2026 ICD-10-CM Diagnosis Code R90.81Abnormal echoencephalogram

ICD-10-CM Codes›R00–R99›R90-R94›R90

ICD-10-CM R90.81
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

R90.81 is a billable ICD-10-CM diagnosis code for abnormal echoencephalogram. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026). As a symptom code, it should not be used as a principal diagnosis once a related definitive diagnosis has been established. Coders also document this condition as echoencephalogram abnormal. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Abnormal findings without diagnosis.

Code Identity

ICD-10-CM Code
R90.81
Billable Status
Yes — Valid for Submission
Code Describes
Abnormal echoencephalogram
Short Description
Abnormal echoencephalogram
Same as the full description in the CMS dataset.
Parent Code
R90.8
Other abnormal findings on diagnostic imaging of central nervous system

Code Classification

ChapterR00–R99Symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified
SectionR90-R94Abnormal findings on diagnostic imaging and in function studies, without diagnosis
CategoryR90Abnormal findings on diagnostic imaging of central nervous system
This CodeR90.81Abnormal echoencephalogram

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Echoencephalogram abnormal
  • Ultrasonography of brain abnormal

Index to Diseases and InjuriesGuidance

Alphabetical index entries that point to this code.

External Cause of Injuries IndexGuidance

References for this code in the External Cause of Injuries Index.

    • Abnormal, abnormality, abnormalities
      • echoencephalogram

Clinical ClassificationClinical

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

CCSR SYM017
Abnormal findings without diagnosis
Default principal diagnosis: inpatient Yes · outpatient Yes

Convert R90.81 to ICD-9-CMHistory

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

ICD-9-CM
794.01 Abnorm echoencephalogram
Exact Match The mapping is direct, with no qualifiers.

Code HistoryHistory

FY 2016AddedAdded to the ICD-10-CM code setEffective October 1, 2015, the first year of ICD-10-CM.
FY 2017–2025No changes
FY 2026CurrentCurrent code set, no changesEffective October 1, 2025 through September 30, 2026.

Questions About R90.81Overview

Is R90.81 a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report abnormal echoencephalogram on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

Can R90.81 be a principal diagnosis?

Use it with care. This is a symptom code, so once a definitive diagnosis explaining the abnormal echoencephalogram is established, that condition takes the principal position instead.

What is the ICD-9 equivalent of R90.81?

Under the General Equivalence Mappings, abnormal echoencephalogram converts to ICD-9-CM 794.01 (abnorm echoencephalogram). The mapping is a direct match.

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.