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N21.0 ICD-10-CM Code: Calculus in bladder

Compare with another code for N21.0Check this code on a claim

Billing Status: YES. This is a valid, specific, and billable ICD-10-CM reference.

Coding at a Glance

Official instructions
3 inclusion terms · 1 Excludes2

What these terms mean →

Billable · FY2027A valid, specific ICD-10-CM code, reportable for dates of service in FY2027.

What you need to know

Source: CMS/NCHS Official ICD-10-CM tabular notes, quoted. From the CMS/NCHS tabular list for the release in force. A note the category or block publishes applies to this code too, and is marked with where it comes from.

Excludes2Not included here; may be reported together
  • staghorn calculus (N20.0)
IncludesWhat this code covers
  • calculus of lower urinary tract with cystitis and urethritis (from N21)
  • Calculus in diverticulum of bladder
  • Urinary bladder stone

Where it sits Source: CMS/NCHS

Under:Chapter 14: Diseases of the Genitourinary SystemN20-N23 UrolithiasisN21 Calculus of lower urinary tract

Most relevant related codes MedCoder-derived

Read off the official notes above and this code’s own position in the tabular list. Which to report is a documentation question; Compare shows the two side by side.

CompareCheck ClaimView Related Codes

Inpatient Payment Groups (MS-DRG)

Potential MS-DRG participation — not a DRG assignment.

MS-DRGs this diagnosis helps define, as principal or secondary, per the CMS ICD-10-CM/PCS MS-DRG Definitions Manual v44, Appendix B.

A diagnosis appearing in a group's logic does not by itself determine the DRG assigned to a stay; the grouper uses the full claim.

Coding instructions

Official Tabular Instructional Notes: the inclusion, exclusion and sequencing notes published for N21.0 in the official ICD-10-CM tabular list, quoted as published.

Source: CMS/CDC — ICD-10-CM Tabular ListRelease: FY2027Effective: October 1, 2026

Trace:FY2027 changesChange historyRelease, file and checksum

Notes without a marker are published on N21.0 itself; “inherited from” names the category or block whose note applies here.

Includes

Conditions the official ICD-10-CM tabular list includes under this code.

  • calculus of lower urinary tract with cystitis and urethritis

Source: inherited from N21

Inclusion Terms

Alternative terms the tabular list files under this code.

  • Calculus in diverticulum of bladder
  • Urinary bladder stone

Excludes2 — Not Included Here

Conditions not covered by this code, but which may be reported alongside it when both are present.

Coder workflow for N21.0

MedCoder structured workflow — derived from this code’s own official record

Documentation check

The provider’s diagnostic statement
Codes are assigned from the provider’s documented diagnosis, not from clinical criteria, test values or a medication list (Guidelines I.A.19).

Official instructions as workflow

  • Excludes2 — not part of N21.0(1 note)

    Coding workflow: The conditions named in this note are not included in N21.0. When the record documents both, both may be reported; the note is a boundary, not a prohibition.

    CompareN20.0

    See the official tabular notes · Guidelines I.A.12.b

Every row is derived from this code’s own record — its title, tabular notes, 7th-character family and same-category siblings — with fixed MedCoder wording; nothing is inferred about a patient. The official notes and guideline text are in the sections each row links to, and they control.

Don’t confuse N21.0 with…

MedCoder analysis — pairs from this code’s official notes, distinctions written by MedCoder

The codes most likely to be picked instead of N21.0 — named in its own official notes, or sharing its laterality or encounter family — with what separates them and which documentation moves the case. Each links to the full comparison.

  • N21.9— Specificity relationship (Review)

    Overlapping diagnoses in the same category.

    Overlapping codes in the same category — the documentation decides which is the more specific fit.

    What moves you there: A record that documents no more than “Calculus of lower urinary tract, unspecified” takes N21.9; specificity in the record moves it back here.

    Full comparison: N21.0 vs N21.9 →

  • N20.0— Excludes2 relationship (Informational)

    Distinct conditions — both may be reported.

    A distinct condition — both may be reported when both are documented.

    What moves you there: Documentation of staghorn calculus adds N20.0; it is not part of this code and both may be reported when both are documented.

    Full comparison: N21.0 vs N20.0 →

Relationships are read from this code's own official notes, its laterality siblings and its encounter family; the wording of each distinction is MedCoder editorial, and the documentation named in each “what moves you there” line is the official note phrase or sibling title itself. Source: CMS ICD-10-CM tabular instructional notes; ICD-10-CM Official Guidelines, Section I.A.12.a.

Coding context

Guidelines, coding notes, decision aids, relationships (with MS-DRG and CCSR classification), hierarchy, HCC, coverage and the context map: what a coder reaches for after the core. Each section names whether it is official source data, a MedCoder-derived relationship or MedCoder editorial.

Code Overview

Calculus in bladder is a billable ICD-10-CM diagnosis code (N21.0).

MedCoder summary Summary composed by MedCoder from this code's official ICD-10-CM record. The tabular instructional notes themselves appear verbatim below.

Verify Before Coding

  • No Medicare Code Editor or MS-DRG Definitions Manual restrictions apply to this code.

From the code registry, the Medicare Code Editor, and the MS-DRG Definitions Manual. Check it against a full claim in Claim Check.

Relationships & Classification

MedCoder-derived relationships — computed from published CMS and AHRQ datasets

Other codes that name N21.0 or its code family, from the CMS ICD-10-CM tabular instructional notes. Tabular-note edges are stored at the code family level that carries each note.

Referenced by 7 Excludes2 notes: N25 — Disorders resulting from impaired renal tubular function (via N21.-), N25-N29 — Other disorders of kidney and ureter (N25-N29) (via N21.-), N26 — Unspecified contracted kidney (via N21.-), N27 — Small kidney of unknown cause (via N21.-), N28 — Other disorders of kidney and ureter, not elsewhere classified (via N21.-), N29 — Other disorders of kidney and ureter in diseases classified elsewhere (via N21.-), N32 — Other disorders of bladder.

These codes’ tabular lists name this diagnosis as distinct — both may be reported when both are documented.

MS-DRG Grouper Relationships (FY2027)

Potential MS-DRG participation — not a DRG assignment.

FY2027 MS-DRG: not on the CMS CC/MCC list — as a secondary diagnosis this code does not change MS-DRG severity for that release.

Named in the grouper logic of 2 MS-DRGs: DRG 693 (MDC 11), DRG 694 (MDC 11).

From the CMS MS-DRG Definitions Manual (Appendices B and C). Actual DRG assignment depends on the complete claim.

Clinical classification (AHRQ CCSR):GEN005 — Calculus of urinary tract (default).

Clinical Classifications Software Refined (CCSR) for ICD-10-CM Diagnoses. Healthcare Cost and Utilization Project (HCUP), Agency for Healthcare Research and Quality.

Related Codes

Same clinical category (CCSR)

AHRQ's Clinical Classifications Software groups these diagnoses under the same clinical category (Calculus of urinary tract).

N13.2 — Hydronephrosis with renal and ureteral calculous obstruction, N20.0 — Calculus of kidney, N20.1 — Calculus of ureter, N20.2 — Calculus of kidney with calculus of ureter, N20.9 — Urinary calculus, unspecified, N21.1 — Calculus in urethra, N21.8 — Other lower urinary tract calculus, N21.9 — Calculus of lower urinary tract, unspecified, N22 — Calculus of urinary tract in diseases classified elsewhere

Same Index main term, other category

The ICD-10-CM Index to Diseases and Injuries files this code under the main terms “Cystitis”, “Stone”, “Calculus, calculi, calculous”; these codes share that main term but sit in a different category of the Tabular List.

K80.71 — Calculus of gallbladder and bile duct without cholecystitis with obstruction (gallbladder and bile duct, with, obstruction), K80.80 — Other cholelithiasis without obstruction (hepatobiliary), K80.81 — Other cholelithiasis with obstruction (hepatobiliary, with obstruction), K86.89 — Other specified diseases of pancreas (pancreas), N13.2 — Hydronephrosis with renal and ureteral calculous obstruction (ureter, with hydronephrosis), N13.6 — Pyonephrosis (pyelitis, with hydronephrosis), N20.0 — Calculus of kidney (renal), N20.1 — Calculus of ureter (ureter), N20.2 — Calculus of kidney with calculus of ureter (ureter, with calculus, kidney), N20.9 — Urinary calculus, unspecified (urinary), N30.00 — Acute cystitis without hematuria (acute), N30.01 — Acute cystitis with hematuria (acute, with hematuria), N30.10 — Interstitial cystitis (chronic) without hematuria (chronic, interstitial), N30.11 — Interstitial cystitis (chronic) with hematuria (chronic, interstitial, with hematuria), N30.20 — Other chronic cystitis without hematuria (chronic), N30.21 — Other chronic cystitis with hematuria (chronic, with hematuria), N30.30 — Trigonitis without hematuria (of trigone), N30.31 — Trigonitis with hematuria (of trigone, with hematuria), N30.40 — Irradiation cystitis without hematuria (irradiation), N30.41 — Irradiation cystitis with hematuria (irradiation, with hematuria), +72 more

Contextual Map

Every relationship of N21.0 in one view: hierarchy, official tabular instructions in both directions, clinical classification, risk adjustment, MS-DRG participation, index terms and change history — each edge carrying the CMS source it derives from.

Run N21.0 with these 8 related codes in Claim Check

Hierarchy

Excludes2

Referenced by Excludes2 notes

Clinical classification (CCSR)

MS-DRG Grouper

MDC crossing

  • MDC 11 — Diseases and Disorders of the Kidney and Urinary Tract[MDC crossing]: “Diseases and Disorders of the Kidney and Urinary Tract — the grouper's crossing between diagnoses and procedures: a principal diagnosis sets the MDC, and same-MDC procedures move the stay to its surgical DRGs. 3,578 same-MDC procedures group here; browse them on the MDC page.”— CMS MS-DRG Definitions Manual · FY2027

Index entries

  • Calculus, calculi, calculous, bladder (encysted) (impacted) (urinary) (diverticulum)[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2027
  • Calculus, calculi, calculous, cystic[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2027
  • Calculus, calculi, calculous, diverticulum, bladder[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2027
  • Calculus, calculi, calculous, vesical (impacted)[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2027
  • Cystitis (exudative) (hemorrhagic) (septic) (suppurative), calculous[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2027
  • Cystolithiasis[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2027
  • Stone (s), bladder (diverticulum)[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2027
  • Stone (s), urinary (duct) (impacted) (passage), bladder (diverticulum)[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2027

Nearest codes

Change history

  • FY2016 — In the code set at ICD-10-CM adoption [Change history]— CMS release files (code change ledger) · icd10cm-fy2016

Reference

Index terms and tables, published questions and FAQ, every source behind this page with its release and checksum, the date-of-service check and the complete change history.

Indexed Clinical Terms (8)

Official source data — entries quoted as published, in the Index’s own lookup phrasing

Clinical term phrases from the official ICD-10-CM Index to Diseases and Injuries that map to this code. These are alphabetic-index entries shown as the Index writes them — lookup phrasing, not necessarily the wording of a final diagnosis.

Sources for this page

Codes, titles, notes, index terms and mappings on this page are transcribed from the datasets below. Relationships MedCoder computed and text MedCoder wrote are labelled where they appear.

Code, title, tabular notes and index terms Official source data
CMS/CDC ICD-10-CM FY2027 tabular list, index and tables, effective October 1, 2026 Release, file and checksum · Publisher’s page
Claim edits Official source data
CMS Definitions of Medicare Code Edits — v44.0 (October 2026) Release, file and checksum · Publisher’s page
Inpatient payment groups Official source data
CMS MS-DRG Definitions Manual (incl. Appendix B diagnosis index, Appendix C CC/MCC list, Appendix E procedure index) and IPPS Final Rule tables — v44 Release, file and checksum · Publisher’s page
Change history and date-of-service validity Official source data
CMS ICD-10-CM release addenda, ingested release by release into the change ledger Release, file and checksum · Publisher’s page
Comparisons, relationships and the contextual map MedCoder-derived relationship
Computed by MedCoder from the tabular notes and tables above; every derived relationship is marked as derived where it appears
Summary and FAQ answers MedCoder editorial explanation
Written by MedCoder to explain the sources above: drafted with AI assistance, checked by a person against the release files, and labelled as MedCoder text where it appears. Not official text.

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

Labels on this page: Official source data · MedCoder-derived relationship · MedCoder editorial explanation. How to read the labels · All data sources and release dates · CMS coding rules

Cite this page

Reference this page in a research guide, syllabus or article. The release is included because code content changes each year.

MedCoder.ai. "N21.0 — Calculus in bladder." ICD-10-CM FY2027. https://medcoder.ai/icd10/code/n21.0-calculus-in-bladder

Change history

  • FY2016 — October 1, 2015
    In the code set at ICD-10-CM adoption
    Calculus in bladder

No changes since FY2016 — additions, deletions, description changes and billable-status changes are tracked through FY2027, and none are recorded for this code. Note changes are tracked from FY2027 only.

Nearest Codes in This Family

Official ICD-10-CM classifications closest to N21.0 in its code family, with their registry titles.

View all codes in the N21 family