2026 ICD-10-CM Diagnosis Code N13.4Hydroureter

ICD-10-CM Codes›N00–N99›N10-N16›N13

ICD-10-CM N13.4
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

N13.4 is a billable ICD-10-CM diagnosis code for hydroureter. 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 68 closely related codes. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Other specified and unspecified diseases of kidney and ureters.

Code Identity

ICD-10-CM Code
N13.4
Billable Status
Yes — Valid for Submission
Code Describes
Hydroureter
Short Description
Hydroureter
Same as the full description in the CMS dataset.
Parent Code
N13
Obstructive and reflux uropathy

Code Classification

ChapterN00–N99Diseases of the genitourinary system
SectionN10-N16Renal tubulo-interstitial diseases
CategoryN13Obstructive and reflux uropathy
This CodeN13.4Hydroureter

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Hydroureter
  • Hydroureter due to necrotic papilla in ureter
  • Non-obstructive hydroureter
  • Obstructive hydroureter

Tabular List NotesGuidance

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

Type 1 Excludes

  • congenital hydroureter Q62.3
  • hydroureter with infection N13.6
  • vesicoureteral-reflux with hydroureter N13.73

Index to Diseases and InjuriesGuidance

Alphabetical index entries that point to this code.

Clinical ClassificationClinical

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

CCSR GEN006
Other specified and unspecified diseases of kidney and ureters
Default principal diagnosis: inpatient Yes · outpatient Yes

Patient EducationClinical

Ureteral Disorders

Your kidneys make urine by filtering wastes and extra water from your blood. The urine travels from the kidneys to the bladder in two thin tubes called ureters.

Read the full article at MedlinePlus

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

Convert N13.4 to ICD-9-CMHistory

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

ICD-9-CM
593.5 Hydroureter
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 N13.4Overview

What is the ICD-10 code for hydroureter?

The ICD-10-CM code for hydroureter is N13.4 (sometimes written as N134). It is billable on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

Is N13.4 (Obstructive and reflux uropathy) a billable code?

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

What MS-DRG does N13.4 group to?

When hydroureter 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 N13.4 a CC or MCC?

CMS lists N13.4 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 68 closely related codes in its exclusion list.

What is the ICD-9 equivalent of N13.4?

Under the General Equivalence Mappings, hydroureter converts to ICD-9-CM 593.5 (hydroureter). The mapping is a direct match.