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K66.1 ICD-10-CM Code: Hemoperitoneum

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

Coding at a Glance

Tabular directives
2 inclusion terms · 1 Excludes1 · 4 Excludes2

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 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)
  • 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 K66.1 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 K66.1 itself; “inherited from” names the category or block whose note applies here.

Inclusion Terms

Alternative terms the tabular list files under this code.

  • Peritoneal hematoma
  • Peritoneal hemorrhage

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).

Excludes2 — Not Included Here

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

Coder workflow for K66.1

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

Before you code K66.1

  1. Check the Excludes1 note: if the documentation supports a condition named there, do not simply proceed with K66.1. 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 K66.1’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.

    ReviewS36.8

Consider K66.1. 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).

Official instructions as workflow

  • Excludes1 — check before selecting K66.1(1 note)

    Coding workflow: If the documentation supports a condition named in this note, do not simply proceed with K66.1: the two are not reported together. The one exception is when the record shows the two conditions are unrelated to each other.

    CompareS36.8

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

  • Excludes2 — not part of K66.1(4 notes)

    Coding workflow: The conditions named in this note are not included in K66.1. When the record documents both, both may be reported; the note is a boundary, not a prohibition.

    CompareK68.3, R18, R18.8

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

Coding decision scenarios

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

Documentation: Both the condition K66.1 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).

ReviewS36.8

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

Hemoperitoneum is a billable ICD-10-CM diagnosis code (K66.1).

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 (7)

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.

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

  • MCC 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

MS-DRG Grouper Relationships (FY2026)

Potential MS-DRG participation — not a DRG assignment.

FY2026 MS-DRG: MCC — Major 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 1 clinically related codes on its CMS exclusion list.

Named in the grouper logic of 5 MS-DRGs: DRG 393 (MDC 06), DRG 394 (MDC 06), DRG 395 (MDC 06), 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):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).

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, K63.8219 — Small intestinal bacterial overgrowth, unspecified, 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), K66.8 — Other specified disorders of peritoneum, K66.9 — Disorder of peritoneum, unspecified, K68.2 — Retroperitoneal fibrosis, K68.3 — Retroperitoneal hematoma, K68.9 — Other disorders of retroperitoneum, K90.0 — Celiac disease, K90.1 — Tropical sprue, K90.2 — Blind loop syndrome, not elsewhere classified, K90.4 — Other malabsorption due to intolerance, K90.41 — Non-celiac gluten sensitivity, +64 more

Same Index main term, other category

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

J95.01 — Hemorrhage from tracheostomy stoma (from, tracheostomy stoma), K06.8 — Other specified disorders of gingiva and edentulous alveolar ridge (gum), K08.89 — Other specified disorders of teeth and supporting structures (alveolus), K13.79 — Other lesions of oral mucosa (mouth), K14.8 — Other diseases of tongue (tongue), K22.89 — Other specified disease of esophagus (esophagus), K27.4 — Chronic or unspecified peptic ulcer, site unspecified, with hemorrhage (ulcer - code by site under Ulcer, with hemorrhage), K62.5 — Hemorrhage of anus and rectum (anus), K64.5 — Perianal venous thrombosis (perianal), K65.9 — Peritonitis, unspecified (infectional), K68.3 — Retroperitoneal hematoma (retroperitoneal), K6A.8 — Other diseases of the pelvis, not elsewhere classified (pelvis), K76.89 — Other specified diseases of liver (liver), K86.89 — Other specified diseases of pancreas (pancreas), K92.2 — Gastrointestinal hemorrhage, unspecified (colon), L60.8 — Other nail disorders (nail), M27.61 — Osseointegration failure of dental implant (due to or associated with, dental implant), M62.89 — Other specified disorders of muscle (muscle), M79.81 — Nontraumatic hematoma of soft tissue (nontraumatic, muscle), N28.89 — Other specified disorders of kidney and ureter (renal), +182 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.

Partial Thromboplastin Time (PTT) Test, Prothrombin Time Test and INR (PT/INR)

Contextual Map

Every relationship of K66.1 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 K66.1 with these 2 related codes in Claim Check

Hierarchy

Excludes1

Excludes2

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. 5,744 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

  • Hematoma (traumatic) (skin surface intact), peritoneal[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
  • Hemoperitoneum[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
  • Hemorrhage, hemorrhagic (concealed), intrapelvic, male[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
  • Hemorrhage, hemorrhagic (concealed), intraperitoneal[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
  • Hemorrhage, hemorrhagic (concealed), mesentery[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
  • Hemorrhage, hemorrhagic (concealed), omentum[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
  • Hemorrhage, hemorrhagic (concealed), peritoneum, peritoneal[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026

Nearest codes

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
Coding guidelines Official source data
ICD-10-CM Official Guidelines for Coding and Reporting (FY2026), quoted by section 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. "K66.1 — Hemoperitoneum." ICD-10-CM FY2026. https://medcoder.ai/icd10/code/k66.1-hemoperitoneum

Change history

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

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 K66.1 in its code family, with their registry titles.

View all codes in the K66 family