1.What is Rh hemolytic disease?
Rh hemolytic disease of the newborn is a hemolytic disease caused by a mismatch between the blood type of the mother and the fetus, which can cause fetal red blood cell destruction. Rh hemolytic disease can also cause jaundice (yellowing of the skin and eyes), anemia, brain damage, heart failure, and even death in newborns, but it does not affect the mother’s health.
In the United States, about 20,000 babies with Rh hemolytic disease are born each year, although the number of newborns with Rh hemolytic disease each year has decreased significantly since 1968, when preventive treatment for Rh hemolytic disease became available. However, not all pregnant women who need prophylactic treatment have access to it, so there is still a small percentage of pregnant women who do not benefit from this technology. As a result, about 4,000 babies with Rh hemolytic disease are still born each year.
2. What are the causes of Rh hemolytic disease?
Most people in the population have Rh-positive blood type with Rh antigen, an inherited protein on the surface of red blood cells. Approximately 15% of Caucasians and 7% of African Americans in the United States do not have the Rh antigen, or Rh-negative blood type. people with Rh-negative blood type do not have any health problems per se, but if a woman has Rh-negative blood type, she is at risk of delivering a baby with Rh hemolytic disease.
The offspring of a mother with Rh-negative blood type and a father with Rh-positive blood type are at risk of inheriting the father’s Rh-positive blood type and being at risk at birth, especially during delivery, when some Rh-positive red blood cells of the fetus may enter the mother’s blood, and these fetal red blood cells with Rh antigens are foreign to the mother’s organism, and the mother’s body tries to produce antibodies against Rh by This initiation of the maternal immune response is called sensitization.
In the first pregnancy, the risk to the fetus with Rh-positive blood type is minimal because the child is usually born before the mother develops sensitization, or at least before the mother produces the appropriate amount of Rh antibodies. However, once sensitization has occurred, the mother continues to produce Rh antibodies as part of her blood throughout her life. In each subsequent pregnancy, the mother’s Rh antibodies are then able to reach the fetus through the placenta, so with each subsequent pregnancy, the child is at increasing risk of developing severe Rh hemolytic disease. If the fetus is Rh-positive, the mother’s Rh antibodies can destroy the fetus’ red blood cells and cause Rh hemolytic disease in the baby.
3. How can a woman find out if she has an Rh-negative blood type?
A simple blood test can check if a woman is Rh-negative. Every woman should be tested early in her pregnancy or before she becomes pregnant to know if she has an Rh negative blood type.
4. How to prevent Rh hemolytic disease?
To prevent Rh hemolytic disease, all children of women with Rh-negative blood types should have an Rh blood group test at birth. All Rh-negative mothers carrying Rh-positive children should be given a pure blood Rh immunoglobulin 72 hours after delivery, which can prevent sensitization in more than 95% of women with Rh-negative blood types. However, some studies have shown that sensitization occurs in about 2% of pregnant women before delivery. Therefore, in order to prevent early sensitization, Rh immunoglobulin can be given to pregnant women at 28 weeks of gestation and after delivery.
Women with Rh-negative blood types should be given Rh immunoglobulin after spontaneous abortion, ectopic pregnancy, abortion, or importation of Rh-positive blood. In addition, Rh immunoglobulin should also be injected after amniocentesis and fetal chorionic villus biopsy.
5. How does Rh immunoglobulin work?
Rh immunoglobulin contains antibodies against Rh substances that quickly adhere in the mother’s blood and help destroy and remove Rh-positive fetal cells. In this way, the mother’s body does not produce antibodies against Rh-positive fetal red blood cells because the mother has already cleared the Rh-positive fetal red blood cells prior to sensitization or rejection of the body.
The protection provided by Rh immunoglobulin lasts for only 12 weeks, and therefore Rh immunoglobulin needs to be administered again for each pregnancy and for the various conditions mentioned above.
6. Does Rh immunoglobulin treatment always work?
No. For women with Rh-negative blood type who have already been sensitized (i.e. their bodies have developed antibodies to Rh-positive blood type) due to pregnancy, spontaneous abortion, miscarriage or blood transfusion, further Rh immunoglobulin injections are not effective. A blood test can confirm whether a woman with Rh-negative blood type has been sensitized.
7. Is there a way to remove Rh antibodies from the mother’s body?
No. A woman with Rh-negative blood type can have no symptoms of disease and remain healthy, but she can continue to produce Rh antibodies as part of her blood. If she conceives a child with Rh-positive blood type, the children may develop Rh hemolytic disease.
8. How can Rh hemolytic disease be treated before the fetus is born?
When the mother has developed antibodies in her body, the father of the child should also be tested. If the father is Rh-negative, then their child will also be Rh-negative (this fetus will not be at risk for Rh hemolytic disease), and then the pregnant woman will not need further testing. If the father is Rh-positive (or if his Rh blood type is unknown), the doctor will perform an amniocentesis on the sensitized mother – a needle is inserted into the mother’s abdomen to remove the amniotic fluid to test for the fetus’ Rh blood type. There is currently a maternal blood test being tested that shows promise for determining the fetal Rh blood type in order to eventually reduce the need for amniocentesis, which still carries a small risk of miscarriage. If the fetus is Rh-positive (or if the physician does not perform an amniocentesis and does not know the fetus’ Rh blood type), then the maternal and child health staff will test for levels of Rh antibodies in the pregnant mother during the different trimesters. If antibody levels are high, the doctor will recommend special tests to determine if the child has Rh hemolytic disease.
These tests include amniocentesis and fetal umbilical vein puncture, in which a doctor, under ultrasound guidance, punctures a very fine needle into the mother’s abdomen and into the microvessels of the umbilical cord to obtain a sample of fetal blood. These tests help determine whether the fetus is anemic and the severity of the anemia. Both tests usually need to be repeated every 2-4 weeks and therefore carry a small risk of miscarriage. Recent studies have shown that an ultrasound test that measures blood flow in the arteries of the fetal head can more accurately determine whether the fetus has moderate-severe anemia (requiring prenatal treatment) or mild anemia (usually not requiring treatment). If this ultrasound, which poses no risk to the fetus, proves to be accurate, it will ultimately reduce the need for amniocentesis and umbilical venipuncture to monitor the risk of fetal Rh disease.