Endometriosis is a disorder that gets its name from the endometrium, which is the tissue that lines the uterus. In endometriosis, this tissue ALSO grows outside of the uterus on various organs like: the ovaries, fallopian tubes, intestines, and tissue lining the pelvis. In mild cases of endometriosis, this abnormal growth may not cause any problems for a woman. But many women DO have symptoms like pain in the lower abdomen and pelvis. Such discomfort may be chronic, or come and go in waves. Women with the condition may also notice discomfort during sex, while ovulating, or during a bowel movement or urination. In addition, endometriosis may cause excessive bleeding during periods, or bleeding and spotting in BETWEEN periods. Fertility problems are another symptom of endometriosis, with approximately one-third to one-half of women with this condition experiencing difficulty getting pregnant. To see why endometriosis causes these problems, it's necessary to look at the menstrual cycle. Once per cycle, a woman's hormones instruct the lining of her uterus to bulk up with tissue and blood in preparation for pregnancy. If she does not get pregnant, this tissue and blood is shed through the cervix and vagina as her period. Endometriosis causes problems because the implants outside of the uterus also respond to the menstrual cycle,thickening, breaking down, and bleeding. But this process occurs outside of the uterus which means there's nowhere for this blood to go. As such, it becomes trapped in the body. Over time, this can lead to scarring and fluid filled cysts. Doctors aren't sure why endometriosis occurs, but they do know that the condition runs in families. In fact, if a woman's sister or mother is diagnosed with endometriosis, she is six times more likely to develop the condition. Additionally, the reproductive hormone estrogen can make symptoms of endometriosis worse. For this reason, the condition is most prevalent in women in their late teens to early 40's. Other factors that increase endometriosis risk, include: periods that last more than 7 days, never having children, and previous infection in the pelvic region. While endometriosis is disheartening, there are treatment options that can help. To learn more about them, watch other videos in this series.