Value of endorectal ultrasonography for diagnosing rectovaginal septal endometriosis infiltrating the rectum

Background and Study Aims: Rectovaginal septal endometriosis (RVSE) can pose serious therapeutic problems when there is infiltration of the rectal septum (which occurs in approximately half of the cases). The aim of this study was to assess the value of endoscopic ultrasonography in diagnosing rectal wall involvement by pelvic endometriosis. Patients and Methods: A prospective study was carried out from May 1998 to March 2003 at a single hospital center. The 30 patients included in the study presented with suspected RVSE and underwent systematic anorectal endoscopic ultrasonographic exploration prior to the surgical intervention. The endoscopic ultrasonography was carried out under general anesthesia with a 7.5-MHz miniprobe equipped with a distal balloon. Results: The anorectal endoscopic ultrasonographic examination (EUS) showed the presence of endometriosis in the rectovaginal septum in 26 patients (88%), in the uterosacral ligaments in 10 patients (33%), and in the ovaries. in two patients (6 %). At EUS, the nodules were infiltrating the rectal wall in 17 patients (56%). The surgical exploration demonstrated endometriosis in the rectovaginal septum in 26 cases, the uterosacral ligaments in 22 cases, and the ovaries in 16 cases. The rectal wall was completely infiltrated in 12 cases and only partly in four cases, and intestinal tract resection was required in 10 cases. The sensitivity, specificity, and positive and negative predictive value of anorectal endoscopic ultrasonography as a means of diagnosing endometriosis of the rectovaginal septum and infiltration of the rectal wall were found to be 96%, 100%, 100% and 83%, and 92%, 66%, 64% and 92%, respectively; and the diagnostic accuracy was at 96% and 80%, respectively. The sensitivity for detecting nodules in the uterosacral ligaments or in the ovaries was 42% and 14%, respectively, leading to diagnostic accuracy rates of 56% and 53%. Conclusions: In terms of its sensitivity and its negative predictive value, anorectal endoscopic ultrasonography is a very effective means of detecting endometriosis of the rectovaginal septum and assessing possible infiltration of the rectal wall. However, this method is not as accurate for nodules located far from the EUS probe, as is the case with the uterosacral ligaments and ovaries.