The normal tissue that lines the inside of the uterine cavity and bleeds during the menstrual period is called the endometrium.

Endometriosis is a chronic inflammatory hormone-dependent benign disease in which endometrial-like tissue develops outside the uterine cavity. Typically this disease occurs in the pelvis, but it can also occur in any part of the body. The most common locations of endometriosis are the outer surface of the ovaries, the anterior peritoneal reflection (tissue located between the uterus and bladder), the structures behind the uterus (uterosacral ligaments, uterine torus, retrocervical region), the uterus, fallopian tubes, vagina, intestine and bladder.

Causes

The exact cause of endometriosis is still unknown, but several theories are suggested:

• Retrograde menstruation – menstrual bleeding and tissue are directed in the reverse direction, ie they go from the uterus to the pelvis through the fallopian tubes.
• Endometrial tissue from the uterus can be transported through the blood and lymph vessels to any extra-uterine site, including the pelvis.
• Changes in the immune system allow endometrial tissue outside the uterus to grow and develop.
• Coelomic metaplasia is the concept that cells of the peritoneum and ovarian surface can transform into endometrial tissue with certain stimuli, such as irritation from retrograde menstruation or infection.
• Genetic and epigenetic.

Dr. William Kondo

General Surgeon and obstetrician -gynecologist specializing in pelvic surgery, laparoscopy and Endometriosis.​