Lesions will be recorded according as falling within three categories: visible white light-detected only; NBI-detected only; or both NBI- and visible white light-detected. Pathology will be performed at each center following a standardized protocol for the diagnosis of endometriosis. Pathologists at each institution will be masked to the method of examination used to identify the specimen. All discordant lesions (visualized under only one imaging modality), a random 10% sample of specimens and a random 10% of images from each center will be re-reviewed by a central independent reviewer at the coordinating center.