2027 ICD-10-CM Diagnosis Code O36.8390Maternal care for abnormalities of the fetal heart rate or rhythm, unspecified trimester, not applicable or unspecified

ICD-10-CM Codes›O00-O9A›O30-O48›O36

ICD-10-CM O36.8390
CMSSource: CMS FY 2027 ICD-10-CM dataset · Effective Oct 1, 2026 – Sep 30, 2027

O36.8390 is a billable ICD-10-CM diagnosis code for maternal care for abnormalities of the fetal heart rate or rhythm, unspecified trimester, not applicable or unspecified. The 7th character 0 shows this applies to a single gestation, or that the affected fetus is not identified. 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
O36.8390
Billable Status
Yes — Valid for Submission
Code Describes
Maternal care for abnormalities of the fetal heart rate or rhythm, unspecified trimester, not applicable or unspecified
Short Description
Matern care for abnlt fetl hrt rate or rhym, unsp tri, unsp
Parent Code
O36.839
Maternal care for abnormalities of the fetal heart rate or rhythm, unspecified trimester

Code Classification

ChapterO00-O9APregnancy, childbirth and the puerperium
SectionO30-O48Maternal care related to the fetus and amniotic cavity and possible delivery problems
CategoryO36Maternal care for other fetal problems
This CodeO36.8390Maternal care for abnormalities of the fetal heart rate or rhythm, unspecified trimester, not applicable or unspecified

Code EditsBilling

Medicare Code Editor checks that affect claim validity for O36.8390.

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).

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Abnormal cardiac rate
  • Abnormal fetal heart rate
  • Abnormal fetal heart rhythm
  • Abnormal heart beat
  • Absent fetal heart rate variability
  • Baseline bradycardia
  • Baseline tachycardia
  • Bradycardia - baseline fetal heart rate
  • Early and late fetal heart decelerations
  • Early fetal heart deceleration
  • Fetal bradycardia
  • Fetal bradycardia affecting management of mother
  • Fetal distress affecting management of mother
  • Fetal dysrhythmia
  • Fetal heart acceleration
  • Fetal heart baseline pattern - finding
  • Fetal heart baseline rate range 160 to 180
  • Fetal heart baseline rate range 180 to 200
  • Fetal heart baseline rate range 40 to 80
  • Fetal heart baseline rate range 80 to 100
  • Fetal heart baseline rate range above 200
  • Fetal heart baseline rate range below 40
  • Fetal heart deceleration
  • Fetal heart rate absent
  • Fetal heart rate acceleration absent
  • Fetal heart rate not observed
  • Fetal heart rate variability - finding
  • Fetal heart rhythm - finding
  • Fetal heart sounds absent
  • Fetal heart sounds present
  • Fetal heart sounds quiet
  • Fetal tachycardia
  • Fetal tachycardia affecting management of mother
  • Finding of fetal heart sounds
  • Finding of regularity of heart rhythm
  • Irregular fetal heart rhythm
  • Irregular heart beat
  • Late fetal heart deceleration
  • Marked fetal heart rate variability
  • Minimal fetal heart rate variability
  • Moderate fetal heart rate variability
  • Poor baseline variability in fetal heart rate
  • Prolonged fetal heart deceleration
  • Prolonged fetal heart rate acceleration
  • Sinusoidal pattern of fetal heart
  • Tachycardia - baseline fetal heart rate
  • Variable fetal heart decelerations
  • Volume of fetal heart sounds - finding
  • Volume of heart sounds - finding

Instructional NotesGuidance

Instructions from the official ICD-10-CM Tabular List that apply to O36.8390: its own notes plus those printed at O36 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 O36 Maternal care for other fetal problems applies to 399 codes
  • the listed conditions in the fetus as a reason for hospitalization or other obstetric care of 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 O36 Maternal care for other fetal problems applies to 399 codes
  • encounter for suspected maternal and fetal conditions ruled out (Z03.7-)
  • placental transfusion syndromes (O43.0-)
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 O36 Maternal care for other fetal problems applies to 399 codes
  • labor and delivery complicated by fetal stress (O77.-)
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.

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 O36 Maternal care for other fetal problems applies to 399 codes
  • 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.
Values for category O36 Fetus Identification
  • 0not applicable or unspecified this code
  • 1fetus 1
  • 2fetus 2
  • 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 O36.8390, its category, or a range that includes it.

Excludes1 1

These codes carry an Excludes1 note naming O36.8390: 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 O36.-, 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

Convert O36.8390 to ICD-9-CMHistory

The closest ICD-9-CM equivalents under the General Equivalence Mappings.

ICD-9-CM
656.80 Fet/plac prob NEC-unspec
Approximate The match is approximate rather than exact.

Code History & ChangesHistory

Replacement O36.8390 replaces the following previously assigned code(s):

  • O36.8990 - Maternal care for oth fetal problems, unsp trimester, unsp
FY 2019AddedAdded to the ICD-10-CM code setEffective October 1, 2018.
FY 2020–2026No changes
FY 2027CurrentCurrent code set, no changesEffective October 1, 2026 through September 30, 2027.

Questions About O36.8390Overview

Is O36.8390 a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report maternal care for abnormalities of the fetal heart rate or rhythm, unspecified trimester, not applicable or unspecified on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

What does the 7th character 0 in O36.8390 mean?

The final character 0 shows the maternal care for abnormalities of the fetal heart rate or rhythm, unspecified trimester applies to a single gestation, or that the affected fetus cannot be identified.

What MS-DRG does O36.8390 group to?

When maternal care for abnormalities of the fetal heart rate or rhythm, unspecified trimester, not applicable or unspecified 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 O36.8390 be reported for?

The Medicare Code Editor checks maternal care for abnormalities of the fetal heart rate or rhythm, unspecified trimester, not applicable or unspecified against patient demographics: this code is intended for maternity cases (age 9 through 64). Claims outside these limits are flagged as inconsistent.

Can O36.8390 be reported with a code from Z03.7?

Not as a rule. The Excludes1 note at O36, which applies to O36.8390, 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).