Skip to content
Dx

ICD-10-CM 2027 diagnosis code

O36.1990Maternal care for other isoimmunization, unspecified trimester, not applicable or unspecified

✓ Billable / specificRequires 7th characterMaternity · age 9–64Female only

O36.1990 is a valid, billable ICD-10-CM code for maternal care for other isoimmunization, unspecified trimester, not applicable or unspecified. It can be reported on claims for dates of service from October 1, 2026 – September 30, 2027.Short description: Maternal care for oth isoimmunization, unsp trimester, unsp

Code unchanged since ICD-10-CM took effect on October 1, 2015. Source: official FY2027 ICD-10-CM release from CDC/NCHS and CMS. Page updated September 29, 2026. About our data

About O36.1990

O36.1990 is the ICD-10-CM diagnosis code for maternal care for other isoimmunization, unspecified trimester, not applicable or unspecified. It belongs to category O36 (maternal care for other fetal problems), block O30-O48 (maternal care related to the fetus and amniotic cavity and possible delivery problems) and chapter 15 (pregnancy, childbirth and the puerperium). It is billable, so it can be reported on its own for dates of service from October 1, 2026 through September 30, 2027.

The 7th character "0" means not applicable or unspecified.

It is not a CC or MCC, so as a secondary diagnosis it doesn't change the MS-DRG severity level.

In MS-DRG v44.0, it is part of the grouping logic for DRG 817 (Other Antepartum Diagnoses with O.R. Procedures with MCC, relative weight 2.0534), DRG 818 (Other Antepartum Diagnoses with O.R. Procedures with CC, relative weight 1.2942), DRG 819 (Other Antepartum Diagnoses with O.R. Procedures without CC/MCC, relative weight 0.7739), DRG 831 (Other Antepartum Diagnoses without O.R. Procedures with MCC, relative weight 1.1558), DRG 832 (Other Antepartum Diagnoses without O.R. Procedures with CC, relative weight 0.7585) and DRG 833 (Other Antepartum Diagnoses without O.R. Procedures without CC/MCC, relative weight 0.5002), in MDC 14 (Pregnancy, Childbirth and the Puerperium), as a principal or secondary diagnosis. The DRG a claim lands in depends on the principal diagnosis, procedures and any CC/MCC secondary diagnoses.

The Medicare Code Editor treats this as a maternity diagnosis, expected only for patients age 9 through 64.

It is on the CMS list of diagnoses consistent only with female patients (the sex-conflict edit itself was retired in FY2025).

It has been part of ICD-10-CM since the code set took effect on October 1, 2015 and hasn't changed since.

Before ICD-10, this condition was coded in ICD-9-CM as 656.20 (isoimmunization from other and unspecified blood-group incompatibility, unspecified as to episode of care or not applicable).

7th character

0not applicable or unspecified

Other encounter types for O36.199:

Notes that apply from higher levels

Instructions written at a parent level also apply to O36.1990.

› From O36 Maternal care for other fetal problems
Includes
  • the listed conditions in the fetus as a reason for hospitalization or other obstetric care of the mother, or for termination of pregnancy
Excludes1
  • encounter for suspected maternal and fetal conditions ruled out (Z03.7-)
  • placental transfusion syndromes (O43.0-)
Excludes2
  • labor and delivery complicated by fetal stress (O77.-)

Broader instructions also apply from Chapter 15: Pregnancy, childbirth and the puerperium.

MS-DRG v44.0 grouping

All DRGs →

Inpatient MS-DRGs this diagnosis can group to, as the principal or a secondary diagnosis, depending on the rest of the claim.

ICD-9-CM equivalent

Converter →
  • 656.20Isoimmunization from other and unspecified blood-group incompatibility, unspecified as to episode of care or not applicableapproximate

From the CMS 2018 General Equivalence Mappings (GEMs), the final GEMs release.

Code history

  1. 2016
  2. 2017
  3. 2018
  4. 2019
  5. 2020
  6. 2021
  7. 2022
  8. 2023
  9. 2024
  10. 2025
  11. 2026
  12. 2027
  • FY2016 (effective 10/1/2015): Added (first year of ICD-10-CM)
  • No changes since FY2016.

Common questions about O36.1990

Is O36.1990 billable?

Yes. O36.1990 is a billable/specific ICD-10-CM code valid for FY2027 (October 1, 2026 – September 30, 2027).

What does the "0" at the end of O36.1990 mean?

It is the 7th character for not applicable or unspecified.

Can O36.1990 be used as a principal diagnosis?

Yes. The Medicare Code Editor doesn't restrict O36.1990 as a principal diagnosis.

Is O36.1990 a CC or MCC?

No. O36.1990 is neither a CC nor an MCC under MS-DRG v44.0.

What DRG does O36.1990 group to?

O36.1990 is used in the MS-DRG v44.0 logic for MS-DRG 817 (Other Antepartum Diagnoses with O.R. Procedures with MCC), MS-DRG 818 (Other Antepartum Diagnoses with O.R. Procedures with CC), MS-DRG 819 (Other Antepartum Diagnoses with O.R. Procedures without CC/MCC), MS-DRG 831 (Other Antepartum Diagnoses without O.R. Procedures with MCC), MS-DRG 832 (Other Antepartum Diagnoses without O.R. Procedures with CC) and MS-DRG 833 (Other Antepartum Diagnoses without O.R. Procedures without CC/MCC). Which one applies depends on whether it is the principal diagnosis and on the rest of the claim.

What is the ICD-9 code for O36.1990?

The CMS General Equivalence Mappings map O36.1990 to ICD-9-CM 656.20.