Billable ICD-10-CM code, FY2026. Acts as a Complication or Comorbidity (CC) as a secondary diagnosis.
Code first
malignancy, such as:
malignant neoplasm of ovary (C56.-)
secondary malignant neoplasm of retroperitoneum and peritoneum (C78.6)
Applies from R18 Ascites
Includes
fluid in peritoneal cavity
Excludes1 (never code together)
ascites in alcoholic cirrhosis (K70.31)
ascites in alcoholic hepatitis (K70.11)
ascites in toxic liver disease with chronic active hepatitis (K71.51)
Risk adjustment (HCC)
CMS-HCC V28: HCC 17 — Cancer Metastatic to Lung, Liver, Brain, and Other Organs; Acute Myeloid Leukemia Except Promyelocytic
MS-DRG index
Defines the logic of DRG(s) 947-948 in MDC 23.
Approximate ICD-9-CM (GEMs)
789.51 Malignant ascites
Medicare Code Edits (MCE v43.1 (April 2026))
Unacceptable principal diagnosis: These codes describe a circumstance which influences care but is not a current illness or injury, or capture only an underlying condition, and are unacceptable as principal diagnosis.
Code annotations containing back-references to R18.0
Back-references to R18
Type 2 Excludes: K66 Other disorders of peritoneum ("ascites (R18.-)")
Type 1 Excludes: R19.0 Intra-abdominal and pelvic swelling, mass and lump ("ascites (R18.-)")
Type 1 Excludes: R60 Edema, not elsewhere classified ("ascites (R18.-)")