The Fallopian tubes are two thin tubes. It resides on each side of the uterus. It helps lead the mature egg from the ovaries to the uterus. A woman has a blocked Fallopian tube when an obstruction prevents the egg from traveling down the tube. It is also known as tubal factor infertility. This can occur on one or both sides. It is the cause of infertility in 40 percent of infertile women.