2026 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 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

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 2026 (October 1, 2025 through September 30, 2026) 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 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

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 2018AddedAdded to the ICD-10-CM code setEffective October 1, 2017.
FY 2019–2025No changes
FY 2026CurrentCurrent code set, no changesEffective October 1, 2025 through September 30, 2026.

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, 2025 through September 30, 2026.

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 817, 818, 819, 831, 832, 833, with relative weights from 0.5229 to 1.6880 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.

What is the ICD-9 equivalent of O36.8390?

Under the General Equivalence Mappings, maternal care for abnormalities of the fetal heart rate or rhythm, unspecified trimester, not applicable or unspecified converts to ICD-9-CM 656.80 (fet/plac prob NEC-unspec). The mapping is approximate, so confirm the match fits the documentation.

Footnotes

[1] Not chronic - A diagnosis code that does not fit the criteria for chronic condition (duration, ongoing medical treatment, and limitations) is considered not chronic. Some codes designated as not chronic are acute conditions. Other diagnosis codes that indicate a possible chronic condition, but for which the duration of the illness is not specified in the code description (i.e., we do not know the condition has lasted 12 months or longer) also are considered not chronic.