Status of nucleolar channel systems in uterine secretions accurately reflects their prevalence-a marker for the window of implantation-in simultaneously obtained endometrial biopsies

NCS status of secretions accurately reflects NCS prevalence of biopsies, a marker for the implantation window. As secretion aspiration is compatible with same-day ET, our study provides proof of principle for a minimally invasive approach to determine endometrial receptivity for timing frozen ET.