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v1.0.0
ICD-10 Guide
ICD-10 CodesR18.0

R18.0

Malignant ascites

BILLABLE STATUSYes
IMPLEMENTATION DATEOctober 1, 2015
LAST UPDATED09/11/2025

Code Description

ICD-10 R18.0 is a billable code used to indicate a diagnosis of malignant ascites.

Key Diagnostic Point:

Malignant ascites refers to the accumulation of fluid in the peritoneal cavity due to malignancy. This condition is often associated with advanced stages of cancer, particularly cancers of the ovary, liver, pancreas, and gastrointestinal tract. Patients may present with abdominal distension, discomfort, and weight gain due to fluid retention. Physical examination may reveal a tense, distended abdomen with shifting dullness on percussion. Laboratory findings may include elevated protein levels in the ascitic fluid and cytological analysis may reveal malignant cells. The presence of malignant ascites indicates a poor prognosis and often requires palliative management, including paracentesis for symptomatic relief. Accurate diagnosis and coding are crucial for appropriate treatment and management of the underlying malignancy.

Code Complexity Analysis

Complexity Rating: Medium

Medium Complexity

Complexity Factors

  • Requires understanding of underlying malignancies
  • Differentiation from non-malignant ascites
  • Need for accurate documentation of clinical findings
  • Potential for multiple co-existing conditions

Audit Risk Factors

  • Inadequate documentation of malignancy type
  • Failure to document the clinical significance of ascites
  • Misclassification of ascites as non-malignant
  • Lack of supporting lab results or imaging studies

Specialty Focus

Medical Specialties

Internal Medicine

Documentation Requirements

Detailed history of malignancy, physical exam findings, and lab results.

Common Clinical Scenarios

Patients with known cancer presenting with abdominal distension.

Billing Considerations

Ensure documentation reflects the relationship between the malignancy and ascites.

Emergency Medicine

Documentation Requirements

Acute assessment of abdominal symptoms, imaging results, and immediate management plans.

Common Clinical Scenarios

Patients presenting with acute abdominal pain and known malignancy.

Billing Considerations

Document acute changes in condition and any interventions performed.

Coding Guidelines

Inclusion Criteria

Use R18.0 When
  • Follow official ICD
  • CM guidelines for coding malignant ascites, ensuring that the underlying malignancy is documented and coded appropriately

Exclusion Criteria

Do NOT use R18.0 When
No specific exclusions found.

Related CPT Codes

49083CPT Code

Paracentesis, abdominal cavity

Clinical Scenario

Used for therapeutic drainage of malignant ascites.

Documentation Requirements

Document indication for procedure, fluid analysis results, and patient response.

Specialty Considerations

Ensure that the procedure is linked to the diagnosis of malignant ascites.

ICD-10 Impact

Diagnostic & Documentation Impact

Enhanced Specificity

ICD-10 Improvements

The transition to ICD-10 has allowed for more specific coding of conditions like malignant ascites, improving the accuracy of data collection and reimbursement processes.

ICD-9 vs ICD-10

The transition to ICD-10 has allowed for more specific coding of conditions like malignant ascites, improving the accuracy of data collection and reimbursement processes.

Reimbursement & Billing Impact

reimbursement processes.

Resources

Clinical References

  • •
    ICD-10-CM Official Guidelines for Coding and Reporting

Coding & Billing References

  • •
    ICD-10-CM Official Guidelines for Coding and Reporting

Frequently Asked Questions

What is the primary cause of malignant ascites?

Malignant ascites is primarily caused by the spread of cancer cells to the peritoneal cavity, leading to fluid accumulation due to increased vascular permeability and lymphatic obstruction.