ICD-10-CM 2027
ICD-10 code for malignant ascites
From the official ICD-10-CM alphabetic index entry “Ascites (abdominal) › malignant”. Page updated September 29, 2026.
About coding malignant ascites
The ICD-10-CM code for malignant ascites is R18.0 (Malignant ascites).
Within R18 (ascites), R18.0 is specifically for malignant ascites. Related codes cover other ascites (R18.8).
Code first malignancy, such as: malignant neoplasm of ovary (C56.-) and secondary malignant neoplasm of retroperitoneum and peritoneum (C78.6).
As a secondary diagnosis it is a CC (complication or comorbidity), which can move an inpatient stay into the "with CC" MS-DRG of its family, unless the principal diagnosis excludes it.
Common questions about malignant ascites ICD-10 codes
What is the ICD-10 code for malignant ascites?
- R18.0 — Malignant ascites.
Is R18.0 billable?
- Yes. R18.0 is a billable/specific ICD-10-CM code valid for FY2027 (October 1, 2026 – September 30, 2027).
Can R18.0 be used as a principal diagnosis?
- No. It is not acceptable as the principal diagnosis for an inpatient stay; it may be reported as a secondary diagnosis.
Is R18.0 a CC or MCC?
- R18.0 is a CC (complication or comorbidity) under MS-DRG v44.0, unless excluded by the principal diagnosis.