Delayed hemolysis, also known as late-onset hemolysis, sometimes occurs in newborns affected by hemolytic disease of the fetus and newborn (HDFN).
This is due to maternal antibodies that attack the baby’s red blood cells following birth. Hemolysis leads to anemia and may occur two to 12 weeks after delivery, and once detected, should be treated immediately to avoid complications that could have long-term consequences.
What is HDFN?
Hemolytic disease of the fetus and newborn (HDFN) is an immune-mediated red blood cell disorder that occurs when a baby’s RBCs break down quickly, which is called hemolysis. HDFN is caused by a mismatch between a mother’s and her baby’s blood type (A, B, AB, or O) or Rhesus (Rh) factor (Rh-positive or Rh-negative) during pregnancy.
What is hemolysis?
Hemolysis in HDFN is the breaking down of the baby’s red blood cells (RBCs). It occurs when the mother’s immune system produces antibodies against her baby’s RBCs as the result of a blood type incompatibility. They cross the placenta and progressively destroy the baby’s RBCs, resulting in anemia.
The baby’s liver is immature and therefore has difficulty in processing and eliminating the bilirubin that is produced when RBCs break down. This causes bilirubin to accumulate, causing jaundice and dangerous complications if not treated urgently.
Learn more about HDFN causes and risk factors
Acute hemolysis versus delayed hemolysis
Acute hemolysis, or early onset hemolysis, resulting from HDFN is detected immediately following delivery, with the newborn showing symptoms of pale skin, jaundice, severe swelling of the body, limpness and breathing difficulties.
Delayed hemolysis can appear later if maternal antibodies are not eliminated from the newborn’s bloodstream. Maternal antibodies can bind to the newborn’s RBCs and remain for up to 12 weeks. This means that a newborn can develop hemolysis and its associated symptoms in the first 2-12 weeks of life.
Detection of delayed hemolysis
If symptoms such as jaundice, pale skin, fussy feeding, fatigue, limpness persist or worsen in the first few weeks, this may be an indication that delayed hemolysis is developing.
A diagnosis of delayed hemolysis is made by testing the newborn’s blood to measure levels of bilirubin, hemoglobin and maternal antibodies as well as a red blood cell count and a reticulocyte count to evaluate anemia.
Treatment of delayed hemolysis
As the red blood cells break down, the resulting symptoms are anemia and jaundice. They can have potentially life-threatening consequences if left untreated, such as kernicterus which can cause brain damage. It is therefore essential that anemia and jaundice are treated with phototherapy, blood transfusions and exchange transfusions in severe cases. Intravenous immunoglobulin may also be considered to slow the breakdown of the newborn’s RBCs.
Follow up post-discharge
It is possible for a newborn to be discharged from hospital, and then to be readmitted with delayed hemolysis or anemia. Regular follow-up appointments after you are discharged from the hospital will help your doctor monitor you for late-onset hemolysis and associated anemia and provide urgent treatment if required.
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