Female Reproductive System


Last update: 13-06-2023

How else can it be called?

  • ICD-10: N80

What is endometriosis?

Endometriosis is a disease that primarily affects women and is characterized by the abnormal growth of endometrial tissue outside the uterus, in various locations throughout the body.

The endometrium, a soft tissue lining inside the uterus, plays a crucial role in each menstrual cycle by shedding and causing the characteristic bleeding.

In cases of endometriosis, the presence of endometrial tissue extends beyond the uterus. It can be found near the uterus, such as in the fallopian tubes and ovaries. Moreover, it can also appear outside the uterus in various locations, including the bladder, rectum, abdomen, scars from previous surgeries, and in rare instances, it may even reach the lungs or the meninges in the brain.

The primary concern arises from the fact that the endometrium, even when located outside the uterus, continues to respond to sex hormones as if it were still within the uterine cavity. This abnormal response can lead to a variety of issues, including bleeding, adhesions, and pain in the affected areas.

Endometriosis is a chronic and recurrent disease that not only causes abdominal pain, typically intensifying after menstruation, but is also associated with infertility. However, its impact extends beyond these symptoms, potentially leading to various complications when endometrial tissue is found in other organs.

Endometriosis is generally considered a benign condition that does not progress into cancer.

Which are the possible causes?

The exact causes of endometriosis remain unclear, giving rise to numerous theories attempting to explain its occurrence.

The leading theory regarding the cause of endometriosis is retrograde menstruation, which suggests that a portion of the endometrial tissue flows backward into the fallopian tubes and implants itself in other organs outside the uterus.

Additional researchers have put forth alternative explanations, including stem cell migration from the bone marrow, the concept of endometrial cells migrating through the blood as "benign metastases," and several other hypotheses. However, despite extensive exploration, a definitive conclusion regarding the precise cause of endometriosis has yet to be reached.

Consequently, the elusive nature of its origins presents challenges in terms of prevention and treatment.

What is the incidence of the disease?

Endometriosis affects a significant proportion of women of childbearing age, estimated to be between 5% and 10% from the onset of their first period until menopause.

Endometriosis is a highly prevalent condition, with approximately 30 to 40% of women experiencing fertility issues attributing them to this cause. It is noteworthy that a significant number of these women affected by endometriosis have not yet had any children.

Furthermore, endometriosis accounts for over 70% of women seeking medical attention due to chronic pelvic pain.

Which are the main symptoms?

The symptoms of endometriosis can vary significantly, ranging from asymptomatic cases to severe pain and the formation of large ovarian cysts with blood retention.

Women affected by endometriosis may experience a range of symptoms, including:

  • Dysmenorrhea: Pelvic pain before and during menstrual periods, accompanied by menstrual cramps.
  • Pain and symptoms in other locations before and during the menstrual period: The specific symptoms depend on the site of endometrial implantation. For instance, it may cause pain in the rectum, dyschezia (functional disorder of bowel coordination), burning sensation during urination, or even coughing up blood.
  • Dyspareunia: Pain during sexual intercourse.
  • Irregular intermenstrual bleeding and abnormal blood loss.
  • Women with endometriosis often have somewhat shorter menstrual cycles, typically lasting less than 27 days, and experience prolonged menstrual bleeding for more than seven days.
  • Infertility.

The intensity of symptoms associated with endometriosis does not always align with the severity of the disease. It is possible for women with mild endometriosis to experience severe pelvic pain, while others with extensive lesions may remain asymptomatic.

Endometriosis can lead to infertility by impeding the passage of the egg cell (ovum) through the fallopian tubes to reach the uterus, primarily due to the presence of abnormal tissue. However, it is important to note that infertility can occur even in cases where there are no apparent anatomical abnormalities associated with endometriosis.

How can it be diagnosed?

Typically, endometriosis is suspected during the evaluation of infertility or sterility through comprehensive medical history, physical examination, and relevant diagnostic tests.

Furthermore, it is not uncommon to discover endometriosis when assessing women who have been experiencing persistent pelvic pain for an extended period.

Vaginal examination, visualization using a vaginal speculum, and transvaginal ultrasound can aid in detecting endometriosis located near the uterus. However, the definitive diagnosis of endometriosis is typically confirmed through laparoscopy.

Laparoscopy is a diagnostic procedure that enables the visualization of endometrial lesions and facilitates the collection of biopsy samples. It involves the insertion of a thin tube fitted with a camera through a small incision in the abdominal area. Additionally, laparoscopy offers the advantage of simultaneous surgical treatment if necessary.

While previously recommended for all women with suspected endometriosis, current practice favors initiating less invasive procedures as an initial approach, reserving laparoscopy for cases where treatment is required or when diagnostic uncertainty remains.

The recommended initial tests for the evaluation of endometriosis include:

  • Transvaginal ultrasound.
  • Pelvic Magnetic resonance imaging (MRI).

If there is suspicion of endometrial seeding in other regions of the body, the following diagnostic procedures may be conducted:

  • Transanal endoscopy.
  • Colonoscopy.
  • X-ray studies with contrast to assess potential obstructions in the intestines or urinary tract.
  • Abdominal and whole-body magnetic resonance imaging (MRI).
  • Chest MRI if lung involvement is suspected.
  • Cranial MRI if there is suspicion of endometrial seeding in the meninges (extremely rare).

Which is the recommended treatment?

The treatment approach for endometriosis varies based on the severity of symptoms and focuses on achieving three primary goals:

  1. Pain treatment
  2. Sterility and infertility treatment
  3. Managing deep endometriosis involving organs at risk

In general, there are two main treatment options available:

  • Pharmacological therapy
  • Surgical intervention
  1. Pain treatment:

    Chronic pain associated with endometriosis can be challenging to manage, and conventional treatments such as nonsteroidal anti-inflammatory drugs (NSAIDs), antidepressants, or anticonvulsants may not always provide effective relief.

    The effectiveness of hormone treatments for endometriosis varies among individuals. The following options are available:

    • Contraceptives, such as pills, vaginal rings, or patches, are often beneficial for managing dysmenorrhea and dyspareunia.
    • Progestins (synthetic progestogens) are used to reduce estrogen levels. However, they may have side effects such as weight gain, fluid retention, or headaches. Commonly prescribed progestins include medroxyprogesterone acetate and norethindrone acetate. Additionally, the insertion of a levonorgestrel IUD (Mirena®) is an alternative. Dienogest® (a derivative of nortestosterone) has also shown promising results.
    • Gonadotropin-Releasing Hormone (GnRH) agonists are employed if other methods fail to provide pain control. However, they can cause bothersome symptoms like vaginal dryness, hot flashes, weight gain, and may lead to osteoporosis.
    • GnRH antagonists are utilized when other treatments prove ineffective.
    • Aromatase inhibitors, such as letrozole and anastrozole, may be combined with hormone treatments for specific cases.

    Previously commonly prescribed medications like Danazol have fallen out of favor in recent times due to their associated side effects. Danazol works by altering androgens, progesterone, and corticosteroids, leading to various undesirable effects, including acne, weight gain, bleeding between periods, edema (fluid retention), cramps, deepening of the voice, and increased facial hair. Consequently, it is no longer recommended unless no alternative treatment options are available.

    The decision for surgical intervention in endometriosis greatly depends on the extent of the condition and the woman's desire to preserve fertility. There are two main approaches:

    • Non-radical surgery: This procedure is typically performed laparoscopically with the goal of
      • Being as aggressive as necessary in removing endometrial tissue outside the uterus.
      • Being as conservative as possible with the organs, especially if the patient intends to conceive in the future.
    • Radical surgery: Involves a total hysterectomy along with bilateral salpingo-oophorectomy, which entails the removal of the uterus, fallopian tubes, and ovaries. This approach results in sterility and the cessation of menstruation in the future.

  2. Sterility and infertility treatment

    • Surgical treatment with laparoscopy: This approach is recommended when there are specific causes of infertility, such as obstructions or large masses that hinder the passage of the egg cell (ovum).
    • Assisted reproduction techniques (ART).
    • It is crucial to provide patients with comprehensive counseling, explaining the potential risks associated with pregnancy in the presence of endometriosis.

  3. Deep endometriosis management

    • Pain management as previously discussed.
    • For abdominal endometriosis affecting the peritoneum, lesion removal through laparoscopy is typically performed.
    • In cases of ovarian endometriosis, surgical intervention and laser removal may be considered.
    • Deeply infiltrating endometriosis often requires a complex surgical intervention involving a gynecologist, abdominal surgeon, and urologist. Prior antibiotic preparation is necessary. In some instances, partial removal of the bladder or colon may be required.
    • Pulmonary or meningeal endometriosis necessitates a multidisciplinary team within highly specialized medical centers due to the complexity of the condition.
Medically reviewed by Yolanda Patricia Gómez González Ph.D. on 13-06-2023


  • Clinical Reproductive Medicine and Surgery. A Practical Guide. Third edition.Tommaso Falcone, William W. Hurd. ISBN 978-3-319-52209-8. Pag 433.
  • Coloproctology. 2nd edition. 2017. Alexander Herold, Paul-Antoine Lehur, Klaus E. Matzel, P. Ronan O’Connell. ISBN 978-3-662-53208-9. Pag 241.
  • Fertility Preservation and Restoration for Patients with Complex Medical Conditions. Allison L. Goetsch, Dana Kimelman, Teresa K. Woodru. 2017. ISBN 978-3-319-52315-6. Pag 217.
  • European Society of Human Reproduction and Embryology. ESHRE Guideline Endometriosis - Issued: 2 February 2022. Available on: https://www.eshre.eu

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