Evaluation of Ascites by Ultrasound

Ultrasound was used to determine the presence of free intraperitoneal fluid. Base-line values were obtained by introducing known amounts of fluid into the peritoneal cavities of cadavers and obtaining readings in multiple positions, the right lateral decubitus and hand-knee positions being the most sensitive. As little as 100 ml of fluid could be detected. Ultrasonic patterns changed with repositioning of the patient, confirming the presence of free intraperitoneal fluid rather than loculated collections.