Poor quality embryos hamper the development of high quality ones.
Although other studies provide different conclusions, the transfer of low quality embryos can impair implantation and development of top quality embryos. So, it is recommended to transfer top quality embryos alone despite the minimum number of fresh/frozen embryos in transfer cycles (2). If this is true, the question arises that how poor-quality embryos influence development and implantation of the embryos with good quality. Review of in vitro studies on prolonged culture of embryos confirms the in vivo findings. Group culture of day 3 good and low quality embryos influences the rate of high quality blastocyst formation in comparison with separate culture of low and high quality embryos. It has been postulated that different toxic compounds such as ammonia and reactive oxygen species (ROS) produced by low quality embryos have deleterious effects on quantity and quality of developed blastocysts (3). In addition, endometrial epithelial cells (EECs) and stromal cells (ESCs) of uterine tissues are very responsive to human embryos following in vitro culture. Top quality embryos enhance diffrentiation, decidualization, secretion of chemokine and growth factors that promote encapsulation and implatation of blastocyst. Therefore, good quality embryos actively intract with endometrium and promote their immplantation. In contrast, poor quality embryos inhibit selective migratory response of decidualizing ESCs and subsequent active encapsulation of themselves (4). Thus, in vitro culture of embryo and the coculture with ESCs verified the recent report of El-danasouri et al. on negative effects of poor quality embryos on implantation of good quality ones in tranfer cycles. Of course, it also should not be ignored that embryo assessments are now based on morphometric criteria which are not accurate and precise parameters. Hence, in some cases, this assessment is not consistent with functional markers of embryos. The support for this claim are the many reports on successful pregnancy following transfer of poor quality embryos or simultaneous transfer of one top and one poor quality embryo in one cycle and the incidence of having twins is 9.5% among cases (1).
In spite of the supporting evidence for influence of embryo quality on the implantation, it should be noted that all of these studies have been retrospective. The final confirmation of these findings requires numerous prospective studies with more stringent design on larger samples. Regarding partial verification of this issue, IVF centers should avoid simultaneous transfer of good and poor quality embryos in fresh and frozen/thawed cycles as much as possible. It is recommended that poor quality embryos be cultured separately and subsequently transferred or frozen if they could develop to high quality blastocysts.
(1.) Wintner EM, Hershko-Klement A, Tzadikevitch K, Ghetler Y, Gonen O, Wintner O, et al. Does the transfer of a poor quality embryo together with a good quality embryo affect the In Vitro Fertilization (IVF) outcome? J Ovarian Res. 2017;10(1):2.
(2.) El-Danasouri I, Sterzik K, Rinaldi L, Pacchiarotti A, DeSanto M, Selman H. Effect of transferring a morphologically impaired embryo with a good quality embryo on the pregnancy and implantation rates. Eur Rev Med Pharmacol Sci. 2016;20(3):394-8.
(3.) Tao T, Robichaud A, Mercier J, Ouellette R. Influence of group embryo culture strategies on the blastocyst development and pregnancy outcome. J Assist Reprod Genet. 2013;30(1):63-8.
(4.) Weimar CH, Macklon NS, Post Uiterweer ED, Brosens JJ, Gellersen B. The motile and invasive capacity of human endometrial stromal cells: implications for normal and impaired reproductive function. Hum Reprod Update. 2013;19(5):542-57.
Mohammad Reza Sadeghi
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|Author:||Sadeghi, Mohammad Reza|
|Publication:||Journal of Reproduction and Infertility|
|Date:||Apr 1, 2017|
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