Incidence of endometriosis by study population and diagnostic method: the ENDO study

Fertil Steril. 2011 Aug;96(2):360-5. doi: 10.1016/j.fertnstert.2011.05.087. Epub 2011 Jun 29.


Objective: To estimate the incidence of endometriosis in an operative cohort of women seeking clinical care and in a matched population cohort to delineate more fully the scope and magnitude of endometriosis in the context of and beyond clinical care.

Design: Matched-exposure cohort design.

Setting: Surgical centers in the Salt Lake City, Utah, and San Francisco, California, areas.

Patient(s): The operative cohort comprised 495 women undergoing laparoscopy/laparotomy between 2007 and 2009, and the population cohort comprised 131 women from the surgical centers' catchment areas.

Intervention(s): None.

Main outcome measure(s): Incidence of endometriosis by diagnostic method in the operative cohort and by pelvic magnetic resonance imaged (MRI) disease in the population cohort.

Result(s): Endometriosis incidence in the operative cohort ranged by two orders of magnitude by diagnostic method: 0.7% for only histology, 7% for only MRI, and 41% for visualized disease. Endometriosis staging was skewed toward minimal (58%) and mild disease (15%). The incidence of MRI-diagnosed endometriosis was 11% in the population cohort.

Conclusion(s): Endometriosis incidence is dependent on the diagnostic method and choice of sampling framework. Conservatively, 11% of women have undiagnosed endometriosis at the population level, with implications for the design and interpretation of etiologic research.

Publication types

  • Comparative Study
  • Multicenter Study
  • Research Support, N.I.H., Intramural

MeSH terms

  • Adult
  • Biopsy
  • Cohort Studies
  • Endometriosis / diagnosis*
  • Endometriosis / epidemiology*
  • Endometriosis / surgery
  • Epidemiologic Research Design
  • Female
  • Humans
  • Incidence
  • Laparoscopy*
  • Magnetic Resonance Imaging*
  • Predictive Value of Tests
  • Severity of Illness Index
  • United States / epidemiology