P18.02: Prevalence of negative 'sliding sign' in low‐risk population: a feasibility study

The prevalence of a ‘negative sliding sign’ in the low risk population is not known. Our aim is to determine the prevalence of a ‘negative sliding sign’ in low-risk women. An ongoing prospective study. Women attending the gynecology service at Nepean Hospital who were deemed low-risk for rectouterine adhesions were included in the study (i.e. nil previous or current history of endometriosis or PID, nil chronic pelvic pain, nil history of infertility or fertility treatment, nil previous pelvic surgery). Power calculation has predetermined a study size of n=303 women is required. Each woman was assessed for the presence of ‘sliding sign’ on transvaginal ultrasound at the both the retro-cervix and posterior uterine fundus. When the ‘sliding sign’ is considered positive in both of these anatomical regions (RC and PUF), the POD is recorded as ‘not obliterated’. If either of these anatomical regions demonstrates that the anterior rectal wall or rectosigmoid does not glide smoothly over the RC or PUF, respectively, then the ‘sliding sign’ is considered negative, and the POD is recorded as ‘obliterated’. Each woman was also assessed for ovarian mobility or presence/absence of an ovarian endometrioma. 613 women were recruited. 236 were excluded due to the presence of previous PID and/or endometriosis, 4 were excluded from this study as they were concerned about the safety of TVS in early pregnancy, 124 due to previous pelvic surgery, 21 due to previous fertility treatment/subfertility and 22 as they were beyond 12 weeks gestation. We noted that the real-time ultrasound based ‘sliding sign’ was positive in all 206 women and therefore the POD was recorded as non-obliterated. The ovaries were noted to be mobile in all cases as well. Although this is an ongoing study, the preliminary results suggest that the prevalence of POD obliteration on ultrasound evaluation in the low-risk population is negligible.