ICD-10 R18.0
Billable / Specific CCMalignant ascites
About ICD-10-CM R18.0
ICD-10-CM code R18.0 represents Malignant ascites. This is a billable/specific code in the Symptoms, Signs, and Abnormal Findings chapter (block R18). The 2026 edition of ICD-10-CM R18.0 became effective on October 1, 2025.
Coding Tips for R18.0
Specialist guidance from the PayerReady Medical Coding Team. Specificity warnings, HCC capture rules, sequencing notes.
R18.0 is designated CC for MS-DRG grouping. On inpatient claims, this code can shift the DRG to the with-CC variant when documented as a present-on-admission secondary diagnosis. Hospital CDI programs flag CC opportunities during chart review. Failure to capture this code may leave 30 to 80 percent of the inpatient stay revenue unrealized.
Coding Notes
Code First
- malignancy, such as:
- malignant neoplasm of ovary (C56.-)
- secondary malignant neoplasm of retroperitoneum and peritoneum (C78.6)
Inpatient DRG Impact, CC
codes Malignant ascites. As a Complication/Comorbidity (CC), this contributes to DRG severity adjustment when documented alongside the principal diagnosis.
Medicare LCD Coverage for R18.0
Local Coverage Determinations (LCDs) from CMS MACs that list R18.0 as a covered diagnosis.
Showing top 10 of 100 total . Click a CPT for full coverage scope.
Commercial Payer Coverage
Coverage policies from major commercial payers referencing R18.0.
5 Medicare
CPT Codes Commonly Billed with R18.0
Procedures frequently paired with this diagnosis based on PayerReady's Dx↔Px linkage data.
We don't have CPT pairings indexed for this specific code yet. Use the CPT search above to find common procedures, or check your payer's published medical policy for code-specific guidance.
Convert R18.0 to ICD-9-CM
Per CMS General Equivalence Mappings (GEMs), useful for legacy data review and historical claim analysis.
| ICD-10 | ICD-9 | Mapping Flags |
|---|---|---|
| R18.0 | 78951 | 00000 |
Flags format (5 digits): Approximate · No Map · Combination · Scenario · Choice List. Source: CMS 2017 GEMs (final version).
Codes Adjacent To R18.0
Other codes in section R10-R19 (Symptoms and signs involving the digestive system and abdomen).
ICD-10 R18.0, Billing FAQ
Is ICD-10 code R18.0 billable? +
Yes, R18.0 is a billable ICD-10-CM code that can appear as a primary or secondary diagnosis on claims.
Is R18.0 a CC or MCC for inpatient DRG? +
Yes, this code is designated as CC. Documenting as a secondary diagnosis on inpatient claims can shift the DRG to a higher-weighted category.
What ICD-9 codes does R18.0 map to? +
Per CMS GEMs, R18.0 maps to ICD-9 codes: 78951. Useful for legacy data review and historical claim analysis.
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Reviewed by the PayerReady Medical Coding Team
Verified against the CMS 2026 code set on May 31, 2026.
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