Late anemia of fetus or newborn due to isoimmunization

This code signifies a delayed onset of anemia in a fetus or newborn resulting from an immune response where maternal antibodies attack fetal red blood cells. This isoimmunization typically occurs when there is an incompatibility between the mother's and baby's blood types, such as Rh incompatibility. The anemia manifests after the immediate neonatal period.

Use this code when documentation specifies a diagnosis of late anemia in a neonate or fetus, explicitly linked to isoimmunization. This often follows a history of maternal Rh sensitization or ABO incompatibility, with the anemia presenting days or weeks after birth. Supporting documentation would include laboratory results showing anemia and positive direct Coombs test, along with a clear etiology of isoimmunization.

• Differentiate from immediate or early onset anemia due to isoimmunization, which would typically be coded differently.
• Ensure the documentation clearly states "late" or "delayed" onset of anemia to justify this specific code.
• Always sequence this code as a secondary diagnosis if the primary reason for the encounter is a symptom of the anemia (e.g., jaundice, respiratory distress).