Hemolytic Disease of the Newborn

What are the clinical and anatomical forms of hemolytic disease of the newborn?

There are three main clinical forms of hemolytic disease of the newborn, depending on their frequency of occurrence. These include:

• Icteric form — occurs most frequently (88% of cases).
• Anemic form — observed in 10% of patients.
• Hydrops form — the rarest, 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 pronounced foci of extramedullary hematopoiesis. Furthermore, as a result of intravascular hemolysis, generalized hemosiderosis develops, which is characterized by the formation and accumulation of hemosiderin pigment in macrophages and Kupffer cells (stellate macrophages of the liver).

Which structures are damaged in the brain during the development of kernicterus?

During the development of kernicterus, toxic damage by unconjugated bilirubin primarily affects the subcortical nuclei and other specific areas of the brain. The following affected structures are distinguished:

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

Macroscopically, these areas acquire a bright yellow coloring, 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 following changes occur in the organ tissue:

• 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 the intravascular destruction of red blood cells.

Which type of maternal antibodies crosses the placenta and causes hemolysis of fetal red blood cells?

Hemolysis of fetal red blood cells is caused by maternal IgG antibodies. This is the only class of immunoglobulins capable of crossing the placental barrier. In the event of antigenic differences between mother and fetus (e.g., in Rhesus incompatibility or ABO incompatibility), these antibodies enter the fetal bloodstream, bind to its red blood cells, and cause their destruction, leading to the development of hemolytic disease of the newborn.