Aktueller Wissensstand zum Zeitfenster der Implantation – wie lange steht es wirklich offen?

The implantation of an embryo in the endometrium is a complex process. In the luteal phase of the menstrual cycle there is only a limited time window in which nidation can take place, the so-called implantation window. The changes in the endometrium around the time of implantation are already known in many aspects; however, it has not yet been possible to convert this knowledge into valid clinical tests to determine receptivity and to develop treatment methods for suboptimal endometrial receptivity. Many surrogate parameters for endometrial receptivity have been proposed, all of which have a poor prognostic accuracy for the onset of a clinical pregnancy in fresh and thaw cycles. It must be considered that ovarian stimulation influences the endometrial receptivity. The timing of the embryo transfer depending on the protocol used is also possibly crucial for success. In addition, disorders of the uterus which influence the endometrial receptivity and could be associated with failure of implantation must also be considered. In general, reliable markers of endometrial receptivity and more robust clinical studies are necessary.