OC19.01: *An ultrasound study of the prevalence of endometriosis in pregnancy

The aim of this study was to assess the prevalence and morphological appearances of ovarian endometriomas and deep pelvic endometriomas using pelvic ultrasound examination in women attending for early pregnancy care. This was a prospective observation cohort study that was carried out within a dedicated early pregnancy unit. We included a total of 1341 consecutive women who attended for an early pregnancy assessment for reassurance or due to suspected early pregnancy complications. All of these women underwent a transvaginal ultrasound scan to assess the location and viability of their pregnancies. A detailed examination of the pelvic organs was also carried out, to detect the presence of endometriosis and other gynecological abnormalities. Data analysis was performed using logistic regression and multivariate analysis. We found that the prevalence of deep endometriosis and ovarian endometriomas in women attending our early pregnancy unit was 4.9% (95% CI 3.8 – 6.2). In 33/66 (50%, 95% CI 37.9 – 62.1) women with endometriosis, this was a novel diagnosis made for the first time during their early pregnancy scan. On multivariate analysis the presence of endometriosis was strongly associated with East Asian ethnicity, a history of subfertility, congenital uterine anomalies and uterine fibroids. Morphological changes typical of decidualisation were seen in 11/33 (33.3%, 95% CI 17.2 – 49.4)) endometriomas and 18/57 (31.6%, CI 19.5 – 43.7) deep endometriotic nodules. Ovarian endometrioma and deep endometriotic nodules were present in a significant proportion of women attending for early pregnancy assessment. The true prevalence of endometriosis is likely to differ significantly among diverse populations, depending on their characteristics. Ultrasound is a useful tool for the detection of endometriosis in early pregnancy and to identify women who may benefit from specialist antenatal care.