Around a quarter of patients with repeated implantation failure have a ‘shifted implantation window’. Typically, an embryo will implant exactly 120 hours after the hormonal rise in progesterone.
The so-called implantation window can be found by undertaking an ‘Endometrial Receptivity Array Test’ (ERA-TEST) in our Kinderwunsch Institut in Linz. During the ERA-Test, undertaken at the time an embryo transfer would take place, a small tissue sample is taken from the lining of the uterus with a fine, flexible tube (pipelle) and analysed in the laboratory. The biopsy is absolutely painless and uncomplicated for most women.
If the uterine lining is found to be ‘receptive’, this means the embryo can implant exactly 120 hours after the progesterone surge. Embryo transfer can be performed in a later cycle 120 hours after starting progesterone.
If the lining of the uterus is found to be ‘non-receptive’, this means that the ‘implantation window’ has shifted. In this case, a new, individually calculated window is suggested (for example on day 4 or 6 after egg retrieval).
If the ‘personal implantation window’ of the patient is known, the embryo has a better chance of successful implantation.