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N13.6 ICD-10-CM Code: Pyonephrosis

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

Coding at a Glance

Tabular directives
3 inclusion terms · 1 Excludes1 · 4 Excludes2 · 1 use-additional code

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 v43, Appendix B.

  • MS-DRG 689 — KIDNEY AND URINARY TRACT INFECTIONS WITH MCC (MDC 11)
  • MS-DRG 690 — KIDNEY AND URINARY TRACT INFECTIONS WITHOUT MCC (MDC 11)
  • MS-DRG 791 — PREMATURITY WITH MAJOR PROBLEMS (MDC 15)
  • MS-DRG 793 — FULL TERM NEONATE WITH MAJOR PROBLEMS (MDC 15)

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 N13.6 in the official ICD-10-CM tabular list, quoted as published.

Source: CMS/CDC — ICD-10-CM Tabular ListRelease: FY2026Effective: October 1, 2025

Notes without a marker are published on N13.6 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.

  • pyelonephritis

Source: inherited from N10-N16

Inclusion Terms

Alternative terms the tabular list files under this code.

Excludes1 — Not Coded Here

Conditions generally not reported together with this code (Excludes1) -- an error unless the two conditions are documented as unrelated to each other (ICD-10-CM Official Guidelines, Section I.A.12.a).

Source: inherited from N10-N16

Excludes2 — Not Included Here

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

Source: inherited from N13

Use Additional Code

Supplementary codes the tabular list directs you to add.

  • Use additional code (B95-B97), to identify infectious agent.

Coder workflow for N13.6

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

Before you code N13.6

  1. Check the Excludes1 note: if the documentation supports a condition named there, do not simply proceed with N13.6. Excludes1 conditions are not reported together with this code unless the record shows they are unrelated (Guidelines I.A.12.a).

    See the official tabular notes

Choose the right path

  1. Does the documentation support a condition named in N13.6’s Excludes1 note?
    Yes → Do not simply proceed: review the excluded code. Both are reported only when the record shows the two conditions are unrelated.
    No → Continue.

    ReviewN28.85

Consider N13.6. Then work the Use Additional Code note, and confirm the code is valid for the date of service in the Verify section.

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).
The associated condition or complication
Whether the associated condition the title names is documented; the “with” convention presumes some links, and a provider statement that the conditions are unrelated defeats it (Guidelines I.A.15).
The conditions the Use Additional Code note names
Reported with this code when documented; a conditional instruction (“if applicable”, “if known”) applies only when the record supports it.

Official instructions as workflow

  • Excludes1 — check before selecting N13.6(1 note)

    Coding workflow: If the documentation supports a condition named in this note, do not simply proceed with N13.6: the two are not reported together. The one exception is when the record shows the two conditions are unrelated to each other.

    CompareN28.85

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

  • Excludes2 — not part of N13.6(4 notes)

    Coding workflow: The conditions named in this note are not included in N13.6. When the record documents both, both may be reported; the note is a boundary, not a prohibition.

    CompareN20, Q62.11, N11.1

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

  • Use Additional Code — after identifying N13.6(1 note)

    Coding workflow: Check whether the documentation supports the additional code(s) the note names, and report them with N13.6 when it does. Where the instruction is conditional (“if applicable”, “if known”), it applies only when the record documents the condition.

    See the official tabular notes · Guidelines I.A.13

Coding decision scenarios

Pattern scenarios for this code’s structure — decision rules, not clinical cases

Documentation: Both the condition N13.6 describes and a condition named in its Excludes1 note are documented for the same encounter.

Coding question: Can both codes be reported?

Path: Review the Excludes1 note and the excluded code, and look for a provider statement on whether the two conditions are related.

Reason: Excludes1 means the two are not coded together; the exception is when the record shows the conditions are unrelated to each other (Guidelines I.A.12.a).

ReviewN28.85

Documentation: A condition the Use Additional Code note names is documented.

Coding question: Is a second code reported with N13.6?

Path: Review the Use Additional Code note and the code it names.

Reason: The additional code is reported when the record documents the condition; a conditional instruction applies only when its condition is met (Guidelines I.A.13).

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.

Code Overview

Pyonephrosis is a billable ICD-10-CM diagnosis code (N13.6).

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

Indexed Clinical Terms (37)

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.

Decision Points

The directives on this code's own record, as a pre-claim checklist.

  1. 1 Use Additional Code instruction — report the named additional code(s) when the documentation supports them. See the Use Additional Code notes
  2. 1 Excludes1 entry — codes named there are generally not reported together with this code (Guidelines I.A.12.a). See the Excludes1 notes
  3. 4 Excludes2 entries — those conditions are not part of this code and may be reported additionally when documented. See the Excludes2 notes

Checklist rows are derived from this code's own official directives; the wording of each check is MedCoder editorial. The official notes themselves are in the sections each row links to.

Verify Before Coding

  • CC as a secondary diagnosis (FY2026). Can raise the stay's MS-DRG severity tier.

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 structured relationships — computed from published CMS and AHRQ datasets

Other codes that name N13.6 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 8 Excludes1 notes across 2 chapters: M72.8 — Other fibroblastic disorders, N11.1 — Chronic obstructive pyelonephritis (via N13.-), N13.1 — Hydronephrosis with ureteral stricture, not elsewhere classified, N13.2 — Hydronephrosis with renal and ureteral calculous obstruction, N13.3 — Other and unspecified hydronephrosis, N13.4 — Hydroureter, N13.5 — Crossing vessel and stricture of ureter without hydronephrosis, N39.0 — Urinary tract infection, site not specified.

These codes’ tabular lists mark this diagnosis as mutually exclusive — not reported together unless the conditions are documented as unrelated.

Referenced by 3 Code Also instructions: N80.A4 — Superficial endometriosis of ureter (via N13.-), N80.A5 — Deep endometriosis of ureter (via N13.-), N80.A6 — Endometriosis of ureter, unspecified depth (via N13.-).

These codes suggest coding this condition alongside when both are present.

MS-DRG Grouper Relationships (FY2026)

Potential MS-DRG participation — not a DRG assignment.

FY2026 MS-DRG: CC — Complication or Comorbidity. Reported as a secondary diagnosis, this code raises the stay's MS-DRG severity tier — except when the principal diagnosis is one of 226 clinically related codes on its CMS exclusion list.

Named in the grouper logic of 4 MS-DRGs: DRG 689 (MDC 11), DRG 690 (MDC 11), DRG 791 (MDC 15), DRG 793 (MDC 15).

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

Clinical classification (AHRQ CCSR):GEN004 — Urinary tract infections (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 process (MS-DRG)

Acts as CC — raises the severity of other admissions. CMS groups these diagnoses into one MS-DRG principal-diagnosis exclusion process — a CC/MCC on this list never raises severity when the principal diagnosis is also on it.

N10 — Acute pyelonephritis, N11.0 — Nonobstructive reflux-associated chronic pyelonephritis, N11.8 — Other chronic tubulo-interstitial nephritis, N11.9 — Chronic tubulo-interstitial nephritis, unspecified, N12 — Tubulo-interstitial nephritis, not specified as acute or chronic, N13.0 — Hydronephrosis with ureteropelvic junction obstruction, N13.1 — Hydronephrosis with ureteral stricture, not elsewhere classified, N13.2 — Hydronephrosis with renal and ureteral calculous obstruction, N13.30 — Unspecified hydronephrosis, N13.39 — Other hydronephrosis, N14.0 — Analgesic nephropathy, N14.11 — Contrast-induced nephropathy, N14.19 — Nephropathy induced by other drugs, medicaments and biological substances, N14.2 — Nephropathy induced by unspecified drug, medicament or biological substance, N14.3 — Nephropathy induced by heavy metals, N14.4 — Toxic nephropathy, not elsewhere classified, N15.0 — Balkan nephropathy, N15.1 — Renal and perinephric abscess, N15.8 — Other specified renal tubulo-interstitial diseases, N15.9 — Renal tubulo-interstitial disease, unspecified, +205 more

Same clinical category (CCSR)

AHRQ's Clinical Classifications Software groups these diagnoses under the same clinical category (Urinary tract infections).

A56.01 — Chlamydial cystitis and urethritis, A59.03 — Trichomonal cystitis and urethritis, B37.41 — Candidal cystitis and urethritis, B37.49 — Other urogenital candidiasis, N10 — Acute pyelonephritis, N11.0 — Nonobstructive reflux-associated chronic pyelonephritis, N11.1 — Chronic obstructive pyelonephritis, N11.8 — Other chronic tubulo-interstitial nephritis, N11.9 — Chronic tubulo-interstitial nephritis, unspecified, N12 — Tubulo-interstitial nephritis, not specified as acute or chronic, N15.1 — Renal and perinephric abscess, N30.00 — Acute cystitis without hematuria, N30.01 — Acute cystitis with hematuria, N30.10 — Interstitial cystitis (chronic) without hematuria, N30.11 — Interstitial cystitis (chronic) with hematuria, N30.20 — Other chronic cystitis without hematuria, N30.21 — Other chronic cystitis with hematuria, N30.30 — Trigonitis without hematuria, N30.31 — Trigonitis with hematuria, N30.40 — Irradiation cystitis without hematuria, +40 more

Same Index main term, other category

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

M72.9 — Fibroblastic disorder, unspecified, M79.4 — Hypertrophy of (infrapatellar) fat pad (popliteal fat pad), M86.8X — Other osteomyelitis (Brodie's), M95.5 — Acquired deformity of pelvis (pelvis), N10 — Acute pyelonephritis (acute), N11.0 — Nonobstructive reflux-associated chronic pyelonephritis (nonobstructive, with reflux), N11.1 — Chronic obstructive pyelonephritis (in, obstruction), N11.8 — Other chronic tubulo-interstitial nephritis (chronic, specified NEC), N11.9 — Chronic tubulo-interstitial nephritis, unspecified (chronic), N12 — Tubulo-interstitial nephritis, not specified as acute or chronic (nonobstructive), N15.1 — Renal and perinephric abscess (kidney), N20.0 — Calculus of kidney (kidney, with calculus), N20.1 — Calculus of ureter (ureter), N20.2 — Calculus of kidney with calculus of ureter (ureter, with calculus, kidney), N20.9 — Urinary calculus, unspecified (anuria), N21.0 — Calculus in bladder (cystic), N21.1 — Calculus in urethra (urethra), N21.8 — Other lower urinary tract calculus (suburethral), N21.9 — Calculus of lower urinary tract, unspecified (urinary, lower), N26.2 — Page kidney (kidney, Page), +666 more

Lab tests where this diagnosis supports Medicare coverage (NCD)

Medicare's National Coverage Determination (NCD) program lists this diagnosis as medical justification for these lab tests.

Blood Glucose Test, Gamma-glutamyl Transferase (GGT) Test

Contextual Map

Every relationship of N13.6 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 N13.6 with these 14 related codes in Claim Check

Hierarchy

Use Additional Code

Referenced by Excludes1 notes

Referenced by Code Also instructions

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. 3,574 same-MDC procedures group here; browse them on the MDC page.”— CMS MS-DRG Definitions Manual · FY2026
  • MDC 15 — Newborns and Other Neonates with Conditions Originating in Perinatal Period[MDC crossing]: “Newborns and Other Neonates with Conditions Originating in Perinatal Period — 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.”— CMS MS-DRG Definitions Manual · FY2026

Index entries (37)

  • Abscess (connective tissue) (embolic) (fistulous) (infective) (metastatic) (multiple) (pernicious) (pyogenic) (septic), kidney, with calculus, with hydronephrosis[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
  • Angulation, ureter, with infection[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
  • Calculus, calculi, calculous, kidney (impacted) (multiple) (pelvis) (recurrent) (staghorn), congenital, with hydronephrosis, with infection[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
  • Calculus, calculi, calculous, kidney (impacted) (multiple) (pelvis) (recurrent) (staghorn), with calculus, ureter, with hydronephrosis, with infection[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
  • Calculus, calculi, calculous, pyelitis (impacted) (recurrent), with hydronephrosis[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
  • Calculus, calculi, calculous, pyelonephritis (impacted) (recurrent), with hydronephrosis[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
  • Calculus, calculi, calculous, ureter (impacted) (recurrent), with calculus, kidney, with hydronephrosis, with infection[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
  • Calculus, calculi, calculous, ureter (impacted) (recurrent), with hydronephrosis, with infection[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
  • and 29 more

Nearest codes (22)

Change history

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

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 FY2026 tabular list, index and tables, effective October 1, 2025 Release, file and checksum · Publisher’s page
Claim edits Official source data
CMS Definitions of Medicare Code Edits — v43.1 (April 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 — v43 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 structured 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 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.

Labels on this page: Official source data · MedCoder structured relationship · MedCoder explanation. How to read the labels · All data sources and release dates

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. "N13.6 — Pyonephrosis." ICD-10-CM FY2026. https://medcoder.ai/icd10/code/n13.6-pyonephrosis

Change history

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

No changes since FY2016 — additions, deletions, description changes and billable-status changes are tracked through FY2027 (effective October 1, 2026), 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 N13.6 in its code family, with their registry titles.

View all codes in the N13 family