A tubal ligation, or having one's fallopian tubes tied, is a form of permanent contraception. However, in some cases the procedure can fail and cause an unintended pregnancy. Tubal ligations can fail for a variety of reasons including tissue or scarring that blocks the original site of ligation, recanalization (the rejoining of two separated parts), incorrect placement of clips or rings used to close off the tubes, and even organ perforation during surgery. In addition, if a woman was not at risk for ectopic pregnancies prior to her tubal ligation and develops pelvic inflammatory disease after the procedure has been completed then she may be more likely to experience a failed tubal ligation as well.