2026 ICD-10-CM Diagnosis Code N11.1Chronic obstructive pyelonephritis

ICD-10-CM Codes›N00–N99›N10-N16›N11

ICD-10-CM N11.1
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

N11.1 is a billable ICD-10-CM diagnosis code for chronic obstructive pyelonephritis. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 693 through 694. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Urinary tract infections.

Code Identity

ICD-10-CM Code
N11.1
Billable Status
Yes — Valid for Submission
Code Describes
Chronic obstructive pyelonephritis
Short Description
Chronic obstructive pyelonephritis
Same as the full description in the CMS dataset.
Parent Code
N11
Chronic tubulo-interstitial nephritis

Code Classification

ChapterN00–N99Diseases of the genitourinary system
SectionN10-N16Renal tubulo-interstitial diseases
CategoryN11Chronic tubulo-interstitial nephritis
This CodeN11.1Chronic obstructive pyelonephritis

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Chronic obstructive pyelonephritis
  • Chronic pyelonephritis
  • Chronic urinary tract infection
  • Obstructive pyelonephritis
  • Pyelonephritis associated with another disorder

Tabular List NotesGuidance

Coding notes and annotation back-references applicable to this code.

Inclusion Terms

  • Pyelonephritis (chronic) associated with anomaly of pelviureteric junction
  • Pyelonephritis (chronic) associated with anomaly of pyeloureteric junction
  • Pyelonephritis (chronic) associated with crossing of vessel
  • Pyelonephritis (chronic) associated with kinking of ureter
  • Pyelonephritis (chronic) associated with obstruction of ureter
  • Pyelonephritis (chronic) associated with stricture of pelviureteric junction
  • Pyelonephritis (chronic) associated with stricture of ureter

Type 1 Excludes

  • calculous pyelonephritis N20.9
  • obstructive uropathy N13

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.

    • Kink, kinking
      • ureter (pelvic junction)
        • with
          • pyelonephritis (chronic)
    • Nephritis, nephritic(albuminuric) (azotemic) (congenital) (disseminated) (epithelial) (familial) (focal) (granulomatous) (hemorrhagic) (infantile) (nonsuppurative, excretory) (uremic)
      • tubulo-interstitial (in)
        • chronic (infectious)
          • obstructive
    • Obstruction, obstructed, obstructive
      • pyelonephritis (chronic)
    • Obstruction, obstructed, obstructive
      • ureter (functional) (pelvic junction) NEC
        • with
          • pyelonephritis (chronic)
    • Pyelonephritis
      • chronic
        • associated with ureteral obstruction or stricture
    • Pyelonephritis
      • chronic
        • obstructive
    • Pyelonephritis
      • in (due to)
        • obstruction
    • Pyelonephrosis(obstructive)
    • Stricture
      • ureter (postoperative)
        • with
          • pyelonephritis (chronic)

Clinical ClassificationClinical

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

CCSR GEN004
Urinary tract infections
Default principal diagnosis: inpatient Yes · outpatient Yes

Clinical InformationClinical

  • Chronic Pyelonephritis

    persistent pyelonephritis.

Patient EducationClinical

Urinary Tract Infections

The urinary system is the body's drainage system for removing wastes and extra water. It includes two kidneys, two ureters, a bladder, and a urethra. Urinary tract infections (UTIs) are the second most common type of infection in the body.

Read the full article at MedlinePlus

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

Convert N11.1 to ICD-9-CMHistory

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

ICD-9-CM
593.3 Stricture of ureter
ApproximateCombination The match is approximate, and more than one code can be needed to describe the source diagnosis. Confirm with contextual judgment.
ICD-9-CM
593.4 Ureteric obstruction NEC
ApproximateCombination The match is approximate, and more than one code can be needed to describe the source diagnosis. Confirm with contextual judgment.
ICD-9-CM
590.01 Chr pyeloneph w med necr
ApproximateCombination The match is approximate, and more than one code can be needed to describe the source diagnosis. Confirm with contextual judgment.

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 N11.1Overview

Is N11.1 (Chronic tubulo-interstitial nephritis) a billable code?

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

What MS-DRG does N11.1 group to?

When chronic obstructive pyelonephritis is the principal diagnosis on an inpatient stay, it groups to MS-DRG 693, 694, with relative weights from 0.7817 to 1.3445 depending on complications. Higher weights mean higher Medicare reimbursement.

What is the ICD-9 equivalent of N11.1?

Under the General Equivalence Mappings, chronic obstructive pyelonephritis converts to ICD-9-CM 593.3 (stricture of ureter), 593.4 (ureteric obstruction NEC), and 590.01 (chr pyeloneph w med necr). The mapping is approximate, so confirm the match fits the documentation.

Footnotes

[1] Chronic - a chronic condition code indicates a condition lasting 12 months or longer and its effect on the patient based on one or both of the following criteria:

  • The condition results in the need for ongoing intervention with medical products,treatment, services, and special equipment
  • The condition places limitations on self-care, independent living, and social interactions.