Endometriosis is a chronic disease that affects 10-15% of women of childbearing age and causes infertility in 30% of them.

It occurs when endometrial tissue, which is the tissue that lines the inside of the uterus, implants outside the uterus and invades the abdominal organs such as the ovaries, tubes, bladder, liver, intestine, rectum, etc. It is a chronic and progressive disease, so early diagnosis is essential to minimise the negative effects on fertility.

As it is progressive, it evolves up to four levels: from minimal to mild, to moderate, and to severe at stage IV. About 15% of patients are diagnosed at stage IV and their quality of life and general health are seriously affected.

Patients present different symptoms such as

  • Dysmenorrhoea: painful menstruation.
  • Dyspareunia: painful sexual intercourse.
  • Pelvic, abdominal, lumbar pain: depending on the degree of endometriosis and its location.
  • Intestinal disorders: including food intolerances, constipation or diarrhoea.
  • Urinary incontinence: particularly if the endometriosis affects the excretory system.
  • Haematuria: presence of blood in urine.
  • Tiredness and fatigue: worsens as the disease progresses.
  • Infertility: this is one of the key causes in the diagnosis of the disease.

The symptoms of endometriosis do not depend on the degree of progression of the disease, and these symptoms are equally relevant in women with mild and more severe endometriosis. However, a direct relationship between infertility and the degree of endometriosis is known.

Cysts called endometriomas can occur in the ovary, which in addition to reducing healthy ovarian tissue and therefore the ovarian reserve, also affect the quality of the oocytes, which reduces the chances of pregnancy. On the other hand, adhesions cause tubal obstruction, which makes these patients candidates for IVF.

One of the problems we encounter is the complexity of diagnosis in some patiens and the general lack of awareness of the relevance of this pathology, which means that the average time to obtain a diagnosis is 8 to 12 years.

For this reason, the ESHRE (European Society of Human Reproduction) has drawn up professional consensus guidelines for dealing with cases of endometriosis in women seeking pregnancy.

An exhaustive anamnesis may lead us to suspect endometriosis, but the diagnosis will be made with vaginal ultrasound, a technique recommended as reliable and non-invasive where endometriomas can be seen, with the use of diagnostic laparoscopy being increasingly discouraged due to its complexity, being an invasive procedure, as well as its economic cost.

Endometriosis is sometimes detected directly in the IVF laboratory after follicular fluid aspiration during egg retrieval. This finding usually occurs in patients with no previous suspicion of endometriosis. On these occasions, rapid action by the laboratory is essential to minimise the exposure time of the eggs to “contaminated” follicular fluid.

The presence of endometriosis, particularly when located in the ovarian tissue, has a negative effect on egg quality. This deleterious effect is directly related to the inflammatory environment and the oxidative stress associated with it. These characteristics can affect both ovarian function and the quality of eggs and embryos. The presence of endometriomas has been reported to have a negative impact on the egg retrieval rate as well as on the proportion of mature eggs obtained after controlled ovarian stimulation.

This result is already a limitation in the possibilities of successful treatment in these patients. Other studies have evaluated the development potential of embryos generated after IVF in women with endometriosis, comparing these results with other women without the disease. The effect of endometriosis on embryo quality appears to be moderate, particularly because it does not extend to the entire ovary and remains localised in the area where the endometrioma has appeared. Therefore, it is the characteristics of the endometrioma itself that determine the functionality of the ovary according to its size and degree of severity.  Faced with this scenario, the IVF laboratory will always work considering the presence of endometriosis as a threat to the health of the patient’s eggs, since the possible leakage of endometriosis remains into the follicular fluid can alter the conditions of the follicular fluid, and thus affect the eggs. In cases where oocytes are recovered in follicular fluid containing traces of endometriosis, they would be separated as quickly as possible, and washed repeatedly in a clean culture medium to remove any remaining endometriosis.

Endometriosis has a negative impact on pregnancy outcomes after IVF. Firstly, because they have a lower rate of mature egg retrieval than expected. This influences the final number of viable embryos for transfer or cryopreservation.

Despite all this, patients with endometriosis are able to obtain good quality embryos.

However, patients with endometriosis have lower gestation rates than other patient groups as a result of altered endometrial receptivity due to the inflammatory process as well as a local production of progesterone-resistant oestrogens, which may hinder the proper development of the endometrium for embryo implantation.

Recommendations For Patients With Endometriosis Who Wish To Have Children

Given the importance of endometriosis as a cause of infertility in women, it is very important that women diagnosed with endometriosis receive appropriate and timely reproductive counseling.

In the case of younger women who do not yet wish to become mothers, the option of egg vitrification is highly recommended. This option gives them the opportunity to postpone motherhood, preserving “younger” eggs that may be less affected by the disease, particularly in cases of less advanced endometriosis.

If, on the other hand, the woman affected by endometriosis has the desire to become a mother, she can resort to assisted reproduction treatments when pregnancy has not been achieved naturally. Once again, it is important to know the degree of the condition in order to assess the chances of pregnancy in each case.

Dr. Carmen Calatayud

Co-director of CREA

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