Endometrial Dating Method Detects Individual Maturation Sequences During the Secretory Phase

BACKGROUND/AIMThis study assessed whether a new immunohistochemical dating method allows precise endometrial dating allowing optimal timing for embryo transfer. PATIENTS AND METHODSA novel method was used for endometrial dating, with parameters including menstrual cycle days, Noyes histological criteria, along with immunohistochemical expression pattern of estrogen and progesterone receptors and proliferation marker Ki-67. Endometrial maturation was analyzed on days +5 to +10 after ovulation or progesterone administration in 217 biopsies from 151 subfertile patients during the secretory phase. RESULTSEndometrial maturation varied individually, occurring 1.68±1.67 days late. Comparison of histological maturation with clinical days after ovulation showed a delay of about 2 days. CONCLUSIONEndometrial maturation requires 8 days, rather than the expected 6 days, to reach the histological mid-secretory phase. This is not a delay and is also seen in fertile patients. The new analysis method used is superior to that using Noyes criteria alone and provides a better basis for determining conditions for optimal timing of embryo transfers.