IUI After two years ttc after a loss and three unsuccessful clomid cycles, my doctor has me starting…

IUI

After two years ttc after a loss and three unsuccessful clomid cycles, my doctor has me starting letrozole next month. If no success, I'll have my first iui in September. Now I don't know too much about IUIs, I always thought they were pretty intrusive, much like ivf, but after some research I think i might be wrong. Has anyone had an iui in the past? I wondering what, if any, the pain might be. Thanks!