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R18.8 ICD-10-CM Code: Other ascites

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

Coding at a Glance

Tabular directives
3 inclusion terms · 3 Excludes1 · 9 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 v44, Appendix B.

  • MS-DRG 947 — SIGNS AND SYMPTOMS WITH MCC (MDC 23)
  • MS-DRG 948 — SIGNS AND SYMPTOMS WITHOUT MCC (MDC 23)

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 R18.8 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 R18.8 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.

  • fluid in peritoneal cavity

Source: inherited from R18

Inclusion Terms

Alternative terms the tabular list files under this code.

  • Ascites NOS
  • Peritoneal effusion (chronic)

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 R18

Excludes2 — Not Included Here

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

Source: inherited from R10-R19

Coder workflow for R18.8

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

Before you code R18.8

  1. Check whether an established diagnosis that explains this sign or symptom is documented. If one is, review whether the documented diagnosis changes the coding pathway: a symptom that is integral to a confirmed diagnosis is not reported separately, while one not routinely associated with it may be. Signs and symptoms are reported when no definitive diagnosis is established (Guidelines I.B.4, I.B.5, I.B.6, I.C.18.b).

    Guide: Symptom code vs confirmed diagnosis →

  2. “Other” (NEC) means the condition is specified in the record but no dedicated code captures it. Confirm the documented form is not one a sibling code names before settling on R18.8; if the record states no specifics at all, the unspecified sibling applies instead. “Other” codes are for documented conditions the classification gives no specific code; “unspecified” codes are for records lacking the detail (Guidelines I.A.9.a, I.A.9.b).

    ReviewR18.0

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

  3. Check the Excludes1 note: if the documentation supports a condition named there, do not simply proceed with R18.8. 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. Is an established diagnosis that explains this sign or symptom documented?
    Yes → Review whether the documented diagnosis changes the coding pathway: a symptom integral to it is not reported separately.
    No → Continue — the sign or symptom code stands when no definitive diagnosis is established.
  2. Does the documentation support a condition named in R18.8’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.

    ReviewK70.31, K70.11, K71.51

Consider R18.8. 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).
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.

Official instructions as workflow

  • Excludes1 — check before selecting R18.8(3 notes)

    Coding workflow: If the documentation supports a condition named in this note, do not simply proceed with R18.8: the two are not reported together. The one exception is when the record shows the two conditions are unrelated to each other.

    CompareK70.31, K70.11, K71.51

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

  • Excludes2 — not part of R18.8(9 notes)

    Coding workflow: The conditions named in this note are not included in R18.8. When the record documents both, both may be reported; the note is a boundary, not a prohibition.

    CompareQ40.0, K56, P76, K31.3, N94

    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: The sign or symptom is documented, and the same record establishes a diagnosis that routinely includes it.

Coding question: Is R18.8 reported in addition to the diagnosis?

Path: Review the documented diagnosis and whether the classification treats this finding as integral to it.

Reason: Signs and symptoms integral to a confirmed diagnosis are not coded separately; those not routinely associated with it may be reported when present (Guidelines I.B.5, I.B.6, I.C.18.b).

Documentation: Both the condition R18.8 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).

ReviewK70.31, K70.11, K71.51

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 R18.8 with…

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

The codes most likely to be picked instead of R18.8 — 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.

  • K70.31— Excludes1 conflict (Excludes1 — generally not reported together)

    Not coded here — the tabular list excludes this pair for the same encounter.

    Not reported together with this code, except where the two conditions are documented as unrelated.

    What moves you there: Documentation of ascites in alcoholic cirrhosis moves the case to K70.31; the two are not reported together unless documented as unrelated.

    Full comparison: R18.8 vs K70.31 →

  • K70.11— Excludes1 conflict (Excludes1 — generally not reported together)

    Not coded here — the tabular list excludes this pair for the same encounter.

    Not reported together with this code, except where the two conditions are documented as unrelated.

    What moves you there: Documentation of ascites in alcoholic hepatitis moves the case to K70.11; the two are not reported together unless documented as unrelated.

    Full comparison: R18.8 vs K70.11 →

  • K71.51— Excludes1 conflict (Excludes1 — generally not reported together)

    Not coded here — the tabular list excludes this pair for the same encounter.

    Not reported together with this code, except where the two conditions are documented as unrelated.

    What moves you there: Documentation of ascites in toxic liver disease with chronic active hepatitis moves the case to K71.51; the two are not reported together unless documented as unrelated.

    Full comparison: R18.8 vs K71.51 →

  • Q40.0— 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 congenital or infantile pylorospasm adds Q40.0; it is not part of this code and both may be reported when both are documented.

    Full comparison: R18.8 vs Q40.0 →

  • K92.0— 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 gastrointestinal hemorrhage adds K92.0; it is not part of this code and both may be reported when both are documented.

    Full comparison: R18.8 vs K92.0 →

  • K92.2— 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 gastrointestinal hemorrhage adds K92.2; it is not part of this code and both may be reported when both are documented.

    Full comparison: R18.8 vs K92.2 →

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.

Code Overview

Other ascites is a billable ICD-10-CM diagnosis code (R18.8).

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 (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.

Verify Before Coding

  • CC as a secondary diagnosis (FY2027). 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 R18.8 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 2 Excludes1 notes: R19.0 — Intra-abdominal and pelvic swelling, mass and lump (via R18.-), R60 — Edema, not elsewhere classified (via R18.-).

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

Referenced by 2 Excludes2 notes: K66 — Other disorders of peritoneum (via R18.-), K66 — Other disorders of peritoneum.

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

Referenced by 3 Use Additional Code instructions across 2 chapters: B18 — Chronic viral hepatitis, K72 — Hepatic failure, not elsewhere classified, K73 — Chronic hepatitis, not elsewhere classified.

These codes instruct coders to additionally report this code when it applies.

MS-DRG Grouper Relationships (FY2027)

Potential MS-DRG participation — not a DRG assignment.

FY2027 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 57 clinically related codes on its CMS exclusion list.

Named in the grouper logic of 2 MS-DRGs: DRG 947 (MDC 23), DRG 948 (MDC 23).

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

Clinical classification (AHRQ CCSR):SYM006 — Abdominal pain and other digestive/abdomen signs and symptoms (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.

G89.0 — Central pain syndrome, G89.11 — Acute pain due to trauma, G89.12 — Acute post-thoracotomy pain, G89.18 — Other acute postprocedural pain, G89.21 — Chronic pain due to trauma, G89.22 — Chronic post-thoracotomy pain, G89.28 — Other chronic postprocedural pain, G89.29 — Other chronic pain, G89.3 — Neoplasm related pain (acute) (chronic), G89.4 — Chronic pain syndrome, R19.00 — Intra-abdominal and pelvic swelling, mass and lump, unspecified site, R19.01 — Right upper quadrant abdominal swelling, mass and lump, R19.02 — Left upper quadrant abdominal swelling, mass and lump, R19.03 — Right lower quadrant abdominal swelling, mass and lump, R19.04 — Left lower quadrant abdominal swelling, mass and lump, R19.05 — Periumbilic swelling, mass or lump, R19.06 — Epigastric swelling, mass or lump, R19.07 — Generalized intra-abdominal and pelvic swelling, mass and lump, R19.09 — Other intra-abdominal and pelvic swelling, mass and lump, R19.30 — Abdominal rigidity, unspecified site, +36 more

Same clinical category (CCSR)

AHRQ's Clinical Classifications Software groups these diagnoses under the same clinical category (Abdominal pain and other digestive/abdomen signs and symptoms).

R14.3 — Flatulence, R15.0 — Incomplete defecation, R15.1 — Fecal smearing, R15.2 — Fecal urgency, R15.9 — Full incontinence of feces, R16.0 — Hepatomegaly, not elsewhere classified, R16.1 — Splenomegaly, not elsewhere classified, R16.2 — Hepatomegaly with splenomegaly, not elsewhere classified, R17 — Unspecified jaundice, R18.0 — Malignant ascites, R19.00 — Intra-abdominal and pelvic swelling, mass and lump, unspecified site, R19.01 — Right upper quadrant abdominal swelling, mass and lump, R19.02 — Left upper quadrant abdominal swelling, mass and lump, R19.03 — Right lower quadrant abdominal swelling, mass and lump, R19.04 — Left lower quadrant abdominal swelling, mass and lump, R19.05 — Periumbilic swelling, mass or lump, R19.06 — Epigastric swelling, mass or lump, R19.07 — Generalized intra-abdominal and pelvic swelling, mass and lump, R19.09 — Other intra-abdominal and pelvic swelling, mass and lump, R19.11 — Absent bowel sounds, +58 more

Same Index main term, other category

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

K71.51 — Toxic liver disease with chronic active hepatitis with ascites (due to, hepatitis, chronic active, with toxic liver disease), K73.2 — Chronic active hepatitis, not elsewhere classified (due to, hepatitis, chronic active), K82.1 — Hydrops of gallbladder (gallbladder), M25.40 — Effusion, unspecified joint (joint), M25.41 — Effusion, shoulder (joint, shoulder), M25.42 — Effusion, elbow (joint, elbow), M25.43 — Effusion, wrist (joint, wrist), M25.44 — Effusion, hand (joint, hand joint), M25.45 — Effusion, hip (joint, hip), M25.46 — Effusion, knee (joint, knee), M25.47 — Effusion, ankle and foot (joint, ankle), M25.48 — Effusion, other site (joint, specified joint NEC), M32.13 — Lung involvement in systemic lupus erythematosus (pleura, pleurisy, pleuritic, pleuropericardial, due to systemic lupus erythematosis), O66.3 — Obstructed labor due to other abnormalities of fetus (causing obstructed labor), P28.89 — Other specified respiratory conditions of newborn (pleura, pleurisy, pleuritic, pleuropericardial, newborn), P56.0 — Hydrops fetalis due to isoimmunization (fetalis, due to, isoimmunization), P56.90 — Hydrops fetalis due to unspecified hemolytic disease (fetalis, due to, hemolytic disease), P56.99 — Hydrops fetalis due to other hemolytic disease (fetalis, due to, hemolytic disease, specified NEC), P83.2 — Hydrops fetalis not due to hemolytic disease (newborn), R60.9 — Edema, unspecified, +22 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), Prothrombin Time Test and INR (PT/INR), Thyroid Stimulating Hormone (TSH)

Contextual Map

Every relationship of R18.8 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 R18.8 with these 6 related codes in Claim Check

Hierarchy

Referenced by Excludes1 notes

Referenced by Excludes2 notes

Referenced by Use Additional Code instructions

Clinical classification (CCSR)

MS-DRG Grouper

  • CC — Complication or Comorbidity [MS-DRG severity]: “As a secondary diagnosis this code can raise the stay's MS-DRG severity tier (CC).”— CMS MS-DRG Definitions Manual (Appendix C) · FY2027
  • DRG 947 — SIGNS AND SYMPTOMS WITH MCC[MS-DRG]: “SIGNS AND SYMPTOMS WITH MCC (MDC 23)”— CMS MS-DRG Definitions Manual (Appendix B) · FY2027
  • DRG 948 — SIGNS AND SYMPTOMS WITHOUT MCC[MS-DRG]: “SIGNS AND SYMPTOMS WITHOUT MCC (MDC 23)”— CMS MS-DRG Definitions Manual (Appendix B) · FY2027

MDC crossing

  • MDC 23 — Factors Influencing Health Status and Other Contacts with Health Services[MDC crossing]: “Factors Influencing Health Status and Other Contacts with Health Services — 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. 1,258 same-MDC procedures group here; browse them on the MDC page.”— CMS MS-DRG Definitions Manual · FY2027

Index entries

  • Ascites (abdominal)[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2027
  • Ascites (abdominal), pseudochylous[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2027
  • Dropsy, dropsical, abdomen[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2027
  • Effusion, peritoneal (chronic)[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2027
  • Fluid, abdomen[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2027
  • Fluid, peritoneal cavity[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2027
  • Hydroperitoneum[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2027
  • Hydrops, abdominis[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

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 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. "R18.8 — Other ascites." ICD-10-CM FY2027. https://medcoder.ai/icd10/code/r18.8-other-ascites

Change history

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

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 R18.8 in its code family, with their registry titles.

View all codes in the R18 family