Sir.—The widespread use of Rh immune globulin has made severe hemolytic disease of the newborn (HDN) due to Rh incompatibility a rare occurrence in contemporary pediatrics. Earlier reports describe the natural history of the Rh HDN and offer possible mechanisms to explain the associated phenomena of late anemia and occasional misleading Rh typing.1-3 We recently encountered a 7-week-old patient at Children's Hospital of Pittsburgh who had severe late anemia with prolonged misleading ABO and negative Rh typing. Our finding of anti-D antibody on bone marrow cells provides new evidence for intramedullary extravascular hemolysis in this setting.
Patient Report.—A 1950-g female infant was delivered by elective cesarean section at 34 weeks' gestation. The mother was a 27-year-old gravida 4, para 3 woman with an A Rh-negative blood type and a history of severe Rh sensitization. Her first child had A Rh-positive blood type and jaundice requiring phototherapy. Her