O36.1 vs O36.23X9
O36.1 (Maternal care for other isoimmunization) compared with O36.23X9 (Maternal care for hydrops fetalis, third trimester, other fetus), from the official CMS tabular data. Do not report these codes together: the official tabular list marks them Excludes1.
Can these codes be reported together?
No — do not report together. O36.23X9 carries an Excludes1 note covering O36.1: “hydrops fetalis associated with ABO isoimmunization (O36.1-)”
Sole exception: when the two conditions are documented as unrelated to each other (ICD-10-CM Official Guidelines, Section I.A.12.a).
Side by side
| O36.1Maternal care for other isoimmunization | O36.23X9Maternal care for hydrops fetalis, third trimester, other fetus | |
|---|---|---|
| Billing status | Non-billable header Report instead: O36.1110, O36.1111, O36.1112, O36.1113, O36.1114 | Billable |
| Classification | O00-O9A — Pregnancy, Childbirth and the Puerperium (O00-O9A) | O00-O9A — Pregnancy, Childbirth and the Puerperium (O00-O9A) |
| Definition | Maternal care for other isoimmunization is a non-billable ICD-10-CM category code (O36.1). | Maternal care for hydrops fetalis, third trimester, other fetus is a billable ICD-10-CM diagnosis code (O36.239). |
| 7th character | One of the following 7th characters is to be assigned to each code under category O36. 7th character 0 is for single gestations and multiple gestations where the fetus is unspecified. 7th characters 1 through 9 are for cases of multiple gestations to identify the fetus for which the code applies. The appropriate code from category O30, Multiple gestation, must also be assigned when assigning a code from category O36 that has a 7th character of 1 through 9. | One of the following 7th characters is to be assigned to each code under category O36. 7th character 0 is for single gestations and multiple gestations where the fetus is unspecified. 7th characters 1 through 9 are for cases of multiple gestations to identify the fetus for which the code applies. The appropriate code from category O30, Multiple gestation, must also be assigned when assigning a code from category O36 that has a 7th character of 1 through 9. |
| Includes | the listed conditions in the fetus as a reason for hospitalization or other obstetric care of the mother, or for termination of pregnancy Maternal care for ABO isoimmunization | the listed conditions in the fetus as a reason for hospitalization or other obstetric care of the mother, or for termination of pregnancy |
Derived from the official CMS ICD-10-CM tabular data (FY2026). Not billing advice; verify sequencing rules for the encounter. All data sources