Early Hyporegenerative Anemia Complicating Hemolytic Disease of the Newborn Secondary to Rhesus Alloimmunization.

Rhesus hemolytic disease of the newborn is rarely found after the implementation of anti-D immunoglobulin prophylaxis. However, it may lead to cholestasis, elevated liver transaminases, hyperbilirubinemia, kernicterus, iron overload, and hyporegenerative anemia. Hyporegenerative anemia is characterized by low hemoglobin and reticulocyte count. It is typically recognized two to six weeks after birth. The etiology of this type of anemia is not identified yet, and treatment is controversial. We report a case of a neonate with rhesus hemolytic disease of the newborn with early hyporegenerative anemia that was noted on day seven of life. The available literature has described a similar age of onset, but after two weeks of life and not as early as on day seven of life as in our case. We treated this type of anemia with the standard of care management that includes phototherapy, intravenous immunoglobulin, and blood transfusions.