VP62.24: Is bowel preparation necessary before three‐dimensional rectal water‐contrast transvaginal ultrasonography for diagnosing the presence of rectosigmoid endometriosis?

Three-dimensional (3D) reconstructions may be employed during transvaginal rectal water-contrast transvaginal ultrasonography (RWC-TVS) to diagnose rectosigmoid endometriosis. This study aims to evaluate the influence of bowel preparation (BP) on the diagnostic performance of 3D-RWC-TVS in patients with suspicion of rectosigmoid endometriosis. This prospective comparative study enrolled women referred to our institution for the suspicion of rectosigmoid endometriosis. Patients underwent 3D-RWC-TVS with and without BP within an interval of 1–8 weeks. BP consisted in a low-residue diet given in the two days before the examination and a rectal enema administered a few hours before the procedure. During the two ultrasonographic exams, acquisitions of images by 3D rendering were made in the sagittal and coronal planes. After being stored data file, the two exams were separately offline analysed by two experienced sonographers, blinded to the results of bidimensional RWC-TVS. The imaging findings were compared with surgical and histological results. At surgery, 34 out of 57 patients (59.6%) had rectosigmoid endometriosis. 3D-RWC-TVS with previous BP had a significantly higher performance for diagnosing the presence of rectosigmoid endometriosis than 3D-RWC-TVS without BP (ROC-AUC 0.88 vs 0.72; p = 0.035). The sensitivity, specificity, positive predictive value, negative predictive value of 3D-RWC-TVS with and without BP were respectively 85.3% (95% CI, 68.9–95.1%), 91.3% (72.0–98.9%), 93.6% (79.3–98.2%), 80.8% (64.9–90.5%) and 70.6% (52.5–84.9%), 73.9% (51.4–89.8%), 80.0% (66.0–89.1%), 63.0% (48.09–75.1%); 3D-RWC-TVS with BP described more accurately the largest diameter and volume of rectosigmoid nodules (p < 0.001 and p < 0.001). Both exams did not differently detect the presence of multifocal disease (p = 0.69). This study demonstrates that BP is necessary before 3D-RWC-TVS as the presence of feces may negatively impact the visualisation of endometriotic nodules.