The Fallopian tubes are two thin, muscular tubes located between the upper (wider) part of the uterus and the ovaries. They transport the egg from the ovaries to the uterus, where it can be fertilized. The Fallopian tubes can become infected in pelvic inflammatory disease. Sometimes a fertilized egg can stop here instead of traveling to the uterus to implant. This type of ectopic pregnancy, called a tubal pregnancy, is a medical emergency, since such a pregnancy can lead to rupture of the tube and cause internal bleeding. This condition is more common in women who have had an infection in the tubes as a result of pelvic inflammatory disease, which often leads to scarring in the tubes.
Every woman has two ovaries, one on each side of the pelvic cavity. The ovaries are located at the ends of the Fallopian tubes. In addition to containing ova (eggs), the ovaries are vital in the production of the hormones estrogen and progesterone; they are analogous to the testicles in men. Each ovary is normally 3-4 cm across. Each month before a woman reaches menopause (the cessation of menstrual cycles, usually at about the age of fifty for most women), one of the ovaries releases an egg at the middle of the menstrual cycle. If the egg is not fertilized by sperm, then it does not implant in the uterus and menstruation occurs. The ovaries, too, can be infected in pelvic inflammatory disease.