Version 2024
No Valid Principal Dx

2024 ICD-10-CM Diagnosis Code R18


ICD-10-CM Code:
ICD-10 Code for:
Is Billable?
Not Valid for Submission
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Code Classification

  • Symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified
    • Symptoms and signs involving the digestive system and abdomen
      • Ascites

R18 is a non-specific and non-billable diagnosis code code, consider using a code with a higher level of specificity for a diagnosis of ascites. The code is not specific and is NOT valid for the year 2024 for the submission of HIPAA-covered transactions. Category or Header define the heading of a category of codes that may be further subdivided by the use of 4th, 5th, 6th or 7th characters.

According to ICD-10-CM guidelines this code should not to be used as a principal diagnosis code when a related definitive diagnosis has been established.

Specific Coding Applicable to Ascites

Non-specific codes like R18 require more digits to indicate the appropriate level of specificity. Consider using any of the following ICD-10-CM codes with a higher level of specificity when coding for ascites:

  • Use R18.0 for Malignant ascites - BILLABLE CODE

  • Use R18.8 for Other ascites - BILLABLE CODE

Clinical Information

  • Ascites

    accumulation or retention of free fluid within the peritoneal cavity.
  • Carcinoma, Ehrlich Tumor

    a transplantable, poorly differentiated malignant tumor which appeared originally as a spontaneous breast carcinoma in a mouse. it grows in both solid and ascitic forms.
  • Chylous Ascites

    presence of milky lymph (chyle) in the peritoneal cavity, with or without infection.
  • Mucin-4

    a transmembrane mucin that is found in a broad variety of epithelial tissue. mucin-4 may play a role in regulating cellular adhesion and in cell surface signaling from the erbb-2 receptor protein-tyrosine kinase. mucin-4 is a heterodimer of alpha and beta chains. the alpha and beta chains result from the proteolytic cleavage of a precursor protein.
  • Peritoneovenous Shunt

    an operation for the continuous emptying of ascitic fluid into the venous system. fluid removal is based on intraperitoneal and intrathoracic superior vena cava pressure differentials and is performed via a pressure-sensitive one-way valve connected to a tube traversing the subcutaneous tissue of the chest wall to the neck where it enters the internal jugular vein and terminates in the superior vena cava. it is used in the treatment of intractable ascites.
  • Pseudomyxoma Peritonei

    a peritoneal adenocarcinoma characterized by build-up of mucus in the peritoneal cavity. mucus secreting cells may attach to the peritoneal lining and continue to secrete mucus. the majority of cases represent tumor spread from a primary low-grade mucinous neoplasm of the appendix (nci thesaurus).
  • Receptor, ErbB-2

    a cell surface protein-tyrosine kinase receptor that is overexpressed in a variety of adenocarcinomas. it has extensive homology to and heterodimerizes with the egf receptor, the erbb-3 receptor, and the erbb-4 receptor. activation of the erbb-2 receptor occurs through heterodimer formation with a ligand-bound erbb receptor family member.

Tabular List of Diseases and Injuries

The following annotation back-references are applicable to this diagnosis code. The Tabular List of Diseases and Injuries is a list of ICD-10-CM codes, organized "head to toe" into chapters and sections with coding notes and guidance for inclusions, exclusions, descriptions and more.


This note appears immediately under a three character code title to further define, or give examples of, the content of the category.
  • fluid in peritoneal cavity

Type 1 Excludes

Type 1 Excludes
A type 1 excludes note is a pure excludes note. It means "NOT CODED HERE!" An Excludes1 note indicates that the code excluded should never be used at the same time as the code above the Excludes1 note. An Excludes1 is used when two conditions cannot occur together, such as a congenital form versus an acquired form of the same condition.
  • ascites in alcoholic cirrhosis K70.31
  • ascites in alcoholic hepatitis K70.11
  • ascites in toxic liver disease with chronic active hepatitis K71.51

Patient Education

Liver Diseases

Your liver is the largest organ inside your body. It helps your body digest food, store energy, and remove poisons.

There are many kinds of liver diseases:

  • Diseases caused by viruses, such as hepatitis A, hepatitis B, and hepatitis C
  • Diseases caused by drugs, poisons, or too much alcohol. Examples include fatty liver disease and cirrhosis.
  • Liver cancer
  • Inherited diseases, such as hemochromatosis and Wilson disease

Symptoms of liver disease can vary, but they often include swelling of the abdomen and legs, bruising easily, changes in the color of your stool and urine, and jaundice, or yellowing of the skin and eyes. Sometimes there are no symptoms. Tests such as imaging tests and liver function tests can check for liver damage and help to diagnose liver diseases.

[Learn More in MedlinePlus]

Code History

  • FY 2024 - No Change, effective from 10/1/2023 through 9/30/2024
  • FY 2023 - No Change, effective from 10/1/2022 through 9/30/2023
  • FY 2022 - No Change, effective from 10/1/2021 through 9/30/2022
  • FY 2021 - No Change, effective from 10/1/2020 through 9/30/2021
  • FY 2020 - No Change, effective from 10/1/2019 through 9/30/2020
  • FY 2019 - No Change, effective from 10/1/2018 through 9/30/2019
  • FY 2018 - No Change, effective from 10/1/2017 through 9/30/2018
  • FY 2017 - No Change, effective from 10/1/2016 through 9/30/2017
  • FY 2016 - New Code, effective from 10/1/2015 through 9/30/2016. This was the first year ICD-10-CM was implemented into the HIPAA code set.