Endometriosis is a condition in which the cells that make up the lining of the uterus (endometrium) are found in places outside the uterus.
The causes of endometriosis are not fully understood. Our knowledge about its development and the factors that trigger it are being refined as research progresses.
The most popular theory of the cause of endometriosis is the theory of retrograde menstruation. This theory says that when the uterus sheds its lining through the vagina during the menstrual period a small proportion of the menstrual fluid flows backwards through the fallopian tubes into the pelvic cavity. This menstrual fluid contains cells from the endometrial lining that are still living. When these living cells are deposited into the pelvic cavity they implant (attach) themselves onto the tissue on which they land. These implanted cells become endometrial implants or deposits.
This theory (like all the theories on the causes of endometriosis) explains how endometriosis develops but not why it develops. Finding out what triggers the development of endometriosis is the subject of much research around the world. Research suggests that oestrogen, environmental toxins and a genetic predisposition are some of the factors responsible for the development of endometriosis – but how these factors contribute is not understood as yet.
It may help to make a list of your symptoms and when you experience them as well as a list of any questions you have before your appointment so you don’t forget anything important. Consider taking a close relative or friend with you for support. You may have a pelvic examination during your consultation. This may be uncomfortable and embarrassing but it can help to determine the likelihood of endometriosis. You may also be asked to have a vaginal ultrasound. An ultrasound cannot detect endometrial implants but it can detect endometriomas and other abnormalities that may be contributing to your symptoms. A vaginal ultrasound gives a clearer image than an abdominal ultrasound. If your symptoms and menstrual history indicate you could have endometriosis you will be advised to have a laparoscopy to confirm the diagnosis because endometriosis cannot be diagnosed conclusively without one. A laparoscopy is an operation in which a thin telescope-like instrument called a laparoscope is inserted nto the pelvic cavity through a small cut near the navel (belly button).
For more information about having a laparoscopy read the booklet ‘Preparing for a Laparoscopy’ which can be downloaded from the Endometriosis Association (Qld) Inc. – available on our website www.qendo.org.au
The endometrial deposits respond to the hormones of the menstrual cycle in the same way as the lining of the uterus. Each month they grow and swell with blood and then break down and bleed. They bleed directly onto the surrounding tissues, which causes irritation and inflammation. This leads to pain, the development of scar tissue around the deposit, and sometimes the development of adhesions.
Most endometrial implants are found in the pelvic cavity. Common sites are the ovaries, peritoneum, pouch of Douglas and uterosacral ligaments. Less common sites include the appendix, surface of the bladder, surface of the uterus, fallopian tubes, surface of the small and large bowel, and rectovaginal septum.
There are three different types of endometriosis. Endometrial implants or deposits are usually 1–2 mm in diameter but may be so small they can be seen only with a microscope. They look like a small dot or cluster of small dots. They may be clear, red, black or white depending on their age and stage of development. They are most commonly found on the surface of the peritoneum.
Endometrial nodules vary in shape and size but are usually elongated lumps about 2–3 mm in size.
They are often difficult to see because they tend to lie below the peritoneum and infiltrate into the underlying tissues. They are most commonly found in or near the uterosacral ligaments, pouch of Douglas and rectovaginal septum.
Endometriomas are endometrial cysts 1–10 cm in diameter that are found in or on the ovary. They are often called ‘chocolate cysts’ because they contain old dark blood that has the consistency of melted chocolate.