R18 – Ascites

ICD-10-CM 2027 diagnosis code · Symptoms and signs involving the digestive system and abdomen

Non-billable header

ICD-10-CM code R18

Code: R18 (claims format: R18)
Description: Ascites
Billable: No – use a more specific code below
Valid for: Dates of service October 1, 2026 – September 30, 2027 (FY2027)
Chapter: 18. Symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified (R00-R99)
Block: R10-R19 Symptoms and signs involving the digestive system and abdomen

Billable codes under R18

R18 is a header code and cannot be used on claims. Choose the most specific code:

R18.0 – Malignant ascitesBillable
R18.8 – Other ascitesBillable

Notes for R18

Includes:

fluid in peritoneal cavity

Excludes1 (not coded here):

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

Notes inherited from parent codes

Instructional notes at a category or block level apply to every code below it.

Block R10-R19

Excludes2 (not included here):

congenital or infantile pylorospasm (Q40.0)
gastrointestinal hemorrhage (K92.0-K92.2)
intestinal obstruction (K56.-)
newborn gastrointestinal hemorrhage (P54.0-P54.3)
newborn intestinal obstruction (P76.-)
pylorospasm (K31.3)
signs and symptoms involving the urinary system (R30-R39)
symptoms referable to female genital organs (N94.-)
symptoms referable to male genital organs (N48-N50)

Frequently asked questions

What is ICD-10 code R18?

R18 is the ICD-10-CM code for ascites, in the block R10-R19 (Symptoms and signs involving the digestive system and abdomen).

Is R18 a billable code?

No. R18 is a header code with more specific child codes; report one of the billable codes listed above.

Source: CDC/NCHS ICD-10-CM FY2027 code files, tabular list and index. Reference only – code assignment must follow the official ICD-10-CM guidelines and documentation in the medical record.