Endometriosis stages explained

There have been several methods of classification of endometriosis. The system commonly used is the system of endometriosis stages. In the UK, this means the extent of endometriosis disease is graded as minimal, mild, moderate or severe. Endometriosis stages are graded differently in different countries.

Yet endometriosis can only be diagnosed by a doctor. As a surgical procedure is necessary to see the lesions. A doctor will look for endometrial lesions, preferably by laparoscopy or sometimes by laparotomy. The incision for laparoscopy is much smaller and can be performed as an outpatient procedure. Sometimes endometriosis is found during abdominal surgery for something else.

The stages of endometriosis are determined from where the lesions occur. For example, on the ovaries, or within the peritoneum. As well as how big the lesions are, and whether they are superficial or deep.

In effect the stages of endometriosis reflect the relative severity of the disease and the complexity of the surgery required to remove the endometrial tissue. Depending on how the lesions are classified it may not reflect how much total endometrial tissue there is. Neither does it refer to the amount of pain experienced.

If there are adhesions these will be examined to see if they are filmy or dense in nature. The degree to which the adhesions enclose organs or tubal structures is also taken into account.

Endometriosis can be graded by numbers from 1 to 4, or 1 to 5 in the US. Where 1 is the least and 4 (or 5) the most severe.

In the UK endometriosis stages are graded by the words, minimal, mild, moderate or severe:

• Stage 1 – minimal disease
• Stage 2 – mild disease
• Stage 3 – moderate disease
• Stage 4 – severe disease

Minimal refers to superficial or endometrial lesions, without cysts.

Mild endometriosis includes adhesions and scarring, with deeper lesions, but no cysts.

Moderate endometriosis includes cysts or endometriomas, and adhesions and scarring.

Severe endometriosis applies when there are cysts, scarring and extensive adhesions. The lesions are deep and infiltrating.

Find out more about endometriosis in my post What is Endometriosis?

Further classification could include a system based on what the endometrial lesions look like. Their colour and blood supply. As well as the relative quantities of each type.

The laparoscopy has the advantage that a surgeon may be able to remove the endometrial tissue during the procedure. Either by ablation, cauterisation or using a laser.