ICD-10-CM > O00-O9A > O30-O48 > O35 > O35.1 > O35.13 O35.13 Maternal care for (suspected) chromosomal abnormality in fetus, Trisomy 21 Non-Billable/Non-Specific Codes O35.13X0..., not applicable or unspecifiedO35.13X1..., fetus 1O35.13X2..., fetus 2O35.13X3..., fetus 3O35.13X4..., fetus 4O35.13X5..., fetus 5O35.13X9..., other fetus