The term failed implantation is not really a diagnosis – it’s just descriptive ! It’s a bit like the word hypertension , which simply tells us that the patient has high blood pressure , but really doesn't tell us anything more. Similarly, failure to implant just means that the transferred embryos did not implant within the endometrium , but it does not tell us why they failed to do so – or what we can do differently the next time around to improve the chances of success . There are limits to our science , and when you're putting a microscopic ball of cells inside the uterus, it’s very hard to track it fate to determine what went wrong ! The simple truth is – we do not know why most IVF cycle fail ! There are only three tangibles we can monitor during IVF treatment: embryo quality ; the uterine lining; and the ease of the actual transfer procedure. Even if all these are perfect, most embryos will not become babies, because human reproduction is not a very efficient enterprise – and this is true, whether it’s in vitro or in vivo ! Just because your embryos did not implant in the first cycle does not reduce your chances in the next cycle, but few patients are mature enough to accept that doctors don’t have all the answers !
There is a lot of pressure on the doctor to provide an answer, which is why doctors are then forced to cook these up . They then run a battery of expensive tests , in order to find out why the “the uterus rejected the embryo” ! Amongst these sophisticated pseudoscientific tests, a very popular one is the one which tests for the activity of NK cells . This has very little value , because fertile women are as likely to have “high NK activity” as infertile women – but because they have enough sense not to go to a doctor to get their NK cell activity tested, they do not know this – and neither do their doctors !
Patients need to accept that even though our technology is limited in its ability to answer why embryos fail to implant, it’s still very good at allowing us to bypass problems , if they are willing to be patient !