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.