R18

ICD-10Non-billable category

Ascites

Official ICD-10-CM descriptor (FY2026)

Ascites

R18 is a category heading, not a billable code. CMS does not accept it on a claim; report one of the more specific codes beneath it.

Includes

fluid in peritoneal cavity

Excludes1

Not coded here. An Excludes1 code should never be reported at the same time as the code above it.

ascites in alcoholic cirrhosis (K70.31)
ascites in alcoholic hepatitis (K70.11)
ascites in toxic liver disease with chronic active hepatitis (K71.51)

More specific codes under R18

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)

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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.