In the pilot study, 15 of 20 patients examined were diagnosed with endometriosis on histology. All 15 patients were detected with NBI and white light. Four patients were diagnosed by lesions that were detected only with NBI. Based on these data, the estimated sensitivities of white light and NBI are 73% and 100% respectively. Given these sensitivities and the small total sample size, 95% confidence intervals are wide (48%-90% white light and 80%-100% NBI). At the lesion level, pilot data have shown an average of 2 lesions seen under white light compared to an average of 3 lesions using NBI. Using a common standard deviation of 1, the current sample size has at least 90% power to detect an average difference of at least one additional lesion.