2026 ICD-10-CM Diagnosis Code H95.133Mucosal cyst of postmastoidectomy cavity, bilateral ears

ICD-10-CM Codes›H60–H95›H95›H95

ICD-10-CM H95.133
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

H95.133 is a billable ICD-10-CM diagnosis code for mucosal cyst of postmastoidectomy cavity, bilateral ears. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 154 through 156. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Diseases of middle ear and mastoid (except otitis media) and Postprocedural or postoperative ear and/or mastoid process complication.

Code Identity

ICD-10-CM Code
H95.133
Billable Status
Yes — Valid for Submission
Code Describes
Mucosal cyst of postmastoidectomy cavity, bilateral ears
Short Description
Mucosal cyst of postmastoidectomy cavity, bilateral ears
Same as the full description in the CMS dataset.
Parent Code
H95.13
Mucosal cyst of postmastoidectomy cavity

Code Classification

ChapterH60–H95Diseases of the ear and mastoid process
SectionH95Intraoperative and postprocedural complications and disorders of ear and mastoid process, not elsewhere classified
CategoryH95Intraoperative and postprocedural complications and disorders of ear and mastoid process, not elsewhere classified
This CodeH95.133Mucosal cyst of postmastoidectomy cavity, bilateral ears

Clinical ClassificationClinical

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

CCSR EAR002
Diseases of middle ear and mastoid (except otitis media)
Default principal diagnosis: inpatient No · outpatient No
CCSR EAR005
Postprocedural or postoperative ear and/or mastoid process complication
Default principal diagnosis: inpatient Yes · outpatient Yes

Convert H95.133 to ICD-9-CMHistory

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

ICD-9-CM
383.31 Postmastoid mucosal cyst
Approximate The match is approximate rather than exact.

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 H95.133Overview

Is H95.133 (Mucosal cyst of postmastoidectomy cavity) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report mucosal cyst of postmastoidectomy cavity, bilateral ears on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What MS-DRG does H95.133 group to?

When mucosal cyst of postmastoidectomy cavity, bilateral ears is the principal diagnosis on an inpatient stay, it groups to MS-DRG 154, 155, 156, with relative weights from 0.6911 to 1.5635 depending on complications. Higher weights mean higher Medicare reimbursement.

What is the ICD-9 equivalent of H95.133?

Under the General Equivalence Mappings, mucosal cyst of postmastoidectomy cavity, bilateral ears converts to ICD-9-CM 383.31 (postmastoid mucosal cyst). 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.