Chances of pregnancy are poor if your tubes were tide. But it has been reported that as the time passes, clamps become loose and sperms can pass through it and fertilization can take place. In this case, pregnancy will be ectopic. As your tubes were ligated 7 years ago, then there are chances that these may have become loose. So, you should take pregnancy test if you are suspecting pregnancy. If test is positive then termination of pregnancy is needed.