Skip to content

Types of endometriosis

There are 3 types of endometriosis lesions

From a teaching point of view, endometriosis lesions are classified into 3 major groups, one patient can be affected by all of them together.
These endometriosis lesions can theoretically be found anywhere in the pelvis and abdomen and more rarely in the thorax.

Superficial, peritoneal lesions

Superficial, peritoneal lesions are probably the most frequent lesions and are located in the peritoneum.

They are small, superficial lesions, for which the depth of infiltration does not exceed 5 mm.

They can have different appearances:

  • Sometimes they are active, red lesions, very similar to the endometrium, frequently haemorrhagic, surrounded by an inflammatory reaction. (a)
  • Other lesions are a brownish color (b), or appear as black microcysts (c), indicating and old hemorrhage.
  • Finally, others are whitish, probably with scarring, and attest to a healing process (d).

Cystic lesions of the ovaries

Cystic lesions of the ovaries (ovarian endometriomas) are haemorrhagic lesions that encyst under the ovarian parenchyma and progressively displace it.

Varying in size from a few mm to several cm, these lesions are not really intra-ovarian cysts. They are the result of intra-ovarian invagination of a lesion initially on the surface of the ovary, which progressively invaginates into the ovary like a caterpillar penetrates an apple.

This specificity makes their surgical treatment awkward, as the endometrioma and the ovary are sometimes inseparable, which can lead to damage to the ovary during removal of the cyst.

Deep, subperitoneal lesions

Deep, subperitoneal lesions (infiltration greater than 5 mm) are hard, fibrous lesions in which the hormone-dependent endometrial tissue is relatively little represented (15-20% of the volume of the endometriosis nodule).

These lesions have a tendency to infiltrate the surrounding organs, behaving aggressively much like tumours, leanding to the appearance of severe forms, the removal of which is increasingly difficult.

Because of their fibrous composition, and as they are not very hormone-dependent, the size of deep endometriosis nodulesllittle impacted by amenorrhea, which simply allows the disease to stabilize, but rarely to disappear.

This explains why they may be found in postmenopausal women and smptomatic despite definitive amenorrhea.

It is estimated that endometriosis may affect one in 10 women in France, without symptoms or such severe forms such as those described above. It is likely that the disease follows a pyramidal distribution, with superficial lesions at the base (in the vast majority of women) and severe deep lesions at the top (in a minority of cases).

Types of
in numbers


of women with endometriosis have ovarian endometriomas


of women with endometriosis have a deep lesion


of women with digestive endometriosis have lesions on the diaphragm

Source :
1. Yang et al, RBMO 2015
2. Zondervan et al, Nature reviews 2018
3. Roman et al, Hum reprod 2020


What is endometriosis?

The symptoms

What are the symptoms of endometriosis?

The diagnosis

How is endometriosis diagnosed?


What are the treatments for endometriosis?

Get help from endometriosis specialists

For multidisciplinary management of endometriosis, IFEM Endo accompanies you throughout your care journey of medical and surgical treatment, medical follow-up and pain management.

Last updated on May 4, 2021 @ 08:08