We've just found out our 2nd IVF cycle hasn't worked and are struggling to accept our infertility is 'unexplained' and what to look into things before doing a FET with the 1 embryo we have frozen. We done 1 ICSI cycle last year which failed, an IUI which failed earlier this year and our 2nd ICSI cycle last month and feel like we need more tests before spending money on more cycle that might end up with the same result because we aren't fixing a problem that's there, surely there has to be a reason. So beyond the usually hormone blood tests, Hycosy for me and semen analysis & Karyotyping for DH what other tests have you ladies done? I've been reading about NK cells which can be tested and looks for reason why implantation may not be taking place, has anyone had this? Did you think it was worth the £500 or so it costs?