Assessing the endometrium: An update on current and potential novel biomarkers of receptivity

A cyclical evolvement of the endometrium into a transient state of receptivity is crucial for acceptance of the semi-allogeneic foetus, conducive to pregnancy. Despite documentation of aberrances in this process within patients experiencing repeated embryo implantation failures and miscarriages, the endometrium is often overlooked in IVF clinics as the cause for failure. Focus instead is usually given to embryo-derived factors, such as aneuploidy. Nevertheless, failure of approximately 30 % of euploid embryos to implant demonstrates that other factors such as the endometrium require clinical exploration. Here, we review both traditional and novel methods used to assess endometrial receptivity such as identifying the WOI, endometrial immune profiling and transcriptomics panel testing. Where reported, we will also discuss their clinical application, as well as novel potential biomarkers within the pre-clinical research stages which show promise in their ability to assess endometrial receptivity.