Exploring Endometriosis Stages: Easy Understanding of Pain Levels

Dinesh Patel
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Dr. Kaushal

Review medical content on WOW Rx Pharmacy, so that accurate drug use information is easily accessible to everybody.
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endometriosis stages

Endometriosis, affecting millions of women worldwide, manifests in various stages that significantly impact both physical and emotional well-being. 

As a condition in which uterine lining-like tissue grows outside of the womb, Endometriosis progresses through four distinct stages.

From minimal to severe, these stages determine the extent of tissue spread and the severity of associated complications. 

According to a 2018 study, Endometriosis impacts approximately 176 million women worldwide, leading to a life of pain and potential infertility.

This article explores the different stages of Endometriosis and their impact on understanding severity and potential treatment options.

Stages of Endometriosis

The American Society for Reproductive Health (ASRM) classification system categorizes Endometriosis into four stages.

This classification is based on the number of lesions and the depth of infiltration:

  • Mild (Stage I) 
  • Moderate (Stage II)
  • Severe (Stage III)
  • Extensive (Stage IV)

This disease classification has a scoring system based on points.

This point system gives a numerical score for the disease, helping to understand its severity.

The disease severity or score does not always align with the level of pain or other symptoms.

  Endometriosis Stage    Score/Points    Symptoms
Mild1-5Tiny tissue growth in the pelvic lining or organs
Moderate6-15The growth penetrates deeper into the tissue
Severe16-30This stage focuses on several growths  reaching deep into the tissue
Extensive31-54Lots of thick scar tissue and deep lesions are there, and big cysts might be on one or both ovaries

Stage 1

EndometriosisSource: signaute_image
Endometriosis written on a paper

A score between one and five categorizes the severity of Endometriosis as stage 1 in women.

Such a score indicates minimal Endometriosis with small, superficial growths across the peritoneum.

In simple terms, the “peritoneum” is a thin layer of tissue that lines the inside of the abdomen and covers the organs within it, like a protective sheet.

This stage also involves growths on organs or pelvic and abdominal tissue with minimal or no scar tissue.

These scar tissues appear as tiny, flat patches or flecks that irritate and inflame nearby pelvic tissues.

This inflammation contributes to the development of adhesions, which are internal scar tissue bands. 

Adhesions can restrict the movement of normally mobile tissues and organs, resulting in pain and dysfunction.

Hence, stage 1 Endometriosis does not necessarily correlate with few or no symptoms.

It is because the superficial growth can also be mistaken for cysts or ovarian cancer.

Laparoscopic surgery is typically needed for accurate detection and classification, as imaging may not confirm minimal or mild cases.

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Stage 2

Typically, a score between six and 15 indicates stage 2. ‘

Stage 2 of Endometriosis is characterized by lesions developing in the recto-uterine pouch, located between the uterus and rectum. 

Fibrous adhesions become more aggressive, potentially leading to irritation during ovulation and pelvic pain, often identified by black spots. 

Stage 2 of Endometriosis often involves a greater number of lesions than stage 1. 

However, the majority of women diagnosed with the condition usually experience minimal or mild symptoms.

The severity of symptoms does not necessarily correlate with the extent of the disease. Some individuals with minimal visible Endometriosis may experience intense pain, while others with extensive lesions may have milder symptoms.

Stage 3

A score of 16 to 40 points places you in stage 3, characterized as a moderate form of Endometriosis.

In this stage, there are often numerous deep implants and adhesions.

Additionally, small cysts known as endometriomas or “chocolate cysts” may be present on one or both ovaries.

These cysts earn their name as the blood inside them gradually turns dark red and brown over time.

In case of these cysts rupture, it may cause excruciating discomfort in the abdomen and inflammation in the pelvis.

The resulting inflammation and infection contribute to the formation of additional adhesions.

As Endometriomas grow in size and number, so does the development of adhesions in response.

The originator of the initial description of Endometriosis remains uncertain.However, in their medical history publication titled “Endometriosis: Ancient Disease, Ancient Treatments,” Nezhat C., et al. (2012) delved into the historical account of Endometriosis, tracing it back to nearly 4000 years in pre-modern times.

Stage 4

EndometriosisSource: Getty_images
Woman suffering from pain due to Endometriosis

In this stage, a score exceeding 40 points indicates the severity of the condition.

The stage is characterized by a high number of cysts and severe adhesions.

Extensive scarring in the pelvis can spread to nearby organs or tissues in the abdomen.

Tissue build-up behind the uterus can cause severe scarring, potentially blocking the fallopian tubes and
requiring surgery.

If scarring damages the fallopian tubes, surgery might be necessary.

Endometriomas can grow significantly during this stage which is why this stage requires surgical removal for those exceeding 2 cm.

In the advanced stage, cysts on the back wall of the uterus and rectum may cause digestive issues.

These issues include painful bowel movements, constipation, nausea/vomiting, and abdominal pain.

Infertility is a common outcome in stage 4 Endometriosis when endometrial lesions, cysts, or scar tissue obstruct one or both fallopian tubes.

This blockage can sometimes manifest as the sole symptom of Endometriosis.

Some cysts may resolve on their own, while others resulting from Endometriosis typically require surgical intervention due to their growth potential.


Endometriosis stages are categorized from I to IV, with scores typically assigned across a spectrum from minimal to severe.

The higher scores correlate with more severe conditions.

These stages are classified by the American Society for Reproductive Medicine (ASRM) based on the number of lesions and their depth. 

It highlights the impact on women’s health, with stages characterized by varying symptoms, adhesions, and cysts.

The severity of the disease does not always correlate with the level of pain or other symptoms experienced by the patient. 

Endometriosis also has a potential impact on fertility, and it requires effective treatments.

Severe cases of Endometriosis may require surgery.

However, understanding and managing the condition effectively remains crucial.

Frequently Asked Questions

What are the different stages of Endometriosis?

Endometriosis is classified into four stages (I to IV) based on the extent, location, and severity of the lesions. Stage I is minimal, Stage II involves mild infiltration, Stage III exhibits moderate infiltration, while Stage IV is severe with deep infiltrating Endometriosis.

How does a doctor determine what stage a patient is in?

A doctor determines the stage using the ASRM classification, which has four stages based on lesion number and depth. A score of 16 or more may indicate a moderate or severe disease, whereas a score of 15 or less suggests minimal or mild disease. 

What does Stage 1 Endometriosis feel like?

Stage 1 Endometriosis is considered minimal because the implants are small, shallow, and smaller in number. Painful cramps during or after intercourse, bleeding in between menstrual periods, and other symptoms might all be signs of Endometriosis.

How does stage 4 Endometriosis feel?

Stage 4 Endometriosis may cause severe pelvic pain and painful menstrual cramps and is highly associated with infertility. While managing symptoms like severe pain and infertility is crucial, research into advanced treatment options for fertility preservation is ongoing, offering hope for the future. 

Can Endometriosis be diagnosed without surgery?

While Laparoscopy is the gold standard for diagnosis and staging, imaging studies like MRI may provide additional information with regard to Endometriosis. Despite the existence of such treatment, a definitive diagnosis often requires direct visualization during surgery.

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