2027 ICD-10-CM Diagnosis Code O35.01X2Maternal care for (suspected) central nervous system malformation or damage in fetus, agenesis of the corpus callosum, fetus 2

ICD-10-CM Codes›O00-O9A›O30-O48›O35

ICD-10-CM O35.01X2
CMSSource: CMS FY 2027 ICD-10-CM dataset · Effective Oct 1, 2026 – Sep 30, 2027

O35.01X2 is a billable ICD-10-CM diagnosis code for maternal care for (suspected) central nervous system malformation or damage in fetus, agenesis of the corpus callosum, fetus 2. The 7th character 2 identifies fetus 2 in a multiple gestation pregnancy. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 817 through 819, 831 through 833. The code is restricted by the Medicare Code Editor to maternity cases (age 9 through 64). In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Maternal care related to fetal conditions.

Code Identity

ICD-10-CM Code
O35.01X2
Billable Status
Yes — Valid for Submission
Code Describes
Maternal care for (suspected) central nervous system malformation or damage in fetus, agenesis of the corpus callosum, fetus 2
Short Description
Mat care cnsl malf/damag fts, agenesis corpus callosum, fts2
Parent Code
O35.01
Maternal care for (suspected) central nervous system malformation or damage in fetus, agenesis of the corpus callosum

Code Classification

ChapterO00-O9APregnancy, childbirth and the puerperium
SectionO30-O48Maternal care related to the fetus and amniotic cavity and possible delivery problems
CategoryO35Maternal care for known or suspected fetal abnormality and damage
This CodeO35.01X2Maternal care for (suspected) central nervous system malformation or damage in fetus, agenesis of the corpus callosum, fetus 2

Code EditsBilling

Medicare Code Editor checks that affect claim validity for O35.01X2.

Maternity diagnoses
The Medicare Code Editor detects inconsistencies in maternity cases by checking a patient's age and any diagnosis on the patient's record. The maternity code edits apply to patients age ange is 9–64 years inclusive (e.g., diabetes in pregnancy, antepartum pulmonary complication).

Instructional NotesGuidance

Instructions from the official ICD-10-CM Tabular List that apply to O35.01X2: its own notes plus those printed at O35.0, O35, and Chapter 15. A note printed at a category, block or chapter applies to every code under it.

Includes

Further defines, or gives examples of, the content of the category.

From O35 Maternal care for known or suspected fetal abnormality and damage applies to 231 codes
  • the listed conditions in the fetus as a reason for hospitalization or other obstetric care to the mother, or for termination of pregnancy

Excludes1

Not coded here: the excluded code is never reported together with this one, unless the two conditions are unrelated.

From O35 Maternal care for known or suspected fetal abnormality and damage applies to 231 codes
  • encounter for suspected maternal and fetal conditions ruled out (Z03.7-)
From Chapter 15 (O00-O9A) Pregnancy, childbirth and the puerperium applies to 2,481 codes
  • supervision of normal pregnancy (Z34.-)

Excludes2

Not included here: the excluded condition is not part of this code, but a patient may have both, so both codes may be reported.

From O35.0 Maternal care for (suspected) central nervous system malformation in fetus applies to 70 codes
  • chromosomal abnormality in fetus (O35.1-)
From Chapter 15 (O00-O9A) Pregnancy, childbirth and the puerperium applies to 2,481 codes
  • mental and behavioral disorders associated with the puerperium (F53.-)
  • obstetrical tetanus (A34)
  • postpartum necrosis of pituitary gland (E23.0)
  • puerperal osteomalacia (M83.0)

Use Additional Code

Add a second code, after this one, to fully describe the condition.

From Chapter 15 (O00-O9A) Pregnancy, childbirth and the puerperium applies to 2,481 codes
  • code, if applicable, from category Z3A, Weeks of gestation, to identify the specific week of the pregnancy, if known.

Code Also

A second code may be needed to fully describe the condition; the note gives no sequencing direction.

From O35 Maternal care for known or suspected fetal abnormality and damage applies to 231 codes
  • any associated maternal condition

Notes

General instructions on how these codes are used.

From Chapter 15 (O00-O9A) Pregnancy, childbirth and the puerperium applies to 2,481 codes
  • CODES FROM THIS CHAPTER ARE FOR USE ONLY ON MATERNAL RECORDS, NEVER ON NEWBORN RECORDS
  • Codes from this chapter are for use for conditions related to or aggravated by the pregnancy, childbirth, or by the puerperium (maternal causes or obstetric causes)
  • Trimesters are counted from the first day of the last menstrual period. They are defined as follows:
  • 1st trimester- less than 14 weeks 0 days
  • 2nd trimester- 14 weeks 0 days to less than 28 weeks 0 days
  • 3rd trimester- 28 weeks 0 days until delivery

7th Character

Every code in the category takes a 7th character from the listed values, with the placeholder X filling any empty positions before it.

From O35 Maternal care for known or suspected fetal abnormality and damage applies to 231 codes
  • One of the following 7th characters is to be assigned to each code under category O35. 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 O35 that has a 7th character of 1 through 9.
Values for category O35 Fetus Identification
  • 0not applicable or unspecified
  • 1fetus 1
  • 2fetus 2 this code
  • 3fetus 3
  • 4fetus 4
  • 5fetus 5
  • 9other fetus

Source: CMS ICD-10-CM Tabular List. How to read instructional notes.

Referenced in Other NotesGuidance

Instructional notes printed at other codes that name O35.01X2, its category, or a range that includes it.

Excludes1 1

These codes carry an Excludes1 note naming O35.01X2: they are not reported together with it, unless the two conditions are unrelated.

  • Z03.7 Encounter for suspected maternal and fetal conditions ruled out
    known or suspected fetal anomalies affecting management of mother, not ruled out (O26.-, O35.-, O36.-, O40.-, O41.-) names O35.-, which includes this code

Clinical ClassificationClinical

AHRQ’s CCSR groups this code into broader clinical categories.

CCSR PRG013
Maternal care related to fetal conditions
Default principal diagnosis: inpatient Yes · outpatient Yes

Patient EducationClinical

Brain Malformations

Most brain malformations begin long before a baby is born. Something damages the developing nervous system or causes it to develop abnormally. Sometimes it's a genetic problem. In other cases, exposure to certain medicines, infections, or radiation during pregnancy interferes with brain development.

Read the full article at MedlinePlus

Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.

Code History & ChangesHistory

Replacement O35.01X2 replaces the following previously assigned code(s):

  • O35.0XX2 - Maternal care for (suspected) cnsl malform in fetus, fetus 2
FY 2023AddedAdded to the ICD-10-CM code setEffective October 1, 2022.
FY 2024–2026No changes
FY 2027CurrentCurrent code set, no changesEffective October 1, 2026 through September 30, 2027.

Questions About O35.01X2Overview

Is O35.01X2 a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report maternal care for (suspected) central nervous system malformation or damage in fetus, agenesis of the corpus callosum, fetus 2 on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

What does the 7th character 2 in O35.01X2 mean?

The final character 2 identifies the fetus in a multiple gestation pregnancy: this code reports maternal care for (suspected) central nervous system malformation or damage in fetus, agenesis of the corpus callosum for fetus 2.

What MS-DRG does O35.01X2 group to?

When maternal care for (suspected) central nervous system malformation or damage in fetus, agenesis of the corpus callosum, fetus 2 is the principal diagnosis on an inpatient stay, it groups to MS-DRG 833, 832, 831, 819, 818, 817, with relative weights from 0.5000 to 1.7586 depending on complications. Higher weights mean higher Medicare reimbursement.

Who can O35.01X2 be reported for?

The Medicare Code Editor checks maternal care for (suspected) central nervous system malformation or damage in fetus, agenesis of the corpus callosum, fetus 2 against patient demographics: this code is intended for maternity cases (age 9 through 64). Claims outside these limits are flagged as inconsistent.

Can O35.01X2 be reported with a code from Z03.7?

Not as a rule. The Excludes1 note at O35, which applies to O35.01X2, lists "encounter for suspected maternal and fetal conditions ruled out (Z03.7-)". An Excludes1 note means the excluded code is never reported together with this one; the only exception is when the two conditions are unrelated to each other (Official Guidelines, Section I.A.12.a).