Hemolytic disease of the newborn

Hemolytic Disease of the Newborn (HDN), also known as erythroblastosis fetalis, is a blood disorder that occurs when the blood types of a mother and her fetus are incompatible. It is a type of hemolytic anemia in newborns, primarily caused by the destruction of the fetus's red blood cells by the mother's immune system. This condition can lead to serious complications, including fetal anemia, hydrops fetalis, and even fetal death if not properly managed.

Causes

HDN is most commonly caused by incompatibility between the mother's and the fetus's blood types, specifically the Rh factor (RhD antigen). This incompatibility arises when an Rh-negative mother becomes sensitized to Rh-positive fetal red blood cells. Sensitization can occur during pregnancy or at delivery. Other blood group incompatibilities, such as those involving the ABO blood group system, can also cause HDN, but these cases are generally less severe.

Pathophysiology

The pathophysiology of HDN involves the immune response of the mother to the fetal red blood cells. When the mother's immune system encounters the foreign antigens on the fetal red blood cells, it produces antibodies against these cells. These antibodies can cross the placenta and target the fetal red blood cells, leading to their destruction (hemolysis), which in turn causes anemia and other related complications in the fetus.

Symptoms

Symptoms of HDN can vary in severity, from mild to life-threatening. Common symptoms include:

• Jaundice (yellowing of the skin and eyes)
• Anemia
• Enlarged liver and spleen
• Hydrops fetalis (severe swelling in the fetus)
• High levels of bilirubin in the blood

Diagnosis

Diagnosis of HDN involves several tests, including:

• Blood tests to determine the blood types of the mother and fetus
• Ultrasound to check for signs of anemia and hydrops in the fetus
• Amniocentesis to measure the bilirubin levels in the amniotic fluid
• Cordocentesis to directly measure the fetal blood count and bilirubin levels

Treatment

Treatment for HDN depends on the severity of the condition and may include:

• Intrauterine transfusions to treat fetal anemia before birth
• Early delivery if the fetus is at risk
• Exchange transfusions after birth to replace the newborn's damaged blood with fresh blood
• Phototherapy to treat jaundice

Prevention

Prevention of HDN is possible with the use of Rh immunoglobulin (RhIg), which is given to Rh-negative mothers during and after pregnancy to prevent sensitization to Rh-positive fetal blood cells.