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K63.8219 ICD-10-CM Code: Small intestinal bacterial overgrowth, unspecified

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

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; the Instructions section marks which is which.

The tabular list publishes no instructional note for this code itself.

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.

  • MS-DRG 393 — OTHER DIGESTIVE SYSTEM DIAGNOSES WITH MCC (MDC 06)
  • MS-DRG 394 — OTHER DIGESTIVE SYSTEM DIAGNOSES WITH CC (MDC 06)
  • MS-DRG 395 — OTHER DIGESTIVE SYSTEM DIAGNOSES WITHOUT CC/MCC (MDC 06)

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.

7th Character Guide

  • 1 — hydrogen-subtype
  • 2 — hydrogen sulfide-subtype
  • 9 — unspecified (this page’s code)

Variant codes in this family

K63.8211, K63.8212, K63.8219

Character meanings are CMS's official 7th-character extensions for this family, as carried in each variant code's official description; variant codes are registry rows. The explanation of how the encounter character is assigned is MedCoder editorial, distinct from the official content above it.

Coder workflow for K63.8219

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

Before you code K63.8219

  1. Unspecified does not mean incorrect. When the record gives no greater specificity, K63.8219 may be the appropriate code. Check the record for detail that supports a more specific sibling. An unspecified code is for records that do not provide the detail a more specific code needs; a query, not an assumption, is the route to specificity (Guidelines I.A.9.b, I.B.18).

    See the relationships section · Guide: Other vs unspecified (NEC vs NOS) →

  2. A 7th character is required in this family. Confirm the documentation supports the character assigned — its meaning in this family is defined in the official instruction. This page’s code carries “9”. The official 7th-character definitions for this family are quoted in the guide.

    See the 7th Character Guide

Choose the right path

  1. Does the record document the detail a more specific sibling code needs?
    Yes → Review the specific siblings in this subcategory.
    No → Continue — K63.8219 is appropriate when the documentation goes no further.
  2. Does the documentation support one of this family’s 7th-character values?
    Yes → Assign the matching 7th character; the variant codes are in the 7th Character Guide.
    No → The code is invalid without its 7th character — query for the missing element.

Consider K63.8219. Then 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).
7th-character basis
The documented element this family’s 7th character records (see the official definitions in the 7th Character Guide).
Any detail beyond this code’s title
What the record states that a more specific sibling code would capture — or its absence, which itself supports the unspecified code.

Coding decision scenarios

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

Documentation: The provider documents the condition in the terms of this code’s title and records no further detail.

Coding question: Is a more specific sibling code supportable?

Path: Review the subcategory for a sibling that names the missing detail.

Reason: A more specific code needs documentation of the distinguishing element; without it the unspecified code is appropriate, and a provider query is the route to specificity (Guidelines I.A.9.b, I.B.18).

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 K63.8219 with…

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

The codes most likely to be picked instead of K63.8219 — 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.

  • K63.8211— Encounter relationship (Review)

    Same underlying diagnosis, different encounter phase.

    The same diagnosis at a different phase of care; one encounter takes one 7th character.

    What moves you there: Documentation of a hydrogen-subtype moves the case to K63.8211.

    Full comparison: K63.8219 vs K63.8211 →

  • K63.8212— Encounter relationship (Review)

    Same underlying diagnosis, different encounter phase.

    The same diagnosis at a different phase of care; one encounter takes one 7th character.

    What moves you there: Documentation of a hydrogen sulfide-subtype moves the case to K63.8212.

    Full comparison: K63.8219 vs K63.8212 →

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

Small intestinal bacterial overgrowth, unspecified is a billable ICD-10-CM diagnosis code (K63.8219).

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

Official Coding Guidelines

No excerpt in the ICD-10-CM Official Guidelines names this code specifically. Its chapter carries only this chapter-wide note:

Chapter 11: Diseases of the Digestive System (K00-K95)

Reserved for future guideline expansion

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

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 3 MS-DRGs: DRG 393 (MDC 06), DRG 394 (MDC 06), DRG 395 (MDC 06).

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

Clinical classification (AHRQ CCSR):DIG025 — Other specified and unspecified gastrointestinal disorders (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 (Other specified and unspecified gastrointestinal disorders).

K59.8 — Other specified functional intestinal disorders, K59.81 — Ogilvie syndrome, K59.89 — Other specified functional intestinal disorders, K59.9 — Functional intestinal disorder, unspecified, K63.2 — Fistula of intestine, K63.3 — Ulcer of intestine, K63.4 — Enteroptosis, K63.81 — Dieulafoy lesion of intestine, K63.8211 — Small intestinal bacterial overgrowth, hydrogen-subtype, K63.8212 — Small intestinal bacterial overgrowth, hydrogen sulfide-subtype, K63.822 — Small intestinal fungal overgrowth, K63.829 — Intestinal methanogen overgrowth, unspecified, K63.89 — Other specified diseases of intestine, K63.9 — Disease of intestine, unspecified, K66.0 — Peritoneal adhesions (postprocedural) (postinfection), K66.1 — Hemoperitoneum, K66.8 — Other specified disorders of peritoneum, K66.9 — Disorder of peritoneum, unspecified, K68.2 — Retroperitoneal fibrosis, K68.3 — Retroperitoneal hematoma, +64 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.

Fecal Occult Blood Test (FOBT)

Contextual Map

Every relationship of K63.8219 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.

Hierarchy

Clinical classification (CCSR)

MS-DRG Grouper

MDC crossing

  • MDC 06 — Diseases and Disorders of the Digestive System[MDC crossing]: “Diseases and Disorders of the Digestive System — 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. 5,748 same-MDC procedures group here; browse them on the MDC page.”— CMS MS-DRG Definitions Manual · FY2027

Index entries

  • Overgrowth, bacterial, small intestinal[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2027

Nearest codes (17)

Change history

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 (1)

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
Coding guidelines Official source data
ICD-10-CM Official Guidelines for Coding and Reporting (FY2027), quoted by section 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 20, 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. "K63.8219 — Small intestinal bacterial overgrowth, unspecified." ICD-10-CM FY2027. https://medcoder.ai/icd10/code/k63.8219-small-intestinal-bacterial-overgrowth-unspecified

Change history

  • FY2024 — October 1, 2023
    Added to the code set
    Small intestinal bacterial overgrowth, unspecified
    FY2024 changes

Nearest Codes in This Family

Official ICD-10-CM classifications closest to K63.8219 in its code family, with their registry titles.

View all codes in the K63 family