OP19.01: Introital three‐dimensional ultrasonography in the diagnosis of endometriosis of the rectovaginal septum: interobserver variability

The purpose of this study was to evaluate interobserver agreement in the diagnosis of deep endometriosis of the rectovaginal septum using introital three-dimensional ultrasonography (3D-US). Two experienced observers (Observers A and B) performed a retrospective review of 3D-US stored volumes from a sample of 84 consecutive patients with a clinical suspicious of endometriosis. Each observer independently, and blinded to each other, evaluated the presence or the absence of involvement of the rectovaginal septum. When no lesion was seen, observers were asked to judge if the acquisition of the volume was defective, or if no lesion on the rectovaginal septum was evident; defective acquisition cases were discarded, a total number of 83 cases were evaluated. In order to calculate the performance of the introital 3D US, seven discordant cases were reviewed by a third observer. Interobserver agreement was assessed by calculating kappa index (κ), and Sensitivity, Specificity, PPV and NPV by the three observers were also determined. Interobserver agreement was 0.816 (95% CI [0.69–0.93]) (representing a very good agreement). Sensitivity was 74.1%, Specificity 85.5%, PPV 71.4% and NPV 87%. Our results show that introital 3D US for diagnosis of deep endometriosis of the rectovaginal septum is reproducible with very good interobserver agreement.