PGP 9.5 Positive Neural Fibers in Eutopic Endometrium of Women with Endometriosis: A Prospective Case-Control Study

Objective: TTo investigate the presence and number of PGP 9.5-positive endometrial neural fibers in women with sonographically confirmed endometrioma and pain symptoms, and to compare these findings with an asymptomatic control population.Material and Methods: In this prospective case-control study, 59 women aged 18-49 years were divided into 2 groups (31 endometriosis, 28 controls).The endometriosis group consisted of women with ultrasoundconfirmed endometrioma.Controls had normal ultrasonography and underwent endometrial biopsy for abnormal uterine bleeding without pelvic pain, dysmenorrhea, dyspareunia, infertility, or clinical suspicion of endometriosis.Pain severity was graded using the Biberoglu-Behrman scale.Pipelle was used to sample the eutopic endometrium.Specimens were stained for PGP 9.5 using an automated immunohistochemical platform.A single blinded gynecologic pathologist evaluated neural fibers.Appropriate parametric and non-parametric tests were applied, and p<0.05 was considered significant.Results: Mean age, age at menarche, and parity distributions were comparable, whereas median gravidity was lower in the endometriosis group (p=0.005).Dysmenorrhea, dyspareunia, and chronic pelvic pain were substantially more frequent and severe among endometriosis patients (all p<0.001).PGP 9.5 positive neural fibers were detected in 2/31 (6.5%) cases and 1/28 (3.6%) controls, with no significant difference in detection rates (p=0.599).Conclusion: In hormone-naive women sampled in the mid-proliferative phase, PGP 9.5 positive endometrial neural fibers were uncommon and did not discriminate endometriosis-associated pain from asymptomatic controls.Larger laparoscopically validated studies using standardized quantification are needed to clarify eutopic innervation and any biomarker role in pain phenotypes.