When confronted with “unexplained” IVF failures where morphologically good embryos were transferred, the question arises as to whether the problem is due to inherent egg/embryo “incompetence” (which usually equates with an irregular chromosomal configuration [aneuploidy]) or whether it is due to an implantation dysfunction. The younger the woman and the higher the quality of available embryos (preferably blastocysts), the less likely it is that the fault lies with embryo “incompetence” and the greater is the likelihood that it is due to underlying implantation dysfunction.

The most common causes of implantation dysfunction are:

  1. A “thin uterine lining”
  2. A uterus with surface lesions in the cavity (polyps, fibroids, scar tissue)
  3. Immunologic implantation dysfunction (IID)

Implantation dysfunction (anatomical or immunologic) is a common cause of repeated “unexplained” IVF failure with good embryos. This is especially the case in young ovulating women who have normal ovarian reserve and have fertile partners. Failure to identify, typify, and address such issues is, in my opinion, an unfortunate and relatively common cause of repeated IVF failure in such women.