All contraceptive methods have a risk of pregnancy occurring during use. Among the contraceptive methods available, tubal ligation is the most effective. The treatment consists of blocking the uterine tubes to prevent the union of egg and sperm.
Although it may be thought that the uterine or fallopian tubes are merely a tunnel through which the sperm, egg and embryo pass, this is not true. The uterine tubes have several functions, its tissue helps the movement of the sperm and the egg so that they come together in its outermost third, secretes nutritional molecules that establish an optimal environment for the development of the embryo and then helps the embryo formed to move into the uterus where it will finally implant.
When a tubal ligation is performed, it is possible that it will reopen, spontaneously recanalize. This will hinder the movement of the embryo to the interior of the uterus, so the embryo can be trapped in the tube, implanting inside it and developing a pregnancy outside the uterus called an ectopic pregnancy.