2026 ICD-10-CM Diagnosis Code N11.1Chronic obstructive pyelonephritis
ICD-10-CM Codes›N00–N99›N10-N16›N11
- Billable — Valid for Submission
- CC — Complication or Comorbidity
- Chronic Condition
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. As a secondary diagnosis, it counts as a complication or comorbidity (CC) and moves an inpatient stay to a higher severity level within its MS-DRG family. It does not count, however, when the principal diagnosis is one of 70 closely related codes. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Urinary tract infections.
Code Identity
Code Classification
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
These terms are the conditions for which that code is to be used. The terms may be synonyms of the code title, or, in the case of "other specified" codes, the terms are a list of the various conditions assigned to that code. The inclusion terms are not necessarily exhaustive. Additional terms found only in the Alphabetic Index may also be assigned to a code.
A type 1 excludes note is a pure excludes note. It means "NOT CODED HERE!" An Excludes1 note indicates that the code excluded should never be used at the same time as the code above the Excludes1 note. An Excludes1 is used when two conditions cannot occur together, such as a congenital form versus an acquired form of the same condition.
Index to Diseases and InjuriesGuidance
Alphabetical index entries that point to this code.
Nephritis, nephritic (albuminuric) (azotemic) (congenital) (disseminated) (epithelial) (familial) (focal) (granulomatous) (hemorrhagic) (infantile) (nonsuppurative, excretory) (uremic) N05.9
Pyelonephritis See Also: Nephritis, tubulo-interstitial;
Stricture See Also: Stenosis;
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
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.
Code HistoryHistory
Questions About N11.1Overview
What is the ICD-10 code for chronic obstructive pyelonephritis?
The ICD-10-CM code for chronic obstructive pyelonephritis is N11.1 (sometimes written as N111). It is billable on HIPAA-covered claims from October 1, 2025 through September 30, 2026.
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.
Is N11.1 a CC or MCC?
CMS lists N11.1 as a CC (complication or comorbidity) for FY 2026. Reported as a secondary diagnosis, it moves the inpatient stay to a higher-weighted DRG within its severity family. It does not count when the principal diagnosis is one of the 70 closely related codes in its exclusion list.
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.
