Comprehensive evaluation of the incidence and prevalence of surgically diagnosed pelvic endometriosis in a complete population

Abstract

Introduction: The incidence and prevalence of pelvic endometriosis is still being debated. Population-based studies have shown annual incidences between 0.1% and 0.3%, which translates to a prevalence of symptom-giving disease of between 2% and 6% over a 20-year span in the reproductive years. However, a prevalence of 10% or higher is often assumed. We used Iceland's extensive record linkage possibilities, secure access to patient data and personal identification numbers to search for all cases with a surgical and/or histological first diagnosis over a 15-year study period.

Material and methods: Information was obtained from all healthcare facilities where an operative and/or histological diagnosis of pelvic endometriosis might have been made during 2001-2015. Hospital discharge diagnostic data and private clinic data sources were scrutinized and double-checked through a central register. Individual medical records, operation notes and pathology records were inspected. Visually and pathologically diagnosed cases were included. The data covered women aged 15-69 years, but the age range 15-49 (reproductive years) was specifically considered. Annual incidence was estimated per 10 000 person-years and prevalence possibilities calculated for varying disease durations. Disease severity was staged (revised American Society for Reproductive Medicine classification) and main lesion sites determined.

Results: A total of 1634 women 15-69 years old were diagnosed; 1487 of them between 15 and 49 years old. Histological verification was obtained for 57.1%. The age-standardized annual incidence for all confirmed endometriosis diagnoses was 12.5/10 000 person-years among women in their reproductive years. The overall estimate of prevalence was 0.6%-3.6%, dependent on duration of symptoms from 5 up to 30 years. The most common sites by order of frequency were ovaries, deep pelvis, central pelvis, vesicouterine pouch and uterine appendages. Of the women, 1080 (66.1%) had minimal/mild and 553 (33.8%) moderate/severe disease.

Conclusions: We have in a comprehensive study covering a recent 15-year period confirmed an annual incidence of pelvic endometriosis of between 0.1% and 0.15% in the female population of reproductive age. Endometriosis is variably severe but, depending on the duration of symptomatic disease, the approximated prevalence during women's reproductive years could range from 1% to 4%.

Keywords: endometriosis; histology; incidence; operative; population; surgical procedures.