Mat care chromosomal abnlt in fetus, Trisomy 21, other fetus

This code signifies maternal care provided due to a suspected or confirmed diagnosis of Trisomy 21 (Down syndrome) in one of multiple fetuses, specifically when the affected fetus is not the primary one. It indicates that the mother is receiving specialized obstetric management because of this chromosomal abnormality in a co-twin or other non-primary fetus.

Apply this code when documentation clearly indicates maternal care for a pregnancy involving multiple gestations, and one of the fetuses, other than the designated primary fetus, has a suspected or confirmed diagnosis of Trisomy 21. This would typically be supported by genetic testing results, ultrasound findings, or other diagnostic reports.

• Ensure documentation specifies "other fetus" to differentiate from a primary affected fetus.
• Always sequence this code as a secondary diagnosis, following the code for the type of multiple gestation (e.g., O30.0-).
• Do not use this code if the chromosomal abnormality is in the primary fetus; a different subcategory of O35.13 would be appropriate.