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N13.3 vs N20

N13.3 (Other and unspecified hydronephrosis) compared with N20 (Calculus of kidney and ureter), from the official CMS tabular data.

Current data releases:ICD-10-CM FY2027 · ICD-10-PCS FY2027 · HCPCS October 2026 · MS-DRG v44 · Medicare Code Editor v44.0 · NCCI PTP Q4 2026 · MUE Q4 2026 · NCD code lists 2026-01 · LCD export September 28, 2026 · All releases and sources

Summary

These codes can be reported together when both conditions are documented, because N13.3 lists N20 under Excludes2, which marks them as distinct conditions.

Official rule
What is different?

The conditions named.N13.3 is “Other and unspecified hydronephrosis”; N20 is “Calculus of kidney and ureter”.

Registry fact

Can these codes be reported together?

Yes, when both are documented.N13.3 lists N20 under Excludes2: “calculus of kidney and ureter without hydronephrosis (N20.-)”. Excludes2 marks distinct conditions that may both be reported when both are documented.

Official ruleGuide: Excludes1 vs Excludes2

Is there an Excludes1 relationship?

None.Neither entry carries an Excludes1 note that names the other code. N13.3 carries 2 Excludes1 notes and N20 carries 2 Excludes1 notes covering other codes; the side-by-side table quotes them.

Official rule

Is there an Excludes2 relationship?

Yes.N13.3’s tabular entry: “calculus of kidney and ureter without hydronephrosis (N20.-)”. The note covers N20.

Official ruleGuide: Excludes1 vs Excludes2

Is one more specific?

Not comparable.The codes sit in different categories; specificity is only comparable within one category.

Is one a parent or header code?

Both are headers.Both are non-billable headers, and neither contains the other.

Registry fact

Are there sequencing instructions?

None.Neither entry carries a Code First or Use Additional Code note that names the other.

Official rule

Are there other coding relationships?

None found.No laterality, encounter-phase, Table of Neoplasms, Table of Drugs and Chemicals, or history-versus-active-disease relationship links these codes.

MedCoder-derived

Official rule: a tabular instructional note or a section of the ICD-10-CM Official Guidelines, quoted as published. Registry fact: the codes’ own published attributes (titles, billable status, position in the hierarchy, code set). MedCoder-derived: a reading MedCoder computes from those facts; it is not itself a rule. How to read the labels

Can these codes be reported together?

Informational

Excludes2 relationship

N13.3
Other and unspecified hydronephrosis
↔
N20
Calculus of kidney and ureter

What we found

Yes, when both are documented.N13.3 carries an Excludes2 note covering N20: “calculus of kidney and ureter without hydronephrosis (N20.-)”

Excludes2 marks distinct conditions — both may be reported when both are documented.

What to review

Report both only when the documentation supports both conditions; otherwise report the one documented.

Guide: Excludes1 vs Excludes2Check these on a claim

Why it matters

An Excludes2 note means the excluded condition is not part of the code above it, but a patient can have both. Report both when both are documented.

Source / rule

CMS ICD-10-CM tabular instructional notes

Official guidance behind these answers

  • Section I.A.12.b — Excludes2 · applies to: Excludes2

    A type 2 Excludes note represents “Not included here.” An excludes2 note indicates that the condition excluded is not part of the condition represented by the code, but a patient may have both conditions at the same time. When an Excludes2 note appears under a code, it is acceptable to use both the code and the excluded code together, when appropriate.

    ICD-10-CM Official Guidelines FY2027

Quoted from the ICD-10-CM Official Guidelines for Coding and Reporting in effect for the release shown. The tabular notes above are the code-level instruction; these sections are the convention that says how such a note is applied. Source document (CMS PDF) · Release and checksum

Side by side

Similar descriptions do not make codes interchangeable. The documentation and the official instructions decide which code applies.

Official descriptionDiffers
N13.3

Other and unspecified hydronephrosis

N20

Calculus of kidney and ureter

StatusDiffers
N13.3
Non-billable header

A header is not reported on a claim; a code beneath it is.

Report instead: N13.30, N13.39

N20
Non-billable header

A header is not reported on a claim; a code beneath it is.

Report instead: N20.0, N20.1, N20.2, N20.9

Excludes1Differs
N13.3
  • hydronephrosis with infection (N13.6)
  • pyeloureteritis cystica (N28.85)
N20
  • nephrocalcinosis (E83.59)
  • that with hydronephrosis (N13.2)
Excludes2Differs
N13.3
  • calculus of kidney and ureter without hydronephrosis (N20.-)
  • congenital obstructive defects of renal pelvis and ureter (Q62.0-Q62.3)
  • hydronephrosis with ureteropelvic junction obstruction (Q62.11)
  • obstructive pyelonephritis (N11.1)
N20

None at this code

CategoryDiffers
N13.3

N13 Obstructive and reflux uropathy

N20

Is itself a category

ChapterSame for both

N00-N99 — Diseases of the Genitourinary System (N00-N99)

IncludesDiffers
N13.3
  • pyelonephritis
N20
  • Calculous pyelonephritis

No Code first, Use additional code, Code also and 7th character note at either code.

Notes are the code’s own tabular entry, quoted as published. A note that names the other code is the one the verdict above rests on. In a row that differs, notes every code shares are dimmed.

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Derived from the official CMS ICD-10-CM tabular data (FY2027). A coding-rule comparison, not billing advice: payer-specific edits and medical-necessity policy are outside its scope. All data sources