How common is endometriosis?
According to the Centers for Disease Control and Prevention, more than 5 million women in the United States have endometriosis. This is about 10 to 15 percent of all women in their reproductive years. However, the exact incidence of the condition is likely even higher. This is because women without symptoms or fertility problems may have endometriosis without knowing it.

What is endometriosis?
Endometriosis is a condition in which the cells that form the tissue that lines the uterus, which is called the endometrium, grow in locations outside the uterus. Endometrial tissue consists of glands, blood cells and connecting tissue called stromal cells. The tissue responds to your monthly hormonal changes whether it is in your uterus or located elsewhere.

The displaced tissue of endometriosis, which is called endometrial implants or lesions, grows and expands as it would in your uterus. However, it cannot leave the body the way the uterine tissue does during menstruation. As a result, the implants can bleed into other areas or inflame other organs and form scar tissue or adhesions. This may result in severe pain and damage to your organs, especially your reproductive organs.

What do endometrial implants look like?
Endometrial implants begin microscopically small, often as clear lesions. With time, they become larger and darker and can take many shapes. The colors vary, ranging from red, brown or black to clear, white, yellow or pink. The prevailing color may depend on the blood supply, age of the lesion and other nearby tissue. Some endometrial lesions look like other scars or inflammations and may need an experienced surgeon to recognize them as endometriosis.