Many ovarian cysts occur with endometriosis. Chocolate cysts are so named because they are filled with excess blood that has turned dark red or chocolate brown in color. This is a commonly seen problem in endometriosis.

How It Happens

In endometriosis, the endometrial tissue, regardless of location, will change with the amount of hormones in the body. During a normal reproductive cycle, the levels of estrogen and progesterone will often irritate the extra endometrial tissue, causing swelling. Since endometrial tissue of this type (abnormal endometrial tissue) does not exit the body along with normal healthy tissue, the blood and tissue continues to be trapped in the ovarian cysts. If the cysts rupture, the old blood will be dislodged.

Infertility

Chocolate cysts may play a role in infertility. Because this type of cyst is composed of extra endometrial tissue, it will continue to stay in the reproductive system, potentially interfering with the normal monthly shedding of the uterine lining. For the best chances to conceive, it is necessary for the uterus and ovaries to be as healthy as possible and free of extra tissue, so chocolate cysts can create problems in the area of fertility.