What is “maternal and child blood group incompatibility”?
The mother and child blood type does not merge is not scary, what is scary is the resulting “neonatal hemolysis” in some patients, for the fetus in the womb to worry about “fetal hemolysis edema, fetal death in the womb” (of course, not all maternal and child blood type incompatibility will cause fetal, neonatal hemolysis, so big skin do not just give yourself a “doctor”, scare yourself). (Of course, not all maternal and fetal blood type incompatibility will cause fetal and neonatal hemolysis, so Dapi should not just make himself a “doctor” and scare himself). Simply put, if the fetus inherits blood group antigens from the father that the mother does not have, the fetal red blood cells enter the mother’s body and cause the mother to produce the corresponding antibodies, which then enter the fetus through the placenta, resulting in an immune response to the antigens and antibodies and fetal hemolysis occurs. The causes of hemolysis in China are mostly concentrated in ABO blood group incompatibility, RH blood group incompatibility accounts for a small proportion, and MN blood group incompatibility is rare.
II. “MN system” blood group
There are three MN blood groups in humans: M, N, and MN. anti-M antibodies are a fairly common natural antibody, and can be detected in about 10% of pregnant women. Anti-M antibodies are mainly IgM antibodies. In most cases anti-M antibodies are inactive at 37°C, rarely cause hemolytic transfusion reactions or neonatal hemolytic disease (usually with a prevalence of about 1/1000), nor do they cross the placental barrier and are generally not clinically significant.
Of course there are always accidents, to give a simple example.
Mother: type B, RH (+), NN
Father: Type B, RH(+), MN
Fetus: Type B, RH(+), MN
Further examination revealed that
Mother: IgM anti-M (+), IgG anti-M (+)
Fetus: IgG anti-M (+)
This is one of the combinations of potential “neonatal hemolysis”.
When is it necessary to test the MN system?
Anti-M antibodies are not uncommon, but the incidence of severe neonatal hemolytic disease is very low. Therefore, testing for the MN system is not part of routine blood testing and is never recommended as a routine test. However, to rule out chromosomal and immunological factors, patients with recurrent stillbirths of unknown origin, miscarriage, fetal edema, severe fetal anemia, and to rule out ABO and RH blood group system abnormalities, perhaps this direction is a breakthrough to try.
What are the feasible tests?
The following tests are available after evaluation by the physician: irregular antibody test, MN antibody screen, anti-M antibody titer (but there is no evidence that anti-M antibody titer can predict the severity of hemolysis), Coombs’ test (it should be noted that there have been case reports of neonatal MN systemic hemolysis with negative Coombs’ test). ‘ tests are negative).
It’s a simple matter of “you can check but the results are not guaranteed to be useful”. Tu Xiaomed can only say, science can explain the mystery of life is really limited, the cure is not as pure as “yes” and “no”, many times we have to “take one step and see”. “We have to take one step at a time.
Fetal monitoring
For pregnant women diagnosed with MN blood group incompatibility, fetal monitoring is similar to that for patients with other blood group system incompatibility.
1. Fetal umbilical vein puncture can accurately understand the degree of anemia and blood type of the fetus.
2. Fetal ultrasound monitoring can be used to monitor and predict the severity of fetal anemia and hemolysis. Ultrasound indicators include: growth and development indicators, blood flow spectrum, peak systolic blood flow in the middle cerebral artery of the fetus, etc.
3. Intrauterine fetal safety assessment: ultrasound, fetal heart monitoring, etc.
Treatment
For pregnant women diagnosed with MN blood group incompatibility, the treatment is similar to that for patients with other blood group system incompatibility.
1. Intrauterine blood transfusion: If the child with anti-M antibody (+) chooses M antigen-negative ABO homozygous or O RH(-) blood. Preferred transfusion is via fetal hepatic vein or umbilical vein, in addition to fetal intraperitoneal transfusion.
2.Intrauterine transfusion of immunoglobulin IVIG: It has been reported that intrauterine transfusion of IVIG can reduce the destruction of fetal red blood cells.
3, maternal high-dose IVIG: High-dose IVIG can inhibit maternal IgG production, but this treatment is expensive and the therapeutic effect is unclear.
4.Maternal plasma exchange: It has some effect, but it is expensive and blood products are precious.
5.The umbilical cord should be clamped immediately after delivery of the fetus: to avoid excessive inflow of umbilical cord blood into the child’s body, resulting in the entry of more allergenic red blood cells and antibodies, leading to aggravation of hemolysis.
6. Terminate the pregnancy at the right time, do not let nature take its course.
So what difficulties will this patient encounter in her next pregnancy, and how can we overcome them? At present, our Reproductive Immunology Department has been actively communicating with doctors from our Fetal Medicine Department and Blood Bank to study various plans. When our patient is well adjusted and ready to welcome a new life again, we hope that the joint protection of our hospital’s multi-disciplinary departments can bring miracles to patients with recurrent miscarriage again.