Rh disease

Rhesus incompatibility ( synonym: Rh incompatibility, Rhesus incompatibility) is a blood group incompatibility against Rh factor antigen "D" between Rh -negative ( Rh, rh genotype dd) mother and Rh -positive (Rh , Rh genotype Dd, dD, DD) child.

It can lead to the dissolution of childish red blood (erythrocytes) (hemolysis ). In severe cases, a hemolytic disease of the newborn with hydrops fetalis developed.

Epidemiology

In Europe, about 15 % of all people Rh - negative ( dd, always homozygous ), 50 % heterozygous (Dd ) and the remaining 35 % homozygous rhesus - positive ( DD). This results in approximately one in ten pregnant a constellation in which the Rh negative mother and the fetus is Rh -positive.

  • If the mother is Rh negative and the father is homozygous rhesus - positive, then each fetus is heterozygous Rh -positive.
  • If the mother is Rh negative and the father is heterozygous rhesus - positive, the fetus has a 50 % probability of heterozygous Rh - positive, with 50 % probability of Rh - negative.

Pathogenesis

During pregnancy occurs over no fetal blood in the maternal circulation in general. Therefore, the mother will not initially immunized at first pregnancy, it does not form anti-D antibodies and the first child stays healthy. But while the birth occurs mostly for mixing childlike and maternal blood, after which the mother is sensitized and produces antibodies against the Rh antigen. Sensitization can also be carried out also in previous miscarriages or blood transfusions. The now existing immune memory resulting in a further pregnancy for renewed and increased formation of anti-D antibodies ( booster ). This can occur (after T- cell help and immunoglobulin class switching of anti- D antibodies from IgM to IgG ) through the placenta into the child's circulation and bind to the Rh -positive erythrocytes of the child. Such laden with antibodies blood cells are broken down prematurely in the spleen of the fetus. This leads to a hemolytic anemia with hypoxia and acidosis, albumin synthesis is reduced, it develop fetal edema, pleural effusions and hydrops. Hemolysis leads to compensatory increased formation of blood cells outside the bone marrow ( extramedullary hematopoiesis ) in liver and spleen. Another form of maternal intolerance to blood cells of the unborn child are the fetal and neonatal alloimmune thrombocytopenia is (F / NAIT ) and neutropenia (F / NAIN ), in which childlike platelets or white blood cells are destroyed.

Prophylaxis

A blood group determination in early pregnancy is one of the usual prenatal care measures. All Rh -negative mothers receive prophylactic in the 28th week of pregnancy and no later than 72 hours after the birth of a Rhesus positive baby a gift of rhesus antibodies ( anti-D immunoglobulin). An antibody formation remains from so and follow pregnancies are not at risk. An anti - D prophylaxis is necessary with rh- negative pregnant women also after amniocentesis ( amniocentesis ), chorionic villus sampling, abdominal trauma and bleeding of the placenta. In addition, all rh- negative women have received such prophylaxis after an ectopic pregnancy, a rhesus -incompatible blood transfusion, miscarriage and abortion. In addition, antibody screening tests are performed in pregnancy, to satisfy them rhesus antibodies. If their concentration during pregnancy or the fetus in the ultrasound shows already signs of an incipient hydrops, intrauterine blood transfusion may optionally already be made.

Symptoms

Because of improved preventive measures, about half of newborns with a rhesus incompatibility upon evidence of rhesus antibodies have only a mild hemolysis with mild jaundice. The other part has a more pronounced anemia in general and due to the compensatory increase in blood formation outside the bone marrow an enlarged liver and spleen ( hepatosplenomegaly ). Jaundice runs correspondingly heavier, the children often come into the world already yellow ( jaundice gravis et praecox ). Generalized fluid retention (edema) and bruising in the chest and abdominal cavity ( pleural effusion and ascites) can be found in the frame of hydrops fetalis.

Diagnostics

Crucial for the diagnosis is a blood group determination of mother and child. For the detection of common placental IgG antibodies in maternal serum is the indirect Coombs test, whereas antibodies are detected on the red cells of the child with the direct Coombs test. To assess the degree of severity and the planning of further treatment further comprises determining a blood picture of the child, different hemolysis parameters ( LDH, reticulocytes ) and the bilirubin is required.

Therapy

In half of the children with mild symptoms no treatment is necessary or sufficient phototherapy. In severe cases, however, a blood exchange transfusion may need to be performed. Hydrops fetalis is for neonatologists always an emergency that already in the delivery room attracts a variety of intensive care measures by themselves. In general, the children must be immediately intubated and artificially ventilated immediately receive blood transfusions and the effusions in the chest and abdominal cavities are punctured to relieve.

Swell

  • Neonatology
  • Obstetrics and Gynecology
  • Hematology
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