Diagnostic yield: The calculations for sample size were based on information obtained from a pilot study that examined patients using white light followed by NBI during diagnostic laparoscopy. In that study, 4 additional patients were diagnosed with endometriosis with the addition of NBI to white light examination for an absolute improvement of 27% (4/15 patients with endometriosis were found with NBI examination only) (Barrueto and Audlin, 2008). Using these data, sample size calculations were conducted using nQuery 6.01 (Elashoff, 2005) for a two group chi-square test with unequal Ns (3:1 ratio). A two group chi-square test with a 0.05 two-sided significance level will have 90% power to detect the difference between a Group 1 (white light/white light) diagnostic yield of 0.79 and a Group 2 (white light/NBI) diagnostic yield of 0.99 when the sample sizes in each group are 34 and 101, respectively (a total sample size of 135).