Does transvaginal ultrasonography combined with water-contrast in the rectum aid in the diagnosis of rectovaginal endometriosis infiltrating the bowel?

BACKGROUND: The aim of this study was to determine whether adding water-contrast in the rectum during transvaginal ultrasonography (RWC-TVS) improves the diagnosis of rectal infiltration in women with rectovaginal endometriosis. METHODS: This prospective study included 90 women, with suspect 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 the largest diameter of the bowel nodules were evaluated. Ultrasonographic results were compared to surgical and histological findings. RESULTS: Although RWC-TVS had higher accuracy than TVS in diagnosing rectovaginal endometriosis, the difference between the two techniques was not statistically significant. RWC-TVS was significantly more accurate than TVS in determining the presence of endometriotic infiltration reaching at least the muscular layer of the rectal wall. The sensitivity of RWC-TVS in identifying rectal lesions was 97%, the specificity 100%, the positive predictive value 100% and the negative predictive value 91.3%. RWC-TVS caused a higher intensity of pain than TVS. CONCLUSIONS: RWC-TVS determines the presence of rectovaginal nodules infiltrating the rectal muscularis propria more accurately than TVS; RWC-TVS could be used when TVS cannot exclude the presence of rectal infiltration.