Chylous ascites is a milky-appearing peritoneal fluid that is rich in triglycerides. It is due to the presence of thoracic or intestinal lymph in the abdominal cavity .
Chylous ascites is an uncommon finding with a reported incidence of approximately 1 per 20,000 admissions at a large university-based hospital over a two-decade period . Although there have been no recent large epidemiologic studies, it is generally believed that the incidence has increased due to the longer survival of patients with cancer and more aggressive abdominal and cardiothoracic interventions.
Pathophysiology — Chylous ascites develops when there is a disruption of the lymphatic system, which occurs due to traumatic injury or obstruction (from benign or malignant causes). Three underlying mechanisms have been proposed :
●Obstruction of the lymph flow due to malignancy, causing leakage from dilated subserosal lymphatics into the peritoneal cavity. The effects of a continuous elevated pressure of the intestinal lymphatic system may lead to collagen deposition of the basement membrane of lymphatics, further impairing the absorptive capacity of the intestinal mucosa. This can ultimately lead to the development of a protein-losing enteropathy with chronic diarrhea (steatorrhea), malabsorption, and malnutrition. (See "Protein-losing gastroenteropathy".)
●Exudation of lymph through the walls of dilated retroperitoneal vessels lacking valves, which leak fluid through a fistula into the peritoneal cavity (ie, congenital lymphangiectasia).