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Endometriosis Stages Infographic

The ASRM revised classification system (rASRM) divides endometriosis into four stages based on the location, depth, and extent of implants, endometriomas, and adhesions — scored during laparoscopic surgery by a surgeon.

Stage does NOT equal pain. Stage I (Minimal) can be severely debilitating, while Stage IV (Severe) can cause little to no pain. The rASRM score measures anatomical extent of disease — it does not predict your quality of life, fertility outcomes, or how much a treatment will help. This is one of the most important — and most commonly misunderstood — facts about endometriosis.
Endometriosis Stages I–IV — ASRM Classification Infographic A four-panel infographic illustrating the revised American Society for Reproductive Medicine (rASRM) staging system for endometriosis. Each panel shows a stylised cross-section of the pelvic anatomy with lesions, implants, adhesions, and endometriomas that correspond to that stage. Stage I (Minimal, score 1–5): a few superficial peritoneal implants. Stage II (Mild, 6–15): more implants, slightly deeper penetration, minimal adhesions. Stage III (Moderate, 16–40): many deep implants, small endometriomas (chocolate cysts) on ovaries, some filmy adhesions. Stage IV (Severe, above 40): extensive deep implants, large bilateral endometriomas, dense widespread adhesions. Endometriosis Stages — rASRM Classification 1 5 6–15 15 16–40 40 >40 rASRM score Stage I Minimal · Score 1–5 Depth: superficial only • Few isolated implants • No adhesions • Ovaries unaffected • Peritoneal surface only rASRM: 1–5 pts Stage II Mild · Score 6–15 Depth: superficial–moderate • More implants, deeper • Minimal/no adhesions • Possible ovary surface spots • Cul-de-sac may be involved rASRM: 6–15 pts Stage III Moderate · Score 16–40 cyst Depth: deep infiltrating • Many deep implants • Small endometrioma ≤3 cm • Filmy adhesions present • Cul-de-sac partial obliteration rASRM: 16–40 pts Stage IV Severe · Score >40 cyst ≥3cm cyst Depth: extensive, bilateral • Extensive deep implants • Large endometriomas ≥3 cm • Dense widespread adhesions • Complete cul-de-sac obliteration rASRM: >40 pts endotracking.com · Educational only — not medical advice · Staging requires laparoscopic surgery by a specialist

The rASRM staging system scores endometriosis on a 1–150+ point scale based on the number, size, and depth of lesions found during laparoscopy. The four stages are cut-offs within that scale, not discrete disease types.

Stage Summary

Stage Name Score What it means anatomically
I Minimal 1–5 A few isolated superficial peritoneal implants; no adhesions; ovaries and tubes typically normal.
II Mild 6–15 More implants, some slightly deeper; minimal or no adhesions; cul-de-sac may be lightly involved.
III Moderate 16–40 Many deep implants; small endometriomas (≤3 cm) on one or both ovaries; filmy adhesions present; partial cul-de-sac obliteration.
IV Severe >40 Extensive deep implants; large bilateral endometriomas (≥3 cm); dense widespread adhesions; complete cul-de-sac obliteration possible.

Why stage doesn't equal pain — and why that matters

The biology

The rASRM score is an anatomical measure — it counts and sizes lesions visible to a surgeon through a laparoscope. Pain, by contrast, is driven by nerve sensitisation, inflammatory cytokine levels, and individual pain-processing differences that no score captures.

What this means for you

A Stage I diagnosis does not mean your pain is "minor." A Stage IV diagnosis does not mean you will suffer more than anyone else. If your symptoms are dismissed because of a low stage number, that is not good medicine. Symptom severity should drive treatment decisions alongside — not below — staging.

The only way to stage

Endometriosis staging requires diagnostic laparoscopy — a surgical procedure. Ultrasound and MRI can detect endometriomas and deep infiltrating disease but cannot assign a formal rASRM score. If you have not had surgery, you do not yet have an official stage.

For a deeper look at what staging means day-to-day, read our article: Understanding Endometriosis Stages. For living with symptoms at any stage, see Endometriosis Pain Management Strategies.

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