Transvaginal ultrasonography (TVS) versus TVS with water-contrast in the rectum in the diagnosis of rectovaginal endometriosis infiltrating the bowel

Introduction: This study aims to determine the effectiveness of transvaginal ultrasonography (TVS) and TVS combined with water-contrast in the rectum(RWC-TVS) in the diagnosis of rectal infiltration in women with rectovaginal endometriosis. Materials and methods: This prospective study included 90 women with suspect of rectovaginal endometriosis who underwent operative laparoscopy. TVS and RWC-TVS were independently performed by different investigators. RWC-TVS was performed by injecting saline solution into the rectal lumen under ultrasonographic control through a 6 mm catheter. Presence of rectovaginal nodules, presence and degree of rectal infiltration, and largest diameter of bowel nodules were evaluated. Ultrasonographic results were compared to surgical and histological findings. Statistical analysis was performed by using the ANOVA on ranks (with the post hoc Dunn’s test), the McNemar’s test, and the Pearson’s correlation coefficient test. Results: Surgery and histology revealed that 69 patients (76.7%) had recto- vaginal endometriotic nodules; rectal infiltration was observed in 29 cases (32.2%). There was a trend for RWC-TVS to have higher accuracy than TVS in the diagnosis of rectovaginal endometriosis, but the difference between the two techniques was not statistically significant (TVS: sensitivity 92.8% and specificity 90.5%; RWC-TVS: sensitivity 97.1% and specificity 100.0%; P 1⁄4 0.074). TVS correctly identified the presence of rectal infiltration reaching at least the muscular layer in only 56.5% (13/23) of the cases; the sensitivity was 56.5%, the specificity 92.5%, the positive predictive value (PPV) 72.2%, the negative predictive value (NPV) 86.1%, and the accuracy of 83.3%. For RWC-TVS, the sensitivity was 95.7%, the specificity was 100.0%, the PPV 100.0%, the NPV 98.5%, and the accuracy 98.9%. The McNemar’s test showed that the accuracy of RWC-TVS and TVS were sig- nificantly different in determining the presence of endometriotic nodules infiltrating the rectal wall (P 1⁄4 0.001); combining the results of the two techniques did not increase the sensitivity of RWC-TVS. In women with rectal infiltration, RWC-TVS could not determine whether the mucosa was infil- trated; in patients with superficial lesions which did not reach the bowel muscularis, RWC-TVS could not determine whether the bowel serosa was infiltrated. RWC-TVS was more reliable in excluding the presence of endo- metriotic nodules infiltrating the rectal muscularis (negative likelihood ratio, 0.04) than TVS (negative likelihood ratio, 0.47). At histology the largest diameter of the endometriotic nodules ranged from 5 to 57mm (mean+SD, 24.7+12.5 mm), compared with 5 to 41 mm (20.2+8.9 mm) at TVS and 5 to 53 mm (22.0+11.40 mm) at RWC-TVS. Both TVS and RWC-TVS agreed with histology on the size of the lesions (P 1⁄4 0.01, r 1⁄4 0.912 and P 1⁄4 0.01, r 1⁄4 0.986, respectively). RWC-TVS determined higher intensity of pain on the VAS scale than TVS (4.0+1.9 and 2.0+1.1, respectively; P , 0.001). However, it was possible to perform RWC-TVS in all the patients, and only 23 women (25.6%) defined the intensity of pain “severe” (VAS score .5). For patients reporting higher intensity of pain at RWC-TVS, the median difference of pain intensity between the two exams was 1.8 (range, 0.1–6.0). RWC-TVS determined significantly higher intensity of pain in women with rectovaginal nodules infiltrating the rectum than in those with only rectovaginal endometriosis (P , 0.05) and in those without endometriosis (P , 0.05). Conclusions: RWC-TVS determines the presence of rectovaginal nodules infiltrating the rectal muscularis propria more accurately than TVS.