What is the classification of endometriosis?

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Last updated: April 2, 2025View editorial policy

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From the Guidelines

Endometriosis should be classified using a combination of the revised American Society for Reproductive Medicine (r-ASRM) system, the Enzian classification for deep endometriosis, and the Endometriosis Fertility Index (EFI) to maximize the information available to women following surgery. This approach is based on the World Endometriosis Society consensus on the classification of endometriosis, which recommends using a toolbox for surgical classification of endometriosis to improve quality of life for women with endometriosis 1. The r-ASRM system categorizes endometriosis into four stages based on the location, extent, and depth of endometrial implants, as well as the presence and severity of adhesions and ovarian endometriomas. The Enzian classification is useful for describing deep infiltrating endometriosis, while the EFI is valuable for predicting pregnancy outcomes after surgical treatment 1.

Classification Systems

  • The r-ASRM system is the most widely accepted classification system, with four stages of disease: minimal, mild, moderate, and severe.
  • The Enzian classification is used for deep endometriosis, dividing the pelvis into compartments and grading lesion size.
  • The EFI is used to predict pregnancy outcomes after surgical treatment.

Importance of Classification

  • Classification systems help guide treatment decisions, although they may not always correlate perfectly with symptom severity or treatment response.
  • A thorough classification should consider anatomical distribution, lesion appearance, infiltration depth, and associated symptoms like pain and infertility to develop a comprehensive treatment plan tailored to each patient's specific presentation 1.

Limitations of Current Classification Systems

  • No single classification system adequately classifies endometriosis, with the exception of the EFI, which has some prognostic value 1.
  • Current classification systems have shortcomings in terms of correlation with severity of symptoms and infertility, and their impact on women's quality of life 1.

From the Research

Classification of Endometriosis

  • Endometriosis is typically classified into four stages: minimal, mild, moderate, and severe 2
  • The classification systems for endometriosis include the rASRM (American Society of Reproductive Medicine) classification, the Endometriosis Fertility Index (EFI), and the Enzian classification 3
  • The rASRM classification system is widely used and accepted worldwide, but it has limitations, such as not being sensitive in predicting pregnancy according to the stage and after treatment of the disease 4, 5

Classification Systems

  • The rASRM classification system gives a detailed description of the location and the severity of the case and correlates to some extent with the degree of pain caused by endometriosis 4
  • The Enzian classification system is considered useful for describing disease extent based on surgical findings and results of imaging methods, and for prediction of fertility, surgical complexity, and risk of surgical complications 3
  • The EFI classification system is also used to describe the extent of endometriosis, but its advantages and disadvantages need to be further discussed 3

Imaging and Classification

  • Both ultrasound (US) and MRI are used to detect pelvic endometriosis, and the choice of imaging modality should be based on the expertise in the region 6
  • Dedicated US and MRI protocols are more accurate than routine protocols in detecting pelvic endometriosis, and US has better accuracy than MRI for identifying the depth of wall invasion in bowel-wall disease 6

References

Guideline

Guideline Directed Topic Overview

Dr.Oracle Medical Advisory Board & Editors, 2025

Research

[Classification of endometriosis].

Wiener medizinische Wochenschrift (1946), 1999

Research

Endometriosis classification according to pain symptoms: can the ASRM classification be improved?

Best practice & research. Clinical obstetrics & gynaecology, 2018

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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