Endometriosis most commonly affects the pelvic peritoneum close to the ovaries, including the uterosacral ligaments, the ovarian fossa peritoneum, and the perito- neum of the cul-de-sac. The increased diagnosis of endometriosis at laparoscopy can be explained by the increased experience and ability of the surgeon to detect such subtle lesions. The greatest change has been in the case of “subtle” lesions, which increased from 15% in 1986 to 65% in 1988. The diagnosis of peritoneal endometriosis at the time of laparoscopy is often made by the observation of typically puckered black or bluish lesions. There are, in addition, numerous subtle appearances of peritoneal endometriosis. These lesions, frequently nonpigmented, were diagnosed as endometriosis following confirmation by biopsy by Jansen and Russell in 1986.
Donnez, J., Nisolle, M., & Casanas-Roux, F. (1994). Peritoneal endometriosis: two-dimensional and three-dimensional evaluation of typical and subtle lesions. Annals / New York Academy of Sciences, 734, 342-351. https://doi.org/10.1111/j.1749-6632.1994.tb21764.x (Original work published 1994)