What is Endometriosis
Endometriosis is an inflammatory disease process characterized by lesions of endometrial-like tissue outside the uterus that is associated with pelvic pain and/or infertility. 1, 2
Core Definition
Endometriosis is a chronic, estrogen-dependent inflammatory condition where endometrial-like tissue grows outside the uterine cavity, typically on peritoneal surfaces and pelvic organs. 2, 3 This tissue is associated with inflammation and fibrosis, affecting approximately 10% of women during their reproductive years—translating to 176 million women worldwide and 9 million in the United States. 2, 3, 4
Disease Subtypes
The disease manifests in distinct anatomical patterns:
- Superficial peritoneal endometriosis: Lesions on the peritoneal surface 1
- Ovarian endometriosis (endometriomas): Cystic lesions within the ovaries 5
- Deep endometriosis: Lesions extending deeper than 5 mm under the peritoneal surface or those involving/distorting bowel, bladder, ureter, or vagina 1, 2
Systemic Nature of the Disease
Endometriosis should be understood as a systemic disease rather than just a pelvic condition. 2, 6 The disease extends far beyond localized pelvic manifestations:
- Affects metabolism in liver and adipose tissue 6
- Causes systemic inflammation throughout the body 6
- Alters gene expression in the brain, leading to pain sensitization and mood disorders 6
- Has multifactorial etiology including genetic factors with possible epigenetic influences and environmental exposures 1, 2
Clinical Presentation
The clinical presentation is highly variable, ranging from asymptomatic to severe symptoms that significantly impact daily activities. 2
Primary symptoms include:
- Pelvic pain (present in 90% of patients): dysmenorrhea, nonmenstrual pelvic pain, dyspareunia, and dysuria 2, 3
- Infertility: Affects 26-50% of patients with endometriosis 2, 3
- Additional symptoms: Fatigue, gastrointestinal symptoms, urinary symptoms, and mood disorders 5
Pathophysiological Characteristics
The disease has several defining features beyond anatomical location:
- Hormone responsiveness: Estrogen-dependent with progesterone resistance 1, 2
- Proliferative nature: Active growth of ectopic tissue 2
- Chronic inflammation: Persistent inflammatory state 2, 4
- Pain syndrome elements: Central sensitization and altered pain processing 2
Diagnostic Challenges
A critical pitfall is diagnostic delay, averaging 5-12 years after symptom onset, with most women consulting 3 or more clinicians before diagnosis. 3 While definitive diagnosis requires surgical visualization with histological verification, clinical diagnosis can be made based on symptoms, physical examination, and imaging (transvaginal ultrasound or MRI). 3, 4 Normal examination and imaging do not exclude the diagnosis. 3
Economic and Quality of Life Impact
The economic burden is substantial at $69.4 billion annually in the United States, comparable to other chronic diseases like type 2 diabetes, Crohn's disease, and rheumatoid arthritis. 2, 4 The disease substantially affects quality of life for women and their families. 4