2026 ICD-10-CM Diagnosis Code N13.1Hydronephrosis with ureteral stricture, not elsewhere classified
ICD-10-CM Codes›N00–N99›N10-N16›N13
- Billable — Valid for Submission
- CC — Complication or Comorbidity
- Not Chronic
N13.1 is a billable ICD-10-CM diagnosis code for hydronephrosis with ureteral stricture, not elsewhere classified. 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, 791, 793. 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 226 closely related codes. Coders also document this condition as acquired hydronephrosis. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Other specified and unspecified diseases of kidney and ureters.
Code Identity
Code Classification
Approximate SynonymsGuidance
Alternate terms and clinical phrases that map to this code.
- Acquired hydronephrosis
- Acquired hydronephrosis due to ureteral obstruction
- Acquired hydronephrosis due to ureteral orifice obstruction
- Hydronephrosis due to ureteral stricture
- Obstruction of ureteral orifice
- Stricture of ureter
Tabular List NotesGuidance
Coding notes and annotation back-references applicable to this code.
Type 1 Excludes
- Hydronephrosis with ureteral stricture with infection N13.6
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.
Hydronephrosis (atrophic) (early) (functionless) (intermittent) (primary) (secondary) NEC N13.30
ureteral NEC N13.1
ureteral stricture NEC N13.1
Stricture See Also: Stenosis;
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
Patient EducationClinical
Kidney Diseases
You have two kidneys, each about the size of your fist. They are near the middle of your back, just below the rib cage. Inside each kidney there are about a million tiny structures called nephrons. They filter your blood. They remove wastes and extra water, which become urine. The urine flows through tubes called ureters.
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Convert N13.1 to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About N13.1Overview
What is the ICD-10 code for hydronephrosis with ureteral stricture, not elsewhere classified?
The ICD-10-CM code for hydronephrosis with ureteral stricture, not elsewhere classified is N13.1 (sometimes written as N131). It is billable on HIPAA-covered claims from October 1, 2025 through September 30, 2026.
Is N13.1 (Obstructive and reflux uropathy) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report hydronephrosis with ureteral stricture, not elsewhere classified on HIPAA-covered claims from October 1, 2025 through September 30, 2026.
What MS-DRG does N13.1 group to?
When hydronephrosis with ureteral stricture, not elsewhere classified is the principal diagnosis on an inpatient stay, it groups to MS-DRG 693, 694, 791, 793, with relative weights from 0.7817 to 4.1696 depending on complications. Higher weights mean higher Medicare reimbursement.
Is N13.1 a CC or MCC?
CMS lists N13.1 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 226 closely related codes in its exclusion list.
What is the ICD-9 equivalent of N13.1?
Under the General Equivalence Mappings, hydronephrosis with ureteral stricture, not elsewhere classified converts to ICD-9-CM 591 (hydronephrosis) and 593.3 (stricture of ureter). The mapping is approximate, so confirm the match fits the documentation.
