Resumen:
Objectives: The aim of this study was to evaluate the use of ultrasound (US) soft markers as a first-line imaging tool to raise suspicion of rectosigmoid (RS) involvement in women suspected of having deep endometriosis. Methods: We included in this prospective observational study all patients with clinical suspicion of deep endometriosis who underwent diagnostic transvaginal US evaluation at our unit from January 2016 to February 2017. Several US soft markers were evaluated for prediction of RS involvement (presence of US signs of uterine adenomyosis, presence of an endometrioma, adhesion of the ovary to the uterus (reduced ovarian mobility), presence of 'kissing ovaries' (KO) and absence of the 'sliding sign'), using as the gold standard expert US examination for the presence of RS endometriosis. Results: Included were 333 patients with clinical suspicion of deep endometriosis. Of these, 106 had an US diagnosis of RS endometriosis by an expert. The only significant variables found in the prediction model were absence of the sliding sign (odds ratio (OR), 13.95; 95% CI, 7.7-25.3), presence of KO (OR, 22.5; 95% CI, 4.1-124.0) and the interaction between these two variables (OR, 0.03; 95% CI, 0.004-0.28). Regarding their interaction, RS endometriosis was present when KO was absent and the sliding sign was present in 10% (19/190) of cases, when both KO and the sliding sign were present in 71.4% (5/7) of cases, when both KO and the sliding sign were absent in 60.8% (76/125) of cases and when KO was present and the sliding sign was absent in 54.5% (6/11) of cases. Thus, when the sliding sign was absent and/or KO was present, transvaginal US showed a specificity of 75% (95% CI, 69-80%) and a sensitivity of 82% (95% CI, 73-88%). Conclusions: US findings of absence of the sliding sign and/or presence of KO in patients with clinical suspicion of endometriosis should raise suspicion of RS involvement and indicate referral for expert US examination, with a low rate of false-negative diagnosis.