Quantitative studies of ascitic fluid circulation with tritium-labeled water

Six patients with ascites have been studied, four with portal cirrhosis and two with peritoneal carcinomatosis. It has been shown in these patients, using tritium-labeled water, that the water content of ascitic fluid enters and leaves the peritoneal cavity at a very rapid rate, approximating 40 to 80 per cent per hour. Ascitic fluid, then, is a rapidly circulating medium rather than a segregated reservoir. The peritoneal surfaces of both normal and diseased individuals are capable of reabsorbing large volumes of fluid. Not until the rate of inflow exceeds this maximum reabsorptive capacity, here designated as the ascites threshold, does ascites result. Using this principle the presence or absence of ascites in a variety of apparently contradictory conditions becomes more easily understandable.