A good thickness of uterine lining in the fresh protocol, in the fresh transfer is the endometrium equal and more 0.7 milimiters and more But, at the same time, studies recently showed that the thickness of the lining on the day of the embryo transfer does not have any predictive value, because the thickness we were talking before is the thickness at the late proliferative phase. We do not pay so much attention is what is happening during the 6-7 days of progesterone administration, because normally after the progesterone starts to act, when we administer it, there is supposed to be a secretarial transformation of the endometrium, and the endometrium afterward becomes more hyper echogenic and thinner because it’s becoming denser. In practical life, we can have three possible scenarios; one scenario is that the endometrium can keep growing after progesterone administration. The second one is that the thickness of the endometrium does not change after progesterone administration, and the third one is a normal change whereby it becomes thinner. So Robert Casper; the Canadian scientist recently showed very nice data. The data shows that the pregnancy rate is much higher in the case when we see compactization of the endometrium; when it has become thinner after progesterone administration. So, we repeated this data, we did the same, that is why when we meet a patient who had failed to achieve pregnancy in a previous cycle, and we see that the lining; after progesterone administration became thicker, we cancel the defrosting of the embryos and we cancel the frozen embryo transfer. We prescribe to those patients, Agonist of GnRH Gonadotropin-releasing hormone for two months to enforce that progesterone receptors work better and the after progesterone administration, endometrium looks to be thinner and estrogen activity is lower, and again this endometrium keeps growing because of extremely high estrogenic activity. These estrogens are normally to be produced by endometrium, but in some cases, like in the case of endometriosis, the endometrium predictive estrogens because of pathological expression of enzyme aromatase which converts the androgens into the estrogens and afterwards the endometrium produce a lot of estrogens which we don’t like in the profollicular surface.
Well, actually a good lining or a good thickness of the endometrium it’s everything above seven millimeters. Seven it’s sort of our baseline and everything bigger than that it’s good for us and the confirmation of the lining (have to be the famous triple line) if you can see that, you’re more confident that the endometrium is getting ready and working in the proper way.
