Maternal care for oth rhesus isoimmun, third tri, fetus 1

This code signifies maternal care provided during the third trimester of pregnancy due to the mother developing antibodies against fetal red blood cell antigens, specifically in cases of rhesus isoimmunization other than Rh incompatibility (e.g., Kell, Duffy, Kidd). This condition can lead to hemolytic disease of the fetus and newborn (HDFN), requiring close monitoring and potential interventions.

Use this code when a pregnant patient in her third trimester is receiving care for alloimmunization to a red blood cell antigen other than the RhD antigen. Documentation should clearly indicate the specific non-RhD antibody identified (e.g., anti-Kell, anti-Duffy) and that the care is related to managing the potential impact on fetus 1.

• Ensure the documentation specifies "fetus 1" for singleton pregnancies or when identifying the affected fetus in a multiple gestation.
• Distinguish this from RhD isoimmunization, which has its own specific codes.
• Always sequence this code as a secondary diagnosis following the primary obstetric code for the encounter.