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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 India, approximately 26 million people are diagnosed with endometriosis with an incidence of 34% to 48% when diagnosed via laparoscopy. In Korea, there was an increase in the age-adjusted prevalence rate from 2.12 per 1,000 population in 2002 to 3.56 per 1,000 population in 2013 among 15 to 54-year-old individuals based on a retrospective cohort study. 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.