R18.0 Malignant ascites

The ICD-10-CM code for Malignant ascites is R18.0 (FY2026). It is a billable, claim-ready diagnosis code.

Classification

Chapter

18: Symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified (R00-R99)

Section

R10-R19: Symptoms and signs involving the digestive system and abdomen (R10-R19)

Category R18

3 codes (2 billable)

FY2026 Status

Stable since FY2024

Also Known As

ICD-10-CM Alphabetic Index entries that lead to R18.0:

• Ascites (abdominal) › malignant

U.S. Hospital Utilization

• An estimated 57,860 U.S. inpatient stays in 2023 included R18.0 among the documented diagnoses.

Source: National Inpatient Sample (NIS), Healthcare Cost and Utilization Project (HCUP), Agency for Healthcare Research and Quality, 2016–2023. National survey-weighted estimates.

Official Coding Guidelines

Repeated falls vs history of falling

d. Repeated falls Code R29.6, Repeated falls, is for use for encounters when a patient has recently fallen and the reason for the fall is being investigated. Code Z91.81, History of falling, is for use when a patient has fallen in the past and is at risk for future falls. When appropriate, both codes R29.6 and Z91.81 may be assigned together.

Use of R40.20 unspecified coma; do not report for induced/sedated

e. Coma Code R40.20, Unspecified coma, should be assigned when the underlying cause of the coma is not known, or the cause is a traumatic brain injury and the coma scale is not documented in the medical record. Do not report codes for unspecified coma, individual or total Glasgow coma scale scores for a patient with a medically induced coma or a sedated patient.

Source: CMS — ICD-10-CM Official Guidelines for Coding and Reporting, FY2026

References

• CMS — ICD-10-CM Official Code Set and Guidelines, FY2026
• CDC/NCHS — ICD-10-CM Files and Browser Tool
• AHRQ — HCUP National Inpatient Sample, Frequencies by Diagnosis Code (2016–2023)