Pathogenesis And Clinical Presentation Of Hemolytic Disease Of The New Born
Phototherapy On A New Born
Hemolytic Disease Of The New Born
The newborn may suffer from Rh incompatibility or ABO incompatibility if there is Rh or ABO incompatibility between the parents.
Rh incompatibility: This accounts for the vast majority of isoimmune hemolytic anemias of the newborn and manifests as jaundice on the first day of life. Among the Rh antigens ‘D’ is most antigenic and this is involved in Rh incompatibility. In India for instance, 8% of population is Rh negative, unlike in the west where the frequency is 15%. About 17% of Rh negative women get immunized during pregnancy if the fetus is Rh positive.
The Rh isoimmunisation occurs when an Rh negative individual receives Rh positive blood by transfusion or by other sources. When an Rh negative mother carries an Rh positive fetus, there is risk of transplacental entry of small quantities of fetal blood into the maternal circulation during the last weeks of pregnancy and during labour. Therapeutic obstetric procedures increase the risk. The fetal cells immuise the mother, and antibodies are produced depending upon the amount of transplacental hemorrhage. The ABO incompatibility between the mother and the baby protects against Rh immunization. Usually, the first born child escapes unless the mother is previously sensitized due to Rh incompatible blood transfusions during childhood or due to previous abortions. With successive pregnancies and abortion, the antibody titer in the mother progressively rises. The maternal antibodies pass back into the fetus and lead to hemolysis of fetal erythrocytes, resulting in hemolytic disease of the newborn. Severity of hemolysis depends upon the amount of maternal antibody and the period of gestation at which the fetus is affected.
The unconjugated bilirubin formedby hemolysis is bound to albumin, but when the bilirubin level exceeds 20 mg/dl, the unbound bilirubin passes to the CNS and causes damage, which is most pronounced in the basal ganglia.
The mild form manifests as moderate hemolytic anemia in the first few days of life. Hepatosplenomegaly may be just detectable. The moderately severe form presents as ‘icterus gravis neonatorum’. This leads to jaundice. Anemiamay progress and lead to cardiac failure. Hepatosplenomegaly may be more evident. Neurological abnormalities develop in severe cases. In acute form, it is characterized by a high pitched cry, opisthotonus and convulsions. Choreoathetosis, deafness, cerebral palsy and mental deficiency develop as the child grows. The neurological complications are collectively known as Kernicterus.
The severe form manifests as hydrops fetalis. Usually, the affected baby is born dead or it dies soon after birth. Gross edema, hepatosplenomegaly, anemia and effusions into serous cavities are the common stigmata.
© 2014 Funom Theophilus Makama