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

Ultrasound Obstet Gynecol. 2022 Jan;59(1):107-113. doi: 10.1002/uog.24756.


Objective: 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.

Methods: 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.

Results: 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.

Conclusions: 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.

Keywords: decidualization; endometriosis; pregnancy; prevalence; ultrasonography.

Publication types

  • Observational Study

MeSH terms

  • Adult
  • Endometriosis / diagnostic imaging
  • Endometriosis / epidemiology*
  • Endometriosis / pathology
  • Female
  • Humans
  • Infertility, Female / complications
  • Infertility, Female / epidemiology
  • Odds Ratio
  • Ovarian Diseases / diagnostic imaging
  • Ovarian Diseases / epidemiology*
  • Ovarian Diseases / pathology
  • Pregnancy
  • Pregnancy Complications / diagnostic imaging
  • Pregnancy Complications / epidemiology*
  • Pregnancy Complications / pathology
  • Prevalence
  • Prospective Studies
  • Ultrasonography, Prenatal*
  • Urogenital Abnormalities / diagnostic imaging
  • Urogenital Abnormalities / epidemiology
  • Uterus / abnormalities
  • Uterus / diagnostic imaging

Supplementary concepts

  • Uterine Anomalies