Endometriosis Disease Background

Last updated: 10 June 2024

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Introduction

Content on this page:

Introduction

Introduction

Endometriosis is a disease wherein an estrogen-dependent growth of endometrial-like tissues is found outside the uterus inducing a chronic inflammatory response. The pelvic organs (especially ovaries) and peritoneum are frequently affected. 

Epidemiology

Endometriosis affects 5-10% of reproductive-aged women. The prevalence is higher among Asians affecting approximately 15% of women while a lower incidence is found among African women as compared to Caucasians. In Thailand, the prevalence reports varied in terms of specific conditions from 8.6% among hospitalized patients to 78.4% among those who presented with severe dysmenorrhea.

Pathophysiology

The pathogenesis of endometriosis remains unclear, but theories include retrograde menstruation (Sampson’s theory), immune system problems, metaplastic changes of the peritoneal coelomic mesothelial cells, the spread of ectopic menstrual tissue via the bloodstream or lymphatic system, differentiation of cells from the bone marrow into ectopic endometrial tissue, and an increase in estrogen sensitivity with an increase in progesterone resistance.

Risk Factors

The risk factors for endometriosis include the following:

  • Genetics, particularly among the patient’s first-degree relatives
  • Prolonged exposure to endogenous estrogen (early menarche or late menopause)
  • Short menstrual cycle
  • Low body mass index (BMI)
  • Obstruction of menstrual flow (eg müllerian anomalies)
  • High consumption of red meat and trans fat

Classification

The types of endometriosis include adenomyosis (asymmetrical uterine enlargement), ovarian endometriomas or chocolate cysts, superficial peritoneal endometriosis, deep infiltrating endometriosis (lesions that penetrate >5 mm to the peritoneum), and disseminated endometriosis.