


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Table 1 The patient's ABO and Rh type; mf, mixed field

 
During dissection of adhesions caused by the first operation, a right ventricle rupture occurred, with 800–1000 ml of acute blood loss. Hydroxyethyl starch solution (Voluven®, Fresenius Kabi, Germany) was given and when haematocrit had fallen to 27% one unit of type Rh+ A RBC was administered. A second unit of type Rh+ A RBC was used to prime the CPB circuit. On completing the valve replacement, the patient was weaned from the CPB without problem. A third unit of type Rh+ A RBC was given at a haematocrit of 22%.

Owing to continuous bleeding in the paediatric intensive care unit, the patient was transfused with another five units of type Rh+ A RBCs, four units of type Rh+ A fresh frozen plasma and type Rh+ A platelets on postoperative day 1. On postoperative day 2, his haematocrit was 30%. A total of 10 units of type Rh+ A RBCs, seven units of type Rh+ A fresh frozen plasma and one unit of type Rh+ A platelets were transfused. Clinically, no adverse transfusion reactions were observed.

To assess potential haemolysis due to transfusion, direct and indirect antiglobulin tests were performed six times: before transfusion, immediately after transfusion of type Rh+ A RBCs, before transfusion of type Rh+ A fresh frozen plasma and after completing transfusion on postoperative days 1 and 2. All results from these tests were negative, suggesting the absence of transfusion-related haemolysis. The patient was transferred to the ward on postoperative day 1 and was discharged on postoperative day 8.

To confirm the patient's blood type, ABO genotyping was performed using the polymerase chain reaction–restriction fragment length polymorphism (PCR–RFLP) method. The patient's allele was allele O: del-C-C-G-C-G and allele cis-AB: G-T-C-G-C-C, confirming the patient's ABO genotype as type O/cis-AB. Blood testing of the patient's parents and brothers could not be done for logistic reasons.


    Discussion
 Top
 Abstract
 Introduction
 Case report
 Discussion
 References
 
Type cis-AB blood does not obey Mendel's laws of inheritance, which may cause problems in ABO blood typing and result in transfusion reactions. The existence of anti-B should be considered before transfusing a patient with type cis-AB blood. Haemolysis may occur if a patient with type cis-AB blood is transfused with type AB RBC, whereas type AB serum transfusion should not be problematic. Theoretically, type O or A packed RBCs can be used for a patient with type cis-AB blood group. The existence of anti-B in type O or A blood plasma or platelets may cause a problem when transfusing into a patient with type cis-AB blood. However, because B-antigen expression is often low in patients with type cis-AB blood, it is unlikely to cause a clinical problem. If anti-B exists in the patient's serum at a relatively high titre, type A or O packed RBC should be used and type AB plasma should be considered.

An alternative approach in such patients is to store the patient's own blood before the operation.1 The recommendation in our case would be that the patient be transfused with type A (or O) packed RBC, type AB fresh frozen plasma and type AB platelet concentrates. However, his parents wanted him to receive a directed transfusion from close friends whose type A RBCs and fresh frozen plasma were prepared for transfusion.

The total amount of blood transfused to this patient perioperatively was 70% of his blood volume. Despite such a large amount of blood, no clinical symptoms or signs of adverse transfusion reaction were observed. Interestingly, no haemolytic reaction between the anti-B antibody of the donated blood and the native B-antigen of the patient's RBC occurred. The amount of anti-B antibodies in the blood products administered might have been too low to result in a severe transfusion reaction. However, and probably more importantly, the patient in our case report had a weak B-antigen, indicated by the fact that his blood showed a mixed field agglutination reaction when mixed with anti-B antibodies. This might be the reason for the absence of a reaction between the transfused anti-B antibodies and the patient's weak B-antigen.

Interestingly, no clinically adverse reaction was observed when the patient was transfused with 520 ml of whole AB blood during his first operation at the age of 13 months. It is probable that AB blood was used in the first operation because diagnosis was based on an inadequate diagnostic technique or lack of knowledge of type cis-AB blood at that time. AB-antigen maturation may have been incomplete. It has been reported that AB-antigens are present in the embryo at 5–6 weeks and then continuously increase in number, go through more complex branching, and ultimately mature to the adult level 2–4 yr after birth. Moreover, ABO blood type antibodies begin to appear at the age of 3–6 months and reach adult level only at the age of 5–10 years. According to the transfusion test guidelines, blood cell typing results should prevail for infants who are ≥1 yr old because they may not have anti-A and anti-B in their serum.2 Therefore we can assume that the anti-titre of a 13-month-old infant, in the presence of cis-AB blood group antigens, is low enough for no clinically adverse reaction to occur even if type AB blood is transfused.

In conclusion, we report an exceptional case in which we successfully transfused type A blood corresponding to approximately 70% of the circulatory volume into a patient with type cis-AB blood without any adverse reaction.


    References
 Top
 Abstract
 Introduction
 Case report
 Discussion
 References
 
1 Kawahito S, Kitahata H, Kimura H, Tanaka K, Oshita S. Autotransfusion performed on a patient with cis-AB blood group. Br J Anaesth 1999; 83: 491–2[Abstract/Free Full Text]

2 Han KS. Blood type In: Han KS, Park MH, Kim SI, eds. Transfusion Medicine, 2nd edn. Seoul: Korea Medical, 1999; 198–324





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