VP62.11: 3D rectal water‐contrast transvaginal ultrasonography versus CT colonography for estimating bowel stenosis due to rectosigmoid endometriosis

The objective of this study was to evaluate the performance of 3D rendering during rectal water contrast transvaginal ultrasonography (RWC-TVS) for estimating the bowel lumen stenosis caused by rectosigmoid endometriosis in comparison to computed tomography (CT) colonography (CTC). This prospective study included patients with suspicion of rectosigmoid endometriosis who underwent both RWC-TVS and CTC and subsequently were surgically treated by laparoscopic segmental resection. CTC was performed within 3 months from RWC-TVS by a physician blinded to the ultrasonographic findings. The percentage of stenosis was evaluated during RWC-TVS in the transversal plane of bowel lumen reconstructed by 3D rendering and during CTC in sagittal reconstruction. The percentage of stenosis was estimated by subtracting the mean area of the endometriotic nodule from the mean area of healthy bowel lumen calculated 3 cm above and below the nodule. The findings of imaging were compared with surgical and histological results. Out of 64 women included, 35 (54.7%; 95 CI 33.0-58.0%) had rectosigmoid nodules and underwent segmental colorectal resection; in these patients, the mean ( ± SD) length of the resected bowel specimen was 11.5 ± 1.9 cm; the mean largest diameter and volume of the largest endometriotic nodule were 29.4 ( ± 9.4) mm and 5.3 ( ± 4.0) cm3, respectively. At the pathological examination, the degree of bowel lumen stenosis was 55.8 ± 24.4 %. CTC and RWC-TVS similarly estimated the degree of the stenosis (p = 0.176). The mean difference in the estimation of lumen stenosis was 13.8 ± 13.2% for RWC-TVS and 9.9 ± 12.2% for CTC in comparison to surgery. RWC-TVS was less accurate than CTC in determining lumen stenosis due to endometriotic nodules located in the sigmoid colon (p = 0.04). RWC-TVS with 3D rendering estimates similarly to CTC the bowel stenosis due to rectosigmoid endometriosis. However, CTC is more accurate in determining the stenosis of upper rectosigmoid nodules.