ABO blood group incompatibility between mother and baby

Introduction Maternal and infant ABO blood group incompatibility is a clinical symptom of neonatal maternal and child blood type incompatibility. The blood group incompatible hemolytic disease of the newborn is a hemolytic disease caused by the blood type of the pregnant mother and the baby. It mainly includes ABO and Rh hemolytic disease, which are referred to as neonatal hemolytic disease.

Cause

Maternal and child blood group incompatibility is caused by the blood type antigen lacking in the fetus. There are many types of human blood, but the most important ones are ABO blood type and Rh blood type. In the case of ABO hemolytic disease, the pregnant mother is O-type, and the infant is A-type or B-type. Because A or B substances are widely distributed in nature, pregnant women have been sensitized with substances A and B before the first pregnancy. Therefore, about 50% of ABO hemolytic disease occurs in the first child, while Rh hemolytic disease occurs in the second child. And above. The maternal blood type is Rh negative, the fetus is Rh positive, and the positive blood type of the fetus is from the father of Rh positive heterozygotes.

The Rh blood group system should have six antigens, namely C, c, D, d, E, and e, but no antigen has been found so far. As the antigen on standard red blood cells, there are the following CCDee, ccDEE, ccDee, and Ccdee. Among them, D has the strongest antigenicity and is the most important antigen causing Rh hemolytic disease. Therefore, blood group examination always only checks D antigen, as long as D is positive. The Rh-positive blood type is called, and regardless of whether several other antigens (such as E) are present, the D-free antigen is collectively referred to as the Rh-negative blood type. RhD hemolytic disease blood type must be Rh-negative, while RhE hemolytic disease (in China and Japan after RhD hemolytic disease) pregnant mother must be RhE negative, but if there is D antigen, it is still Rh-positive blood type, and Infants are positive for RhE and become the cause of delay in the diagnosis of RhE hemolytic disease. Therefore, in addition to D in domestic blood tests, E antigen should be added.

In Rh hemolytic disease, the first fetus with D antigen in the process of birth (electrically possible in the uterus) red blood cells have a good chance to enter the mother, the mother will soon produce IgM antibodies, and later produce IgG antibodies, but the amount is small, the speed is slow It takes about 8 to 9 weeks or no more than 6 months to produce enough antibodies to sensitize the pregnant mother. Once sensitized, it is impossible to return to the unsensitized state. This woman is still RhD-positive if she is pregnant with a second child. After the red blood cells enter the mother again in the uterus or at birth, the sensitized pregnant mother quickly produces a large amount of IgG antibodies, which pass through the placenta to the fetus, causing the fetus or newborn to occur. Hemolytic disease, the more births, the more severe the hemolytic disease. There are very few Rh-negative people in China, so the incidence of RhD hemolytic disease is much lower than in Europe and the United States.

an examination

Related inspection

Infertility blood type examination blood type identification blood type identification

(1) Prenatal diagnosis

Check the blood type of pregnant women and husbands. Pregnant women check serum antibodies at the 16th week of pregnancy, as a basal level, and then measure the antibody at 28 to 30 weeks, and then measure once a month. If the antibody titer rises, it may indicate that the fetus may be affected. At the 28 to 31 weeks of pregnancy, the ratio of amniotic fluid bilirubin to amniotic fluid lecithin (L) sphingomyelin (S) should be measured simultaneously; if L/S 2, it indicates that the fetal lung is mature, and conditional delivery is considered.

The Rh-negative pregnant women were tested by PCR for the gene of fetal RhD blood type in amniotic fluid. The DNA of fetal RhD could also be directly detected from the venous blood of pregnant women by fluorescent PCR to determine the blood type of the fetus.

(two) birth time diagnosis

Check the blood type and specific antibodies of the fetal umbilical cord blood.

(3) Postpartum diagnosis

1. Blood routine examination: the number of red blood cells and hemoglobin decreased, the reticulocytes can be increased to 5% to 6%, and the red blood cells can reach 2 to 10/100 white blood cells within 1 to 2 days after birth.

2. Serum total bilirubin increased, mainly unconjugated bilirubin.

3. Blood type and blood antibody test

(1) ABO hemolysis: the blood type of pregnant mothers and infants are detected separately; the direct and indirect anti-human globulin test is often negative; but the "most suitable dilution anti-human globulin serum" for "antibody release test" can give positive results. .

(2) Rh hemolytic disease: detection of pregnant female and infant Rh blood type; neonatal anti-human globulin direct and indirect tests are positive; neonatal serum and standard Rh red blood cells for agglutination test, according to agglutination results to determine the presence of neonatal serum The type of Rh antibody can clearly diagnose the type of Rh hemolytic disease.

Differential diagnosis

1. Fetal edema: should be differentiated from non-immune fetal edema, especially -thalassemia, Hb Barts fetal edema syndrome, other should also consider congenital nephropathy, fetal-mother transfusion, intrauterine infection, congenital malformation, etc. Factors, these can be identified by clinical tests serological tests and the like.

2. Astragalus: Physiological jaundice appears late, slow progress, mild degree, no anemia and hepatosplenomegaly, and rare nucleated red blood cells in peripheral blood. Septicemia has symptoms of poisoning, unstable body temperature, and positive blood culture can help identify. Other congenital hemolytic diseases such as G-6-PD deficiency should also be identified.

3. Anemia: It is mainly differentiated from blood-stasis anemia caused by various causes, such as fetal-female transfusion, fetal-fetal transfusion, intracranial hemorrhage and visceral rupture.

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