What are the different types of endometriosis?

Types of Endometriosis

Endometriosis is classified into three main anatomical types based on location and depth of invasion: superficial peritoneal endometriosis, ovarian endometriomas (cysts), and deep infiltrating endometriosis (DIE), with DIE defined as lesions extending deeper than 5 mm under the peritoneal surface or involving bowel, bladder, ureter, or vagina. 1

Primary Anatomical Classification

Superficial Peritoneal Endometriosis

• Characterized by endometrial-like tissue implants on the peritoneal surface of pelvic organs 2
• These lesions remain on the surface and do not penetrate deeply into underlying tissue 1
• Represents the most common form encountered during laparoscopy 1

Ovarian Endometriomas

• Cystic lesions within the ovary containing endometrial-like tissue and old blood 2
• Can be reliably detected through transvaginal ultrasound with 82.5% sensitivity and 84.6% specificity 3
• Often referred to as "chocolate cysts" due to their characteristic appearance 4

Deep Infiltrating Endometriosis (DIE)

• Defined specifically as lesions extending deeper than 5 mm beneath the peritoneal surface 1, 5
• Includes lesions that involve or distort the bowel, bladder, ureter, or vagina 1
• Represents the most severe anatomical form with significant impact on quality of life 2
• Can be mapped preoperatively using expanded protocol transvaginal ultrasound or MRI 2

Clinical Presentation Subtypes

Pain-Predominant Endometriosis

• Manifests primarily with chronic pelvic pain, dysmenorrhea, dyspareunia, and dysuria 2, 3
• Pain typically shows progressive worsening over time and extends beyond menstruation 3
• Associated with systemic inflammation and central pain sensitization 6

Infertility-Associated Endometriosis

• Approximately 50% of patients with endometriosis experience infertility 2, 3
• Affects at least one-third of women presenting with infertility 3
• May be asymptomatic aside from difficulty conceiving 2

Asymptomatic Endometriosis

• Discovered incidentally during surgery for other indications 2
• Highlights the variable clinical presentation of the disease 2

Important Clinical Considerations

Systemic Disease Recognition

• Endometriosis should be understood as a systemic inflammatory disease, not merely a pelvic condition 2, 6
• The disease affects metabolism in liver and adipose tissue, causes systemic inflammation, and alters gene expression in the brain leading to pain sensitization and mood disorders 6
• This broader understanding is critical for comprehensive treatment planning 6

Pathophysiologic Characteristics

• All types demonstrate estrogen-dependence and progesterone resistance 2
• Characterized by chronic inflammation and fibrosis 2
• Lesions have proliferative nature regardless of anatomical location 2

Classification System Limitations

Current System Deficiencies

• The r-ASRM classification system, while widely used, has very poor correlation with pain symptoms and quality of life 1
• The r-ASRM system does not adequately describe deep endometriosis 1
• When using r-ASRM classification, the Enzian classification system should be employed concurrently when deep endometriosis is present to provide complete operative description 1

Practical Approach

• Despite limitations, r-ASRM remains in use due to its longevity, widespread clinical acceptance, and prevalence in medical literature 1
• The Endometriosis Fertility Index (EFI) is a validated tool specifically for predicting fertility outcomes following surgical staging 1

Common Pitfalls to Avoid

• Do not assume symptom severity correlates with anatomical extent of disease—the r-ASRM staging has very poor correlation with pain and quality of life 1
• Do not delay empiric treatment waiting for surgical confirmation—diagnosis is fundamentally clinical and laparoscopy with histologic confirmation is no longer required before initiating therapy 3
• Do not overlook deep infiltrating disease when using standard classification systems—supplement r-ASRM with Enzian classification when DIE is suspected 1
• Do not treat endometriosis as solely a gynecologic condition—recognize its systemic manifestations affecting multiple organ systems 2, 6