Malignant ascites

This code signifies the presence of fluid accumulation in the peritoneal cavity that is directly caused by a malignant process. This typically indicates metastatic disease to the peritoneum or advanced primary intra-abdominal malignancy. The fluid often contains malignant cells, leading to abdominal distension and discomfort.

Apply this code when documentation explicitly states "malignant ascites" or "ascites due to malignancy." This diagnosis is frequently seen in patients with advanced cancers such as ovarian, colorectal, pancreatic, or gastric carcinoma. Pathological confirmation of malignant cells in the ascitic fluid or clear clinical evidence linking the ascites to a known malignancy supports its use.

• Always code the underlying primary malignancy first, followed by this code as a secondary diagnosis.
• Do not use this code for ascites of non-malignant origin (e.g., liver cirrhosis, heart failure); use codes from the K70-K76 or I50 series instead.
• Ensure documentation clearly links the ascites to a malignant cause; "ascites" alone is insufficient.