PubMedDate not supplied
The chances of nidation after in vitro fertilization procedures are contingent upon the development potential of the transferred embryo(s), but they also depend on the receptivity of the endometrium and on the uterine vascular supply. It is generally accepted that the chances of pregnancy are practically nil: if the endometrium is less than 8 mm thick, and/or if the uterine pulsatility index (PI) is below 3. However, the predictive value of the Doppler evaluation alone is poor to the extent that other parameters require consideration, such as the aspect of the endometrium and/or the number of embryos transferred. This is why our group initiated a prospective study on 213 patients designed to validate a 10 point scale based on: -the PI of each uterine artery on the day of transfer; -the features of the protodiastolic notch (absent, moderate or clearcut); -the thickness of the endometrium; -the number of embryos transferred. Each parameter by itself had a poor predictive value: optimal values of endometrium thickness and pulsatility index (PI) predicted a 29% and 33% pregnancy rate, which is hardly higher than our overall pregnancy rate (24%). By contrast, a score that encompasses all these parameters increased predictive value, with a score > 9 the probability of pregnancy reach 53% and the one of multiple pregnancy 24%. Our results emphasize the usefulness of a score prior embryo transfer which should be used to adjust the number of embryos transferred. When the score is higher than 10 transferring 2 embryos will prevent the risk of multiple pregnancy. 3 embryos should be transferred when the score is between 7 and 10, and a bad score (< or = 6) should delay the transfer.