Hidden Burden of Fallopian Tube Endometriosis: Prevalence and Associations with Pelvic Pathology

<b>Background/Objectives:</b> Fallopian tube endometriosis is frequently underreported due to its nonspecific presentation, limitations in imaging detection, and the fact that histologic diagnosis often requires the submission of the entire fallopian tube for microscopic analysis, which is not routinely performed. This study investigates the prevalence of fallopian tube endometriosis on histologic evaluation in patients undergoing laparoscopic salpingectomy for benign gynecologic conditions, and evaluates its association with intraoperative findings such as endometriomas, hydrosalpinx, and peri-tubal adhesions. <b>Methods:</b> A prospective cohort study was conducted from September 2021 to December 2024 at NYU Grossman Long Island School of Medicine, including 80 women ages 18-65 years undergoing unilateral or bilateral salpingectomy. Fallopian tubes were entirely submitted for histologic examination and were evaluated in cross-sections for presence of endometriosis. The association between the presence of fallopian tube endometriosis, the stage of endometriosis, the presence of endometriomas, hydrosalpinx, and tubal adhesions was analyzed, with significance defined as <i>p</i> < 0.05. <b>Results:</b> 47 women were found to have biopsy-proven pelvic endometriosis (58.75%). The prevalence of fallopian tube endometriosis was 42.50% (34/80) in the total study population and 72.34% (34/47) among patients with pelvic endometriosis. The most commonly involved layer was the serosa (75.5%), followed by the muscularis (46.9%) and mucosa (18.4%). Fallopian tube endometriosis was significantly associated with endometriomas (<i>p</i> < 0.0001), hydrosalpinx (<i>p</i> < 0.0001), and tubal adhesions (<i>p</i> < 0.0001). It was also strongly correlated with disease severity, with 92.9% of patients with stage 4 endometriosis exhibiting tubal involvement. <b>Conclusions:</b> Fallopian tube endometriosis is more prevalent than previously recognized and shows a strong association with advanced-stage endometriosis, endometriomas, hydrosalpinx, and tubal adhesions.