Rh incompatibility hemolytic disease
Introduction
Introduction to Rh blood group incompatibility RH blood type is not hemolytic disease, also known as neonatal maternal and child blood type incompatibility, refers to immune hemolytic anemia caused by blood group antibodies, it is caused by maternal and child blood group incompatibility, is neonatal hyperbilirubinemia One of the most common causes, and early onset, rapid progress, severe cases can cause jaundice. Neonatal hyperbilirubinemia caused by blood group antigens is often seen in several antigenic blood types, such as RH blood type. basic knowledge The proportion of sickness: 0.00001% Susceptible people: no special people Mode of infection: non-infectious Complications: thrombocytopenic purpura, ataxia, disseminated intravascular coagulation
Cause
Rh blood group incompatibility cause of hemolytic disease
(1) Causes of the disease
Although the placenta acts as a barrier to prevent fetal blood from entering the maternal blood circulation, a small amount of infiltration (transfusion through the placenta) can occur. Once the fetal red blood cell antigen is not in contact with the mother, the mother produces the corresponding blood group antibody, which is input into the fetus through the placenta and acts on the fetus. Red blood cells can cause hemolytic disease in newborns.
Using acid solubilization technology, fetal red blood cells appear in the blood circulation of about 1/15 of pregnant women at 3 months of pregnancy. During normal pregnancy, the amount of fetal blood entering the maternal circulation is very small, generally <0.1ml, but during childbirth. There may be >0.2ml of fetal blood entering the maternal blood circulation, which can stimulate the mother to produce antibodies. A large number of transplacental blood loss can also be seen in automatic or artificial abortion, ectopic pregnancy, cesarean section, pregnancy-induced hypertension syndrome, placenta previa, placenta Early exfoliation, etc., all of them are easy to cause maternal sensitization to fetal red blood cells. For parents with ABO blood group incompatibility, the incidence of progeny Rh hemolytic disease is low, because the main blood group antigen does not cooperate, so that fetal blood is quickly taken in the mother body. Destruction by anti-A or anti-B lectin reduces the sensitization of Rh antigen and reduces the chance of Rh hemolysis.
(two) pathogenesis
The excretion of bilirubin mainly relies on the form of binding to glucuronidase, the lack of glucuronyltransferase in neonates, especially premature infants, the reduction of glucuronide bilirubin, and the lack of YZ2 transporter, which makes bilirubin The transfer of hepatocytes to the biliary system is a cause of increased blood bilirubin.
When the Rh blood group is incompatible, the fetal red blood cells entering the mother are first swallowed by macrophages. Under the action of macrophage conditioning and antigen presentation, it takes a considerable time to release a sufficient amount of Rh antigen, and then stimulate the corresponding lymphocytes. The anti-Rh antibody is produced. This secondary immune response develops slowly. It takes 2 to 6 months. The mother's first anti-DIgM is low in content, short in existence, unable to pass through the placenta, and does not pose a threat to the fetus. When the primary reaction is pregnant again, it can quickly produce secondary IgG antibodies, which cause hemolysis by fetal placenta destruction. In the four subtypes of IgG, anti-D antibodies of IgG1 and IgG3 are most common, such as two. When they are present at the same time, they often have severe hemolysis.
Rh hemolytic disease occurs in the first child. It is usually only seen in the mother who has received blood group incompatibility before the pregnant mother or pregnant mother Rh positive, so that the pregnant mother has an initial reaction against anti-Rh positive antibody in the fetus, when she is pregnant Rh In a positive fetus, a secondary immune response can occur quickly, resulting in fetal hemolysis, the so-called grandmother theory proposed by Taylor.
Rh blood group incompatibility is mainly seen when the fetus is Rh positive and the mother Rh is negative, but it can also occur when the mother is Rh positive. If the mother is ee, cc, and the fetus is E or C, the mother can produce anti-E or anti-C antibody. Among the Chinese Han population, RhCCDeeCcDee accounts for about half, and the antigenicity of RhE is second only to D. Therefore, Shanghai reported that Rh-positive Rh hemolytic disease accounts for more than 1/3 of the entire Rh hemolytic disease. Beijing Children's Hospital, 1974-1994, In the past 20 years, 71 cases of Rh hemolytic disease were treated, accounting for 4.6% of neonatal hemolytic disease, and the mother was Rh-positive hemolytic disease accounted for 1/4.
Prevention
Rh blood group incompatibility prevention
There are two purposes for the prevention and treatment of neonatal hemolytic disease:
1. Prevention of severe anemia and hypoxia caused by intrauterine or shortly after birth.
2. Avoid bilirubin encephalopathy due to hyperbilirubinemia.
Prenatal treatment: Obstetric treatment of neonatal hemolytic disease is mainly to detect which fetuses are seriously affected, to treat fetal anemia and to determine the optimal timing of delivery, when the mother Rh blood group system antibody titer 1:64 or t 0.7 g / ml When it is indicated that the fetus is seriously affected, it can prevent fetal death by intrauterine blood transfusion or early termination of pregnancy, or use plasma exchange to reduce the titer of pregnant mother blood type antibody. If the fetus has reached more than 33 weeks, amniotic fluid lecithin/sphingomyelin >2, It is suggested that the fetal lung has matured and can be considered for early delivery.
Complication
Rh blood group incompatibility complications Complications thrombocytopenic purpura ataxia diffuse intravascular coagulation
1. bilirubin encephalopathy (nuclear jaundice) The main complication of neonatal hemolytic disease is encephalopathy caused by unconjugated bilirubin to central nervous system toxicity. Unbound bilirubin degraded by heme is a kind of Polar compounds, insoluble in water, can enter the brain with such polar molecules. The damage of bilirubin to the brain is caused by its deposition in the brain, depending on the following three mechanisms:
1 Even in "physiologic hyperbilirubinemia", bilirubin can continuously pass through the blood-cerebrospinal fluid barrier, but most do not cause permanent nerve damage.
2 Under pathological conditions, plasma free bilirubin increased significantly, resulting in a significant increase in bilirubin entering the central nervous system, bilirubin combined with nerve cells, resulting in deposition of brain tissue.
3 Some factors such as sepsis, hypoxia, fever and acidosis can further damage the blood-cerebrospinal fluid barrier and increase the penetration of bilirubin into the brain. The term nucleoside jaundice is that the basal ganglia and cerebellum are stained yellow by bilirubin. Come, the clinical symptoms of encephalopathy often appear 2 to 5 days after birth, but also in later periods. Early symptoms include anorexia, restlessness, decreased muscle tone, apnea and hug reflexes, etc. Screaming, squatting and angulation, followed by irregular breathing and pulmonary hemorrhage often lead to death. Survivors may have persistent sequelae such as sensorineural deafness, dyslexia, language impairment, and severe cerebral palsy. Mental retardation, ataxia, and dyskinesia, from hyperbilirubinemia to bilirubin encephalopathy can be divided into four phases:
1 aura period.
2 period.
3 recovery period.
4 sequelae, bilirubin encephalopathy in premature and low birth weight infants often lacks typical sputum symptoms.
2. In a few other cases, thrombocytopenic purpura and disseminated intravascular coagulation can occur.
3. In severe cases, hypoglycemia may be associated with increased blood insulin levels. Hypoglycemia may increase damage to the central nervous system and increase toxic effects of bilirubin, and should be monitored regularly and appropriate treatment.
Symptom
Rh blood group is not hemolytic disease symptoms Common symptoms Immunological hemolytic pleural effusion ascites jaundice fetal edema heart failure severe anemia
All clinical manifestations depend on the rate of fetal red blood cell destruction and the degree of compensatory erythropoiesis. In light cases, there is only a small amount of hemolysis. In severe cases, fetal edema syndrome can cause intrauterine death. Generally, the heavier the anemia, the more severe the clinical manifestation. The risk of brain damage caused by hyperbilirubinemia is also greater.
Huang Wei
Even if there is a hemolytic disease in the newborn, there is no jaundice at birth. Once the newborn has jaundice on the first day of birth, the possibility of hemolytic disease of the newborn must be considered. Serological examination should be performed immediately to confirm the diagnosis. Rh hemolytic disease Astragalus appears early and to a greater extent.
2. Immunological hemolysis and anemia
Phenobarbital can increase glucuronyltransferase activity and increase bilirubin binding protein content. Prenatal or neonatal phenobarbital can increase bilirubin clearance rate and lower blood bilirubin content. .
Patients have immune hemolysis, the degree of anemia depends on the balance of hemolysis process and red blood cell balance of bone marrow. At birth, most newborns have only mild anemia, liver and spleen can be slightly enlarged, such as anemia, liver and spleen enlargement Gradually, congestive heart failure, edema, ascites, and pleural effusion can occur in severe anemia, which constitutes a fetal edema syndrome, most of which die several hours after birth, and the severe ones die in the uterus.
Examine
Rh blood type incompatibility examination
1. The degree of peripheral blood anemia, reticulocyte increase and the appearance of nucleated red blood cells are proportional to the degree of hemolysis, blood smear can be seen polychromatic, red blood cell size and nucleated red blood cells, Rh hemolysis, spherical red blood cells It is not uncommon to see that white blood cells increase and the left side of the nucleus is seen when hemolysis is severe.
2. The bone marrow image mainly shows excessive proliferation of the red blood cell line.
3. Immunological examination The main basis for postpartum diagnosis is the examination of serum-specific immune antibodies. Rh hemolytic disease is caused by IgG anti-Rh antibody produced by mother. The antibody is from the serum of the mother, not the serum of the sick child. Therefore, it should be used as much as possible. Mother's serum is checked, including the following four aspects:
(1) Check if the mother's Rh blood type is different.
(2) Check whether the red blood cells of the baby are sensitized. The positive anti-human globulin test indicates that the baby red blood cells are sensitized by the blood group antibody, and further release test to find out which type of blood type antibody.
(3) Checking the presence and type of blood group antibodies in infant serum, and indirect testing of infant serum with various standard red blood cells as anti-human globulin. Positive results indicate the presence of blood group antibodies and inferring the type of antibodies, (4) Check the presence or absence of Rh blood group antibodies in maternal serum. Positive patients have reference significance for diagnosis. Once newborn Rh positive and mother Rh negative and direct anti-human globulin test positive, a few Rh hemolytic patients have Rh positive. (D positive), but anti-E, c, C and other antibodies exist.
4. Serum bilirubin examination In the fetal period, bilirubin can pass through the placenta, so umbilical blood bilirubin is not high, such as more than 3mg / dl, there may be intra-femoral anemia, lost placenta to remove bilirubin after birth The ability to increase the blood bilirubin content in neonates rapidly, and its increasing speed and absolute value constitute an important indicator for predicting bilirubin encephalopathy. Therefore, the changes of serum bilirubin content should be closely monitored at this time, according to Beijing Children's Hospital. In the case of indirect bilirubin increase, high direct bilirubinemia may occur, which is considered as the result of cholestasis; while direct bilirubin >4mg/dl should be alert to the possibility of developing ketosis after phototherapy, most directly Increased bilirubin returned to normal in the short term.
According to the condition, clinical manifestations, symptoms, signs, X-ray, B-ultrasound, electrocardiogram, biochemical examination.
Diagnosis
Diagnosis and identification of Rh blood group incompatibility
According to the condition, clinical manifestations, symptoms and signs, X-ray B-ultrasound, electrocardiogram and biochemical laboratory examination can be used to confirm the diagnosis.
