When patients fail repeated IVF cycles, the "diagnosis" their doctor offers them is - Implantation Dysfunction .
However, this is really just a waste paper basket diagnosis - it does not provide any useful actionable information . It's a mouthful, but it's just a description of the fact that their embryos have consistently failed to implant for an unknown reason.
Making a diagnosis - and receiving one - often gives both patients and doctors a lot of comfort, because they feel that once they have been able to put a name to the problem, they will be able to tackle it better. Sadly, this is often just a delusion !