DxCodebookFY2027 · Oct 1, 2026 – Sep 30, 2027

Category · FY2027

R18 Ascites

  • Header · not billable

R18 is not billable. The category heads 2 billable codes in FY2027: the 2 codes directly below it.

Index → code

  • Hydroperitoneum → R18.8
  • Ascites (abdominal) → R18.8
  • Fluidabdomen → R18.8

Where it sits

  1. Chapter 18 Symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified (R00-R99)
  2. R10-R19 Symptoms and signs involving the digestive system and abdomen (R10-R19)
  3. R18 Ascites
Billable codes
2
Subdivisions
2
CC / MCC codes
2 / 0
HCC V28 codes
1
New FY2027
0
Index entries
9

Codes in R18

  1. R18.0
    Malignant ascites
    BillableCC17
    Code first 3

    Code first

    • malignancy, such as:
    • malignant neoplasm of ovary (C56.-) C56
    • secondary malignant neoplasm of retroperitoneum and peritoneum (C78.6) C78.6
  2. R18.8
    Other ascites
    BillableCC
    Inclusion terms 2

    Inclusion terms

    • Ascites NOS
    • Peritoneal effusion (chronic)

CC/MCC: as a secondary diagnosis, unless the principal diagnosis is on the code’s PDX exclusion list (MS-DRG v44 Appendix C; list on the code card).

Sources of each column.

Instructions

At R18

Includes

  • fluid in peritoneal cavity

Excludes1

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

Notes that also apply

Block R10-R19 instructions (Excludes2 9): printed on the block page.

Chapter 18 instructions (Notes 9, Excludes2 4): printed on the chapter 18 page.

Index entries

  • Ascites (abdominal) → R18.8
  • Hydroperitoneum → R18.8
  • Ascites (abdominal)malignant → R18.0
  • Ascites (abdominal)pseudochylous → R18.8
  • Dropsy, dropsicalabdomen → R18.8
  • Effusionperitoneal (chronic) → R18.8
  • Fluidabdomen → R18.8
  • Fluidperitoneal cavity → R18.8
  • Hydropsabdominis → R18.8

NCHS Alphabetic Index. Index first, then the Tabular List.

Hierarchy