Is R18.0 a billable ICD-10-CM code?

Yes. R18.0 is a billable, specific ICD-10-CM code and is valid for submission on a claim.

Where does R18.0 sit in the tabular list?

Symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified (R00-R99), in the block Symptoms and signs involving the digestive system and abdomen (R10-R19).

What cannot be coded together with R18.0?

R18.0 carries Excludes1 notes, which means the conditions they list can never be coded together with it on the same encounter. Some are written on the categories above R18.0 (R18) and apply to it just the same.

R18.0

R18.0 — Malignant ascites

Billable / specific codeICD-10-CM

R18.0 is a billable, specific ICD-10-CM code for malignant ascites. It is valid for submission on a claim.

Code first

The underlying condition must be sequenced before this code.

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

Excludes1 inherited from the categories above R18.0

These are not written on R18.0, but they bind it: a note on a category applies to every code beneath it. Billing R18.0 with anything listed here is a denial.

Written on R18 — Ascites

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

Other codes that can never be billed with R18.0

These codes carry an Excludes1 note pointing at R18.0. The conflict binds both ways, but ICD-10-CM only writes it down on one side — so you would not find this by reading R18.0 alone.

R60Edema, not elsewhere classified
R19.0Intra-abdominal and pelvic swelling, mass and lump

Risk adjustment

R18.0 risk-adjusts. Under the CMS-HCC V28 model it maps to this category:

HCC 17 Cancer Metastatic to Lung, Liver, Brain, and Other Organs; Acute Myeloid Leukemia Except Promyelocytic4.209 RAF

Coefficient shown for the Community Non-dual Aged segment. A higher HCC in the same hierarchy will suppress this one, so capturing it does not always add score.

Medicare coverage

R18.0 is named in 7 Medicare coverage policies — 7 listing it as supporting medical necessity. Which of them applies to you depends on your Medicare contractor, and coverage genuinely differs by state.

A56421Billing and Coding: CT of the Abdomen and Pelvis
A56464Billing and Coding: Flow Cytometry
A56697Billing and Coding: Non-Invasive Vascular Studies
A56758Billing and Coding: Non-Invasive Vascular Studies

How R18.0 is indexed

Coders do not find codes by browsing the tabular list — they look them up in the alphabetic index, under the word the physician wrote. These are the index entries that lead here, so you can see which chart wordings map to R18.0.

Ascites›malignant

Code history

R18.0 has not changed since FY2024 — no addition, revision or deletion across the three most recent ICD-10-CM releases.

Related codes at this level

Codes that share R18. If R18.0 is not quite right, the correct code is usually one of these.

R18.8Other ascites

Questions about R18.0

Is R18.0 a billable ICD-10-CM code?: Yes. R18.0 is a billable, specific ICD-10-CM code and is valid for submission on a claim.
Where does R18.0 sit in the tabular list?: Symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified (R00-R99), in the block Symptoms and signs involving the digestive system and abdomen (R10-R19).
What cannot be coded together with R18.0?: R18.0 carries Excludes1 notes, which means the conditions they list can never be coded together with it on the same encounter. Some are written on the categories above R18.0 (R18) and apply to it just the same.