The use of intra‐operative saline sonovaginography to define the rectovaginal septum in women with suspected rectovaginal endometriosis: a pilot study

Objectives: The aim of this study was to perform saline sonovaginography (SVG) in women with suspected rectovaginal endometriosis (RVE) in order to establish the thickness of the rectovaginal septum (RVS) in this population and to predict the presence or absence of RVE. Methods: Prospective observational pilot study. Women undergoing laparoscopy for possible endometriosis on the basis of history or clinical examination were offered to participate in the study. All women underwent saline SVG during general anesthesia just prior to their laparoscopy. RVS nodules were visualised as hypoechoic lesions of various shapes. The sonologist predicted whether or not a nodule was present in the retrocervical area or in the RVS. The thickness of the posterior vaginal wall ± RVS was then taken at three points in the mid-sagittal plane: at the posterior fornix (retrocervical area), at the middle third of the vagina (upper RVS) and just above the perineal body (lower RVS). The diagnosis of RVE was established using the gold standards of laparoscopy and histological confirmation. The RVS thickness was then compared between women with RVE and the absence of RVE. Results: Twenty-three women were enrolled in the study. Mean age was 38 years (33-44 years). A history of endometriosis was present in 72.7% (8/11). RVE was confirmed in 17.4% (4/23). Visualisation of a hypoechoic nodule at saline SVG demonstrated sensitivity and specificity of 75% and 95%, respectively. All rectovaginal nodules were located in the retrocervical region. Mean diameter (SD) of RVE nodules was 27.3 (± 9.4) mm. Mean thickness of vaginal wall ± RVS at the posterior fornix, at the middle third of the vagina and just above the perineal body was 5.1, 1.4 and 4.0 mm, respectively. These measurements were not significantly different in the presence of a rectovaginal nodule. Conclusions: Using saline SVG, we have established the mean RVS thickness in a small group of women with suspected RVE. Although the numbers are small, there was no correlation between RVS thickness and presence of RVE. The visualisation of hypoechoic lesions at saline SVG seems to be the best ultrasonographic predictor for RVE. SVG is a valuable pre-operative tool for the assessment of RVS and for the prediction of RVE, which allows for the mapping and planning of advanced endometriosis surgery.