2026 ICD-10-CM Diagnosis Code N13.30Unspecified hydronephrosis

ICD-10-CM Codes›N00–N99›N10-N16›N13

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

N13.30 is a billable ICD-10-CM diagnosis code for unspecified hydronephrosis. 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 Other specified and unspecified diseases of kidney and ureters.

Code Identity

ICD-10-CM Code
N13.30
Billable Status
Yes — Valid for Submission
Code Describes
Unspecified hydronephrosis
Short Description
Unspecified hydronephrosis
Same as the full description in the CMS dataset.
Parent Code
N13.3
Other and unspecified hydronephrosis

Code Classification

ChapterN00–N99Diseases of the genitourinary system
SectionN10-N16Renal tubulo-interstitial diseases
CategoryN13Obstructive and reflux uropathy
This CodeN13.30Unspecified hydronephrosis

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Acquired caliectasis
  • Acquired hydronephrosis
  • Acquired obstruction of urinary tract
  • Acquired obstructive defect of renal pelvis
  • Bilateral hydronephrosis
  • Dilatation of calyx
  • Dilatation of renal pelvis
  • Erythrocytosis due to hydronephrosis
  • Hydrocalycosis
  • Hydronephrosis
  • Idiopathic hydronephrosis
  • Inappropriate secondary erythrocytosis

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.

    • Hydronephrosis(atrophic) (early) (functionless) (intermittent) (primary) (secondary) NEC

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

Clinical InformationClinical

  • Hydronephrosis

    abnormal enlargement or swelling of a kidney due to dilation of the kidney calices and the kidney pelvis. it is often associated with obstruction of the ureter or chronic kidney diseases that prevents normal drainage of urine into the urinary bladder.

  • Pyonephrosis

    distention of kidney with the presence of pus and suppurative destruction of the renal parenchyma. it is often associated with renal obstruction and can lead to total or nearly total loss of renal function.

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.

Read the full article at MedlinePlus

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

Convert N13.30 to ICD-9-CMHistory

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

ICD-9-CM
591 Hydronephrosis
Approximate The match is approximate rather than exact.

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 N13.30Overview

Is N13.30 (Other and unspecified hydronephrosis) a billable code?

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

What MS-DRG does N13.30 group to?

When unspecified hydronephrosis 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 N13.30?

Under the General Equivalence Mappings, unspecified hydronephrosis converts to ICD-9-CM 591 (hydronephrosis). The mapping is approximate, so confirm the match fits the documentation.

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.