2022 ICD-10-CM Diagnosis Code R18.0

Malignant ascites

    2016 2017 2018 2019 2020 2021 2022 Billable/Specific Code
  • R18.0 is a billable/specific ICD-10-CM code that can be used to indicate a diagnosis for reimbursement purposes.
  • The 2022 edition of ICD-10-CM R18.0 became effective on October 1, 2021.
  • This is the American ICD-10-CM version of R18.0 - other international versions of ICD-10 R18.0 may differ.
Code First
Code First Help
Certain conditions have both an underlying etiology and multiple body system manifestations due to the underlying etiology. For such conditions, ICD-10-CM has a coding convention that requires the underlying condition be sequenced first followed by the manifestation. Wherever such a combination exists there is a "use additional code" note at the etiology code, and a "code first" note at the manifestation code. These instructional notes indicate the proper sequencing order of the codes, etiology followed by manifestation. In most cases the manifestation codes will have in the code title, "in diseases classified elsewhere." Codes with this title are a component of the etiology/manifestation convention. The code title indicates that it is a manifestation code. "In diseases classified elsewhere" codes are never permitted to be used as first listed or principle diagnosis codes. They must be used in conjunction with an underlying condition code and they must be listed following the underlying condition.
  • malignancy, such as:
  • malignant neoplasm of ovary (
    ICD-10-CM Diagnosis Code C56
    • C56 Malignant neoplasm of ovary
      • C56.1 Malignant neoplasm of right ovary
      • C56.2 Malignant neoplasm of left ovary
      • C56.3 Malignant neoplasm of bilateral ovaries
      • C56.9 Malignant neoplasm of unspecified ovary
  • secondary malignant neoplasm of retroperitoneum and peritoneum (
    ICD-10-CM Diagnosis Code C78.6

    Secondary malignant neoplasm of retroperitoneum and peritoneum

      2016 2017 2018 2019 2020 2021 2022 Billable/Specific Code
The following code(s) above R18.0 contain annotation back-references
Annotation Back-References
In this context, annotation back-references refer to codes that contain:
  • Applicable To annotations, or
  • Code Also annotations, or
  • Code First annotations, or
  • Excludes1 annotations, or
  • Excludes2 annotations, or
  • Includes annotations, or
  • Note annotations, or
  • Use Additional annotations
that may be applicable to R18.0:
  • R00-R99
    2022 ICD-10-CM Range R00-R99

    Symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified

    • This chapter includes symptoms, signs, abnormal results of clinical or other investigative procedures, and ill-defined conditions regarding which no diagnosis classifiable elsewhere is recorded.
    • Signs and symptoms that point rather definitely to a given diagnosis have been assigned to a category in other chapters of the classification. In general, categories in this chapter include the less well-defined conditions and symptoms that, without the necessary study of the case to establish a final diagnosis, point perhaps equally to two or more diseases or to two or more systems of the body. Practically all categories in the chapter could be designated 'not otherwise specified', 'unknown etiology' or 'transient'. The Alphabetical Index should be consulted to determine which symptoms and signs are to be allocated here and which to other chapters. The residual subcategories, numbered .8, are generally provided for other relevant symptoms that cannot be allocated elsewhere in the classification.
    • The conditions and signs or symptoms included in categories R00-R94 consist of:
    • (a) cases for which no more specific diagnosis can be made even after all the facts bearing on the case have been investigated;
    • (b) signs or symptoms existing at the time of initial encounter that proved to be transient and whose causes could not be determined;
    • (c) provisional diagnosis in a patient who failed to return for further investigation or care;
    • (d) cases referred elsewhere for investigation or treatment before the diagnosis was made;
    • (e) cases in which a more precise diagnosis was not available for any other reason;
    • (f) certain symptoms, for which supplementary information is provided, that represent important problems in medical care in their own right.
    Type 2 Excludes
    • abnormal findings on antenatal screening of mother (O28.-)
    • certain conditions originating in the perinatal period (P04-P96)
    • signs and symptoms classified in the body system chapters
    • signs and symptoms of breast (N63, N64.5)
    Symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified
  • R10-R19
    2022 ICD-10-CM Range R10-R19

    Symptoms and signs involving the digestive system and abdomen

    Type 2 Excludes
    • 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)
    Symptoms and signs involving the digestive system and abdomen
  • R18
    ICD-10-CM Diagnosis Code R18


      2016 2017 2018 2019 2020 2021 2022 Non-Billable/Non-Specific Code
    • fluid in peritoneal cavity
    Type 1 Excludes
    • ascites in alcoholic cirrhosis (K70.31)
    • ascites in alcoholic hepatitis (K70.11)
    • ascites in toxic liver disease with chronic active hepatitis (K71.51)
Clinical Information
  • A condition in which fluid containing cancer cells collects in the abdomen.
  • Accumulation of fluid in the peritoneal cavity resulting from the growth of primary or metastatic malignant neoplasms in the peritoneum.
  • Effusion and accumulation of cancerous serous fluid within the peritoneal cavity.
ICD-10-CM R18.0 is grouped within Diagnostic Related Group(s) (MS-DRG v39.0):
  • 947 Signs and symptoms with mcc
  • 948 Signs and symptoms without mcc

Convert R18.0 to ICD-9-CM

Code History
  • 2016 (effective 10/1/2015): New code (first year of non-draft ICD-10-CM)
  • 2017 (effective 10/1/2016): No change
  • 2018 (effective 10/1/2017): No change
  • 2019 (effective 10/1/2018): No change
  • 2020 (effective 10/1/2019): No change
  • 2021 (effective 10/1/2020): No change
  • 2022 (effective 10/1/2021): No change

Diagnosis Index entries containing back-references to R18.0:
  • Ascites (abdominal) R18.8
    ICD-10-CM Diagnosis Code R18.8

    Other ascites

      2016 2017 2018 2019 2020 2021 2022 Billable/Specific Code
    Applicable To
    • Ascites NOS
    • Peritoneal effusion (chronic)
    • malignant R18.0

ICD-10-CM Codes Adjacent To R18.0
R15.0 Incomplete defecation
R15.1 Fecal smearing
R15.2 Fecal urgency
R15.9 Full incontinence of feces
R16 Hepatomegaly and splenomegaly, not elsewhere classified
R16.0 Hepatomegaly, not elsewhere classified
R16.1 Splenomegaly, not elsewhere classified
R16.2 Hepatomegaly with splenomegaly, not elsewhere classified
R17 Unspecified jaundice
R18 Ascites
R18.0 Malignant ascites
R18.8 Other ascites
R19 Other symptoms and signs involving the digestive system and abdomen
R19.0 Intra-abdominal and pelvic swelling, mass and lump
R19.00 …… unspecified site
R19.01 Right upper quadrant abdominal swelling, mass and lump
R19.02 Left upper quadrant abdominal swelling, mass and lump
R19.03 Right lower quadrant abdominal swelling, mass and lump
R19.04 Left lower quadrant abdominal swelling, mass and lump
R19.05 Periumbilic swelling, mass or lump
R19.06 Epigastric swelling, mass or lump

Reimbursement claims with a date of service on or after October 1, 2015 require the use of ICD-10-CM codes.