Types of endometriosis

Gain a better understanding of the three endometriosis subtypes


Just to make things a little complicated, endometriosis has three different subtypes. But don’t worry. Read this page to get up to date information about each of them.

What are the three types of endometriosis?

Endometriosis occurs differently in different people. Subtypes are categorised by where and how deep the tissue grows. Both symptoms and treatments will be different depending on what type you have. Read our diagnosis page to learn more about diagnosing each subtype.

Superficial Endometriosis

Superficial endometriosis is where endometriosis tissue grows on the lining of the abdomen and around the organs found in the abdomen. It occurs in thin patches less than 5 mm deep and is probably the most common endometriosis subtype. It’s less deep than other types but can still cause a lot of pain and problems with getting pregnant.


  • Sometimes cells are active, red spots that bleed and look a lot like the inside of the womb, but are surrounded by inflammation.
  • Cysts might be brown or look like tiny black spots, showing they have bled before.
  • Finally, other patches are whitish, probably with scarring.

Ovarian Endometriosis

With ovarian endometriosis, cysts called endometriomas grow on the ovaries. Ovarian cysts can make it hard for the ovaries to work properly, leading to fertility problems and severe pelvic pain.

Appearance and structure:

  • Cysts are often filled with dark fluid.
  • Endometriomas are sometimes called “chocolate cysts” when they are dark brown.
  • They range in size from a few millimetres to several centimetres.
  • These lesions are not cysts within the ovaries. They occur when a lesion that starts at an ovary’s surface progressively penetrates towards the centre of the ovary (imagine how a caterpillar penetrates an apple).

Unfortunately, surgical removal is difficult because the endometrioma cyst and the ovary are sometimes inseparable.

Deep Endometriosis

The most advanced subtype, deep endometriosis, is where cells like those lining the uterus’s walls have spread deeply to other organs. The lesions create scarring to other organs, making them very hard to remove.

Appearance and structure:

  • Subperitoneal lesions are hard and fibrous.
  • They penetrate greater than 5 mm in depth.
  • Hormone-dependent endometrial tissue is hardly present.

Why is this important?

Understanding the different types of endometriosis is crucial for diagnosis and treatment. Each type presents unique challenges that require tailored management strategies.

Thankfully, awareness and research into these types continue to grow, providing hope for better treatments and outcomes for those affected. While more research must be done, we’re in a good place and are hopeful for the future.

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