Patient's question:
Doctor: Hello! We've been married for almost four years. Before marriage, we didn't plan to have children for the first two years. Now we're both thirty. In early 2004, my wife got pregnant, but it ended in a miscarriage after two months. At the time, we went to the hospital for a check-up, but the doctor said to wait until the next pregnancy before doing any tests, as each pregnancy is different, and we couldn't get pregnant again for at least a year.In July 2005, my wife got pregnant again. We were very cautious and went to the hospital for a check-up. The doctor only did a urinalysis to confirm the pregnancy and mentioned some things to pay attention to during pregnancy. We wanted to ask more questions, but the doctor said impatiently, "It's nothing."
Doctor's answer:
Hello: Hemolytic disease of the newborn (HDN) is caused by incompatibility between the blood types of the mother and fetus, where the mother's blood antibodies cross the placenta and lead to the destruction of red blood cells in the fetus or newborn. There are 26 human blood group systems, and although HDN can occur in multiple systems, ABO and Rh incompatibility are the most common causes. In Shanghai, a total of 835 cases of HDN were confirmed over 18 years, with 85.3% due to ABO incompatibility and 14.6% due to Rh incompatibility. Among hemolytic diseases caused by maternal-fetal blood type incompatibility, ABO incompatibility is the most common, primarily occurring when the mother is type O and the fetus is type A or B. Type O women naturally produce anti-A and anti-B antibodies of the IgG class, while A or B type mothers primarily produce IgM antibodies. This means the first child can be affected. The symptoms of ABO hemolytic disease are generally milder than those of Rh hemolytic disease. Jaundice is the main symptom, appearing early, often within 24 hours after birth, and progressing rapidly. The skin appears bright yellow, known as "jaundice," and serum bilirubin levels are often >255 μmol/L (15 mg/dL) and occasionally exceed 340 μmol/L (20 mg/dL). Mild anemia and hepatosplenomegaly may accompany, while fetal hydrops is rare. Laboratory tests commonly show the following abnormalities:1. Complete Blood Count (CBC): Hemoglobin levels vary in severity, with reticulocytes and nucleated red blood cells often increased.
2. Bilirubin Levels: Serum bilirubin is typically elevated, often >255 μmol/L (15 mg/dL), with an increase in indirect bilirubin.
3. Blood Type: There is often ABO incompatibility between the mother (type O) and the newborn (type A or B).
4. Immunologic Antibody Tests:
- Direct Antiglobulin Test (Coombs Test): ABO hemolytic disease is often (-) or weakly positive, while indirect Coombs test is usually positive.
- Red Blood Cell Antibody Release Test: Positive, indicating that the infant's red blood cells are sensitized.
- Free Antibody Test: Positive, indicating the presence of antibodies in the body.
- Hemolysin Test: Titer should be above 1:8.
Treatment includes:
1. Prenatal Treatment:
(1) Plasma Exchange: Performed when antibody titer exceeds 1:64, using a blood component separator to isolate maternal blood and replace it with fresh frozen plasma or albumin. This begins after 20 weeks of pregnancy.
(2) Intrauterine Blood Transfusion: Administered into the fetal abdomen to correct severe fetal anemia.
(3) Premature Delivery: If the fetus is mature, delivery may be advanced.
2. Newborn Treatment:
(1) Intravenous Immunoglobulin (IVIG): 500 mg/kg administered within 2 hours after birth to block the hemolytic process and reduce hemolysis.
(2) Phototherapy: Exposure to blue or green light.
(3) Medication: Phenobarbital is used to induce liver enzyme activity.
(4) Anemia Correction: Blood transfusion may be administered if necessary (provided the transfused blood does not carry the antigen that caused the disease).
3. Exchange Transfusion: Removes sensitized red blood cells and bilirubin.
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