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the presence of erythroblasts in the circulating blood; called also erythroblastemia. adj., adj erythroblastot´ic.
erythroblastosis feta´lis (erythroblastosis neonato´rum) a blood dyscrasia of the newborn characterized by agglutination and hemolysis of erythrocytes and usually due to incompatibility between the infant's blood and that of the mother. In most cases the fetus or infant has Rh-positive blood and its mother has Rh-negative blood (see rh factor). Another form is seen when the fetus or infant has blood of type A or B and the mother has blood of type O; it is much milder than the Rh type because anti-A and anti-B antibodies only occasionally cross the placenta. Called also hemolytic disease of the newborn.

In Rh incompatibility the mother builds up antibodies against the red blood cells of the fetus; these pass through the placenta, enter the fetal circulation., and proceed to rapidly destroy the fetal red blood cells. In order to compensate for this, there is an ever-increasing effort on the part of the fetus to avoid anemia. This results in the release of very immature red blood cells (erythroblasts). Thus an extremely high percentage of fetal erythrocytes are erythroblasts, giving the condition its name of erythroblastosis.
Symptoms. If it survives under these circumstances, at birth the baby is jaundiced and usually anemic. The immune bodies from the mother's blood usually circulate in the baby's blood for 1 to 2 months after birth, continuing the destruction of red blood cells unless an exchange transfusion is done. Other symptoms depend on the number of red cells destroyed and the amount of damage done to other tissues of the body, such as the brain and central nervous system.
Treatment. The usual treatment for erythroblastosis fetalis is exchange transfusion in which the infant's blood is replaced with Rh-negative blood. This measure stops the destruction of the infant's red blood cells, and gradually the Rh-negative blood is replaced with the baby's own blood. In about 6 weeks the immune bodies left over from the mother's blood have been destroyed and are no longer a menace to the baby. Exposure to ultraviolet light (phototherapy) breaks down the bilirubin causing the jaundice and reduces the number of transfusions that are required.ƒ

Developments in the management of erythroblastosis include amniocentesis and intrauterine fetal transfusion. The former is puncture of the amniotic sac through the maternal abdomen and is done for the purpose of obtaining a sample of amniotic fluid for analysis. This allows for determination of concentration of bilirubin pigments and protein in the amniotic fluid; a high concentration indicates excessive destruction of fetal erythrocytes. If there is a mild hemolysis the mother is watched closely and allowed to deliver at term. In more severe cases, induced labor and premature delivery are usually advised so that further destruction of erythrocytes will not take place and an exchange transfusion can be performed as soon as possible. For cases of very severe hemolysis it has been recommended that an intrauterine transfusion be administered to the fetus. This is a delicate procedure that involves certain risks, and is advised only if the mother's past history and the present evidence indicate that the infant would not survive or would suffer damage from erythroblastosis.


The presence of nucleated red cells in the peripheral blood.
[erythroblast + G. haima, blood]


The presence of nucleated red blood cells in peripheral blood.
Synonym(s): erythroblastaemia.
[erythroblast + G. haima, blood]