There are multiple physiological differences between males and females; however, considerable evidence implicates estrogenic sex hormones as critical factors in sex-dependent differences in pain (see review by Fillingim and Ness, 2000). It is possible that estrogens alter inflammatory mediator profiles in the gallbladder, which subsequently increase sensitization of visceral neurons innervating the gallbladder, resulting in increased pain in females. The first portion of this study will extend the association of patient sex with clinical outcomes to determine whether circulating and/or local estrogen levels correlate with differences in peri-operative morbidity, including intra-operative complications, conversion to open cholecystectomy, postoperative pain, inadequate wound healing, intra-abdominal infection, disability and mortality.