In fact, there are many reasons for failed embryo transfer during in vitro fertilization such as: The woman has uterine adhesions, poor embryo quality, thin uterine lining, submucosal fibroids... or immune disorders in the mother after embryo transfer.

To conduct a uterine immunoassay after embryo transfer, the preparation is quite simple. The frozen embryo transfer cycle is usually performed on days 18-22 of the menstrual cycle.