R18.0

ICD-10Billable

Malignant ascites

Official ICD-10-CM descriptor (FY2026)

Malignant ascites

R18.0 is valid for submission on a claim — CMS flags it as a billable, specific code.

Code first

Sequence the underlying condition before this code.

malignancy, such as:
malignant neoplasm of ovary (C56.-)
secondary malignant neoplasm of retroperitoneum and peritoneum (C78.6)

Related codes in R18

R18.8Other ascites

Where this code sits

Chapter: 18. Symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified (R00-R99)
Block: Symptoms and signs involving the digestive system and abdomen (R10-R19)
Parent code: R18

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Source

ICD-10-CM FY2026. Centers for Medicare & Medicaid Services (CMS) / National Center for Health Statistics (NCHS), “2026 ICD-10-CM Code Descriptions in Tabular Order” (icd10cm_order_2026.txt). Download the original file from cms.gov. Public domain (US Government work). Descriptors, billable flags and instructional notes on this page are reproduced from that file without modification. Krasyn adds no clinical guidance.