Ascitic Fluid Cytology

Function

Ascitic Fluid Cytology involves the microscopic examination of fluid collected from the peritoneal cavity (the space between the abdominal lining and the organs). The primary goal is to identify abnormal cells, particularly malignant (cancerous) cells, which may shed into the fluid from nearby organs. This process involves centrifuging the fluid to concentrate the cellular material, which is then stained and reviewed by a pathologist.

Why it is Ordered

This test is a standard part of a 'paracentesis' workup when the cause of fluid buildup (ascites) is unknown. It is specifically ordered to:

• Detect Malignancy: To confirm if the ascites is 'malignant ascites,' often caused by peritoneal carcinomatosis.
• Staging: To help stage certain cancers, such as ovarian or gastric cancer.
• Differential Diagnosis: To distinguish between portal hypertension (cirrhosis) and inflammatory or neoplastic causes of fluid accumulation.

Associated Conditions

The presence of malignant cells in ascitic fluid is most commonly associated with:

• Ovarian Cancer: One of the most frequent causes of malignant ascites in women.
• Gastrointestinal Malignancies: Including stomach, pancreatic, and colorectal cancers.
• Mesothelioma: A rare cancer of the lining of the abdomen often linked to asbestos exposure.
• Lymphoma: Which can cause a milky (chylous) ascites containing lymphocytes. While the test is highly specific (meaning a positive result is almost certainly cancer), it has moderate sensitivity, meaning some cancers may not shed enough cells to be detected in a single sample.