- Chylous ascites is the accumulation of milky, triglyceride-rich lymphatic fluid in the peritoneal cavity.
- The most common underlying cause is lymphatic obstruction or disruption, which leads to leakage of lymph from the dilated lymphatics into the abdomen.
- This obstruction may arise from malignancy, trauma, infection, or congenital abnormalities.
- Other causes like portal venous thrombosis, bacterial peritonitis, or pancreatic pseudocyst do not characteristically cause lymphatic leakage of chyle.
- Therefore, lymphatic obstruction is the primary pathological mechanism leading to chylous ascites.

Reference: Davidson’s Principles and Practice of Medicine, 23rd Edition, Chapter: Diseases of the Liver and Biliary System, Page 682.