What Causes Endometriosis

The exact cause of endometriosis is not well understood, but there are several theories.

  • Problems with menstrual period flow. One theory is that endometriosis occurs when some of the menstrual blood containing endometrial cells flows backward through the fallopian tubes and into the pelvic cavity instead of leaving the body during menstruation. These cells can then implant and grow outside the uterus, leading to endometriosis.
  • Immune system problems. Another theory suggests that endometriosis may be caused by a problem with the immune system, which may fail to recognize and destroy the misplaced endometrial cells. Immune system disorders and certain cancers are more common in women with endometriosis.
  • Hormones. Hormones are also thought to play a role in the development of endometriosis. Specifically, estrogen has been implicated as a contributing factor, as endometriosis tends to develop and grow in response to estrogen.
  • Genetic factors. Genetics may also play a role in the development of endometriosis. Women who have a family history of the condition are at higher risk of developing it themselves.
  • Surgery. During a surgery to the abdominal area, such as a Cesarean (C-section) or hysterectomy, endometrial tissue could be picked up and moved by mistake. For instance, endometrial tissue has been found in abdominal scars.
  • Endometrial cell transport. The blood vessels or tissue fluid (lymphatic) system may transport endometrial cells to other parts of the body.

Environmental factors. Exposure to certain environmental toxins and chemicals may increase the risk of developing endometriosis.

Risk factors

Several factors place you at greater risk of developing endometriosis, such as:

  • Never giving birth
  • Starting your period at an early age
  • Going through menopause at an older age
  • Short menstrual cycles — for instance, less than 27 days
  • Heavy menstrual periods that last longer than seven days
  • Having higher levels of estrogen in your body or a greater lifetime exposure to estrogen your body produces
  • Low body mass index
  • One or more relatives (mother, aunt or sister) with endometriosis
  • Any medical condition that prevents the passage of blood from the body during menstrual periods
  • Disorders of the reproductive tract

Endometriosis usually develops several years after the onset of menstruation (menarche). Signs and symptoms of endometriosis may temporarily improve with pregnancy and may go away completely with menopause, unless you’re taking estrogen.

It’s important to note that while these are some of the theories about what causes endometriosis, the exact cause is still not fully understood.

It is likely that endometriosis is caused by a combination of these factors, rather than a single cause. More research is needed to fully understand the cause of endometriosis and develop better treatments.