Hemolytic Disease of the Newborn

Frequently asked questions

What are the clinico-anatomical forms of hemolytic disease of the newborn?

Three main clinical forms of hemolytic disease of the newborn are distinguished based on their frequency of occurrence:

• Icteric form — occurs most frequently (88% of cases).
• Anemic form — observed in 10% of patients.
• Hydrops fetalis — the rarest form, diagnosed in 2% of cases.

What microscopic changes are detected in the liver in hemolytic disease of the newborn?

Microscopic examination of the liver reveals abnormally high erythropoietic activity with the formation of prominent foci of extramedullary hematopoiesis. In addition, as a result of intravascular hemolysis, generalized hemosiderosis develops, characterized by the formation and accumulation of hemosiderin pigment in macrophages and Kupffer cells (hepatic stellate cells).

Which brain structures are affected in the development of kernicterus?

During the development of kernicterus, unconjugated bilirubin causes toxic damage primarily to subcortical nuclei and other specific areas of the brain. The affected structures include:

• Basal ganglia — specifically the globus pallidus.
• Thalamus and subthalamic nuclei.
• Cerebellum and hippocampi.
• Spinal cord and cranial nerves (VIII, VII, and III).
• Gray matter of the cerebral cortex — affected less frequently.

Macroscopically, these areas acquire a bright yellow coloration, and the brain itself becomes edematous.

What morphological changes occur in the spleen in hemolytic disease of the newborn?

The main macroscopic change in the spleen in hemolytic disease of the newborn is its pronounced enlargement — splenomegaly (as part of hepatosplenomegaly). Microscopically, the organ shows:

• Extramedullary erythropoiesis — the formation of foci of extramedullary hematopoiesis as a compensatory reaction to hemolysis and anemia.
• Hemosiderosis — the formation and accumulation of hemosiderin pigment in splenic macrophages due to intravascular erythrocyte destruction.

Which type of maternal antibody crosses the placenta and causes hemolysis of fetal erythrocytes?

Hemolysis of fetal erythrocytes is caused by maternal IgG antibodies. This is the only class of immunoglobulins capable of crossing the placental barrier. In the presence of maternal-fetal blood group incompatibilities (such as Rh incompatibility or ABO incompatibility), these antibodies enter the fetal circulation, bind to fetal red blood cells, and cause their destruction, leading to hemolytic disease of the newborn.

Why is jaundice more severe in premature infants?

This is due to the marked immaturity of hepatic enzyme systems, specifically the insufficient activity of glucuronyl transferase.

What is extramedullary hematopoiesis?

It is the process of blood cell formation outside the bone marrow, such as in the liver, which is a characteristic histological feature of immature fetuses.

What structures are characteristic of the fetal adrenal glands?

The fetal adrenal glands are characterized by the presence of a prominent fetal cortex, whose cells are arranged in radial cords and undergo regression after birth.