Sterilization is commonly performed at which site of fallopian tube:

I have given these 2 questions simultaneously so that you understand how the answer changes as the options of the question change. Sterilization is done at the junction of proximal and middle third—the loop formed consists mainly of isthmus and part of the ampullary region of the tube. Therefore, if in options isthmoampullary is given, it is the best choice but if isthmoampullary is not given Isthmus is the next best choice.