Endometriosis is a condition in which tissue resembling that which usually lines the uterus grows elsewhere in the body, and forms lesions.

Endometriotic lesions commonly occur in the pelvic cavity. Within the pelvic cavity, they may grow on the ovaries, the fallopian tubes, the pelvic wall, and on the bowels or bladder.

What are ovarian cysts

There are two different kinds of ovarian cysts: functional cysts and pathological cysts caused by endometriosis.

Functional ovarian cysts commonly occur in healthy women without endometriosis during the menstrual cycle. These also come into two types, and are known as follicular cysts and corpus luteum cysts.

Each egg is surrounded by a follicle, which has a protective function. Usually, when the ovaries release an egg during ovulation, the follicle ruptures and the egg travels down the fallopian tubes to the uterus. But sometimes the follicle does not rupture and continues to grow, becoming a cyst. This is called a follicular cyst.

The remnant of the follicle after ovulation is called corpus luteum. The corpus luteum releases a hormone called progesterone to prepare the lining of the uterus for pregnancy. Sometimes, fluid builds up in the corpus luteum forming a corpus luteum cyst.

Both kinds of functional cysts are usually harmless and disappear within a few months.

Pathological cysts occur when endometriosis affects the ovaries.

Endometriotic tissue can either grow on the surface on the ovary or deep inside it. Deep ovarian endometriosis is known as endometriomas or ovarian cysts. It causes the formation of cavities within the ovary that fill with blood. Over time, the blood becomes dark and looks a bit like chocolate. For this reason, ovarian cysts are also sometimes called chocolate cysts.

Endometriomas can cause severe pelvic pain and raise a serious risk of infertility. They can destroy the ovarian tissue and cause problems with ovulation. They are also associated with an increased risk of ovarian cancer.


Ovarian cysts can be detected by ultrasound, but it is usually not possible to recognize what kind of cyst is present. When a cyst is discovered, it is typically re-examined a few weeks later. A functional cyst will disappear or become smaller in the meantime.

If the cyst persists, surgery will be necessary to diagnosis its type. This is usually done by laparoscopy, a surgical procedure during which a small device is inserted through a small incision in the abdomen to examine the ovaries.


Endometriomas do not respond well to medical treatment, such as hormonal therapies.

In many cases, surgery to remove the endometriomas is the only option that leads to a lasting relief of symptoms. Removal of the endometriomas also efficiently restores fertility in most cases, and many women wanting to become pregnant do so within a short period following surgery.


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