Endometriosis is an enigmatic disease. Its origin, its development, its symptoms and its consequences constantly surprise us.

There are congresses dedicated to it and colleagues argue, for example, about the cause. They have been doing so for years and I believe that they cannot agree because they are all right. Let me explain:

The endometrium is the inner layer of the uterus, and each menstrual cycle it thickens due to the effect of the hormones produced in the ovaries to prepare the cradle for the embryo. If no embryo implants, the endometrial tissue is detached and comes out, this is called menstruation.

When there is endometrial tissue in other areas, it behaves in the same way: each month bleeding is produced and accumulates in that place, producing endometriosis foci or cysts. (When these foci are in the muscular layer of the uterus, the myometrium, we call it adenomyosis).

Why is this tissue out of place?

It may be due to a genetic predisposition. In 2021 it has been published that women carrying a variant in the NPSR1 gene are very likely to develop endometriosis. It is therefore a common disease in women of the same family.

But it can also be caused by “retrograde menstruation”: when the uterus contracts to get rid of the period, fragments of endometrium can move upwards through the tubal openings. These fragments can then nestle in the fallopian tubes.

Both causes have been proven to be possible.

What are the consequences?

As it is a phantom disease, it may not cause any symptoms and can only be seen on ultrasound, generally as cysts of old blood.

The most frequent is menstrual pain and the possible risk of causing infertility. If you have endometriosis the risk of infertility is approximately 40%.

Good! Already on my topic…

How can endometriosis cause infertility? 

It has been published that it can cause all kinds of damage but in my opinion this is not true, so I am going to talk about my experience:

The preferred locations of endometriotic tissue are the ovaries and the lining of the pelvic inner layer. Bleeding occurs in the ovaries every menstrual cycle. This accumulates to form cysts, which grow and damage the reserve of the follicles surrounding them. This can reduce the woman’s ovarian reserve. In these cases the anti-mullerian hormone may be low BUT it only indicates less quantity: endometriosis does not affect the quality of the oocytes!

Foci in the peritoneal layer can cause adhesions in the mobile part of the tubes, immobilising them and preventing them from collecting the egg. These foci secrete substances that can damage the egg when it leaves the ovary during ovulation.

When endometriosis causes infertility, the right treatment is IVF. It does not affect embryo implantation and the results are particularly good.

In severe cases, surgery is indicated to stop the cysts from growing but, if it is not absolutely necessary, we prefer to avoid it until the woman has had children because, when the cysts are removed, healthy ovarian tissue is lost and the follicle reserve is reduced.