Transvaginal Ultrasonographic Visualization of Endometriosis as a Unified Peritoneal Thickening.

Background and Objectives: This study characterized the peritoneal surface of the posterior cervix and vaginal fornix. Transvaginal ultrasonography (TVUS) was performed during laparoscopic surgery to visualize structures beyond the muscular and epithelial layers and to evaluate their association with endometriosis. Methods: Pelvic pain was assessed using a 10 cm visual analog scale. During laparoscopic surgery, saline solution was infused into the pelvic cavity, after which sagittal TVUS images were obtained from the vaginal wall to the peritoneal surface, covering the region from the midline posterior fornix to the bilateral uterosacral ligaments. Fibrotic lesions within the trapezoidal area formed by the posterior cervix, posterior fornix, and uterosacral ligaments were dissected and excised for histopathological analysis. Vaginoperitoneal thickness (VPT)-the distance from the vaginal wall to the peritoneal surface-was measured before and after lesion removal. Results: TVUS revealed a thickened structure on the peritoneal surface of the posterior vaginal fornix. Uniform granular hyperechogenicity was observed in 65.4% of cases, while partial hypoechoic areas were noted in 34.6%. The structure appeared as a unified lesion extending from the midline to the lateral uterosacral ligament region. Histological examination confirmed endometrial glands and/or stroma in 60.4% of excised lesions and fibrosis in 31.7%. Postoperative VPT was significantly reduced compared with preoperative measurements, with improvement in pain scores observed. Conclusions: TVUS visualized a continuous endometriotic lesion extending from the posterior cervix and fornix to the bilateral uterosacral ligaments. VPT measurement may provide a measurable parameter for describing peritoneal involvement in endometriosis.