The fallopian tubes normally transport the egg of the female from the egg sac, or ovary, to the womb, or uterus. Normal tubes have small hair like projections on the lining cells called cilia. These cilia are important to movement of the egg through the fallopian tube and into the uterus. If the tubal cilia are damaged by infection, the egg may not get 'pushed along' normally and can settle in the tube. Likewise, if infection causes partial blockage of the tube with scar tissue, this can also act to prevent the egg from getting to the uterus. Any process that narrows the tube and thus decrease the caliber of the passage way can increase the chance of an ectopic pregnancy. Examples of these would be endometriosis, tumours, or scar tissue in the pelvis (pelvic adhesions) that cause twisting or chinking of the tube.