2026 ICD-10-CM Diagnosis Code N99.512Cystostomy malfunction

ICD-10-CM Codes›N00–N99›N99›N99

ICD-10-CM N99.512
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

N99.512 is a billable ICD-10-CM diagnosis code for cystostomy malfunction. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 698 through 700. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Postprocedural or postoperative genitourinary system complication.

Code Identity

ICD-10-CM Code
N99.512
Billable Status
Yes — Valid for Submission
Code Describes
Cystostomy malfunction
Short Description
Cystostomy malfunction
Same as the full description in the CMS dataset.
Parent Code
N99.51
Complication of cystostomy

Code Classification

ChapterN00–N99Diseases of the genitourinary system
SectionN99Intraoperative and postprocedural complications and disorders of genitourinary system, not elsewhere classified
CategoryN99Intraoperative and postprocedural complications and disorders of genitourinary system, not elsewhere classified
This CodeN99.512Cystostomy malfunction

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Cystostomy malfunction

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.

    • Complication(s) (from) (of)
      • cystostomy (stoma)
        • malfunction
    • Malfunction
      • cystostomy (stoma)

Clinical ClassificationClinical

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

CCSR GEN026
Postprocedural or postoperative genitourinary system complication
Default principal diagnosis: inpatient Yes · outpatient Yes

Patient EducationClinical

Ostomy

An ostomy is surgery to create an opening (stoma) from an area inside the body to the outside. It treats certain diseases of the digestive or urinary systems. It can be permanent, when an organ must be removed. It can be temporary, when the organ needs time to heal. The organ could be the small intestine, colon, rectum, or bladder.

Read the full article at MedlinePlus

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

Convert N99.512 to ICD-9-CMHistory

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

ICD-9-CM
596.82 Mech comp of cystostomy
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 N99.512Overview

Is N99.512 (Complication of cystostomy) a billable code?

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

What MS-DRG does N99.512 group to?

When cystostomy malfunction is the principal diagnosis on an inpatient stay, it groups to MS-DRG 698, 699, 700, with relative weights from 0.6899 to 1.6544 depending on complications. Higher weights mean higher Medicare reimbursement.

What is the ICD-9 equivalent of N99.512?

Under the General Equivalence Mappings, cystostomy malfunction converts to ICD-9-CM 596.82 (mech comp of cystostomy). 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.