48 patients scheduled for an arthroscopic shoulder procedure were randomized to receive intra-articular irrigation with normal saline using an automated pump system or a gravity flow system. The primary outcome of interest was soft tissue fluid retention, as measured by weight gain post-operation. Secondary outcomes of interest included the increase in deltoid diameter and pain scores on a Visual Analog Scale (VAS). Results found significantly greater weight gain, weight gain per hour, weight gain per liter, deltoid diameter increase and VAS pain at 1 hour in the automated pump system group compared to the gravity flow system group.