OC09.06: Update on the distribution of ovarian and deep endometriosis based on combination of advanced pelvic ultrasound and surgery

An up-to-date description of ovarian and deep endometriosis distribution is necessary as the diagnostic algorithm now includes ultrasound as a highly specific diagnostic test. The primary objective was to describe ovarian/deep endometriosis distribution based on the combination of ultrasound, surgery, and pathology. The secondary objective was to determine if a certain location at surgery had a higher correlation with histopathology-confirmed endometriosis. 145 consecutive patients underwent ultrasound and surgery by one of two gynecologists in a tertiary care centre between October 2020-January 2023. All endometriosis lesions were excised unless otherwise decided by the patient. Standard ultrasound/surgery reports were reviewed, and data extracted. Chi-Square Tests and Pearson's correlation coefficients were calculated to define the correlation between surgical diagnosis and pathology diagnosis for each anatomical location. When combining findings from preoperative ultrasound, surgery and pathology, the most frequent locations for deep disease were uterosacral ligaments (51.0%), ovaries (45.5%), torus uterinus (19.3%) and bowel (17.2%). Deep endometriosis was more common on the left versus right uterosacral ligament (42.7% vs. 34.5%) and on the left versus right ovary (33.8% vs. 26.9%). Amongst patients with ovarian endometriosis, 74.2% had deep endometriosis in at least one other site. There was a significant association between surgically identified lesions and pathology confirmation for all locations (Chi-Square Test, p < 0.05). The correlation was strong for all locations (Pearson's coefficient 0.70-0.90, p < 0.05). The addition of advanced pelvic ultrasound to the diagnostic approach of patients with deep endometriosis allows for a more accurate description of disease distribution, combining ultrasound, surgical and pathological findings. In our cohort, we describe the most common locations for deep endometriosis as the uterosacral ligaments followed by the ovaries and the torus uterinus.