Prevalence of deep and ovarian endometriosis in early pregnancy: ultrasound diagnostic study

To assess the prevalence and morphological appearance of deep endometriosis and ovarian endometrioma using pelvic ultrasound examination in women attending for an early pregnancy assessment.

This was a prospective observational study set within a dedicated early pregnancy unit. The study included 1341 consecutive women who attended for an early pregnancy assessment for reassurance or because of suspected early pregnancy complications. All women underwent a transvaginal scan to assess the location and viability of their pregnancy. In addition, a detailed examination of pelvic organs was carried out to detect the presence of endometriosis and other gynecological abnormalities. Data analysis was performed using logistic regression and multivariable analysis.

The prevalence of deep endometriosis and/or ovarian endometrioma in women attending our early pregnancy unit was 4.9% (95% CI, 3.8-6.2%). In 33/66 (50.0% (95% CI, 37.9-62.1%)) women with endometriosis, this was a new diagnosis that was made during their early pregnancy scan. On multivariable analysis, the presence of endometriosis was strongly associated with a history of subfertility (odds ratio (OR), 3.15 (95% CI, 1.63-6.07)) and presence of a congenital uterine anomaly (OR, 5.69 (95% CI, 2.17-14.9)) and uterine fibroids (OR, 2.37 (95% CI, 1.31-4.28)). Morphological changes typical of decidualization were seen in 11/33 (33.3% (95% CI, 17.2-49.4%)) women with ovarian endometrioma and 18/57 (31.6% (95% CI, 19.5-43.7%)) women with deep endometriotic nodules.

Deep endometriosis and ovarian endometrioma were present in a significant proportion of women attending for early pregnancy assessment. The prevalence varied depending on a history of subfertility, and therefore is likely to differ significantly among populations, depending on their characteristics. Ultrasound is a useful tool for the detection of endometriosis in early pregnancy and the identification of women who may benefit from specialist antenatal care. © 2021 International Society of Ultrasound in Obstetrics and Gynecology.