<prompt> Least failure in sterilization occurs with:Falope ringBipolar cauteryUnipolar cauterisationHulka clip  <response>: Female tubal sterilization methods-10 year cumulative failure rates:Unipolar cauterisation 0.75Postpartum tubal excision 0.75Silastic ringfallope ring 1.77Interval tubal exclusion 2.01Bipolar coagulation 2.48Hulka - clemens clips 3.65Note: Although unipolar cauterization has least failure rates, but is not preferred method for female steriliization as it leads to serious gastrointestinal burns. 