Mat care chromosomal abnlt in fetus, Trisomy 21, fetus 3

This code signifies specialized maternal care provided when a fetus is suspected or confirmed to have Trisomy 21 (Down syndrome), specifically when the pregnancy involves a third fetus (e.g., in a triplet pregnancy). It indicates the mother is receiving monitoring and management due to this fetal genetic condition.

Apply this code when documentation clearly indicates maternal care for a fetus diagnosed or highly suspected of having Trisomy 21, and the specific fetus in question is identified as the third fetus. This often follows abnormal prenatal screening results (e.g., NIPT, quad screen) or diagnostic testing (e.g., amniocentesis, CVS).

• Ensure the documentation specifies "fetus 3" to accurately assign this code; otherwise, an unspecified fetus code (O35.13X0) or a different fetus number should be used.
• Always sequence this code as a secondary diagnosis, with a code from category Z3A.- (Weeks of gestation) as the primary diagnosis, if applicable.
• Do not confuse with codes for other chromosomal abnormalities (e.g., Trisomy 18, Trisomy 13); verify the specific genetic condition.