Impact of early cleaved zygote morphology on embryo development and in vitro fertilization-embryo transfer outcome: a prospective study
ABSTRACT To evaluate the impact of the first division morphology on embryo development and IVF-embryo transfer outcome.
Teaching hospital, France.
All zygotes from 201 couples were checked for early cleavage. We defined as "even," early cleaved (EC) zygotes with 2 cells of even size; as "uneven," EC zygotes with 2 cells of uneven size; and as "fragmented," EC zygotes with more than 20% fragmentation rate. Day 2 embryo quality was assessed as "top" embryo or "non-top," with the evaluation of multinucleated blastomeres.
Day 2 embryo quality, pregnancy and implantation rates.
Among EC zygotes, 59.1% were even, 13.0% were uneven, and 27.9% were fragmented. Even EC yielded more "top" embryos and less multinucleated blastomere embryos than uneven EC (77.0% vs. 46.3%) and fragmented EC (77.0% vs. 13.9%). The 125 double embryo transfers that comprised at least one embryo derived from even EC zygote led to higher pregnancy rate (PR) (64.0% vs. 43.4%) and implantation rate (42.0% vs. 27.6%) compared to the 76 double embryo transfers with embryos derived from breakdown or 2PN zygotes.
The morphology of the early cleaved zygote is involved in embryo development. Evaluation of this morphology is an effective and valuable method of assessing the embryo quality.
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ABSTRACT: The morphology of fertilization events has been related to successful implantation by subjective criteria (pronuclei score, pronuclei symmetry and position). This work first described these events by time-lapse technology and then compared the timings of fertilization events (second polar body extrusion, first and second pronuclei appearance, abuttal and fading) in implanted versus nonimplanted embryos in a 2-year cohort retrospective study. A total of 1448 transferred embryos from 842 patients undergoing intracytoplasmic sperm injection with oocyte donation were monitored, 212 embryos from treatments where the number of gestational sacs matched the number of transferred embryos and 687 embryos from treatments no biochemical pregnancy was achieved. The timings at which second polar body extrusion (3.3–10.6 h), pronuclear fading (22.2–25.9 h) and length of S-phase (5.7–13.8 h) occurred were linked successfully to embryo implantation. The other parameters were apparently not related, as determined by image acquisition and time-lapse analysis.Reproductive biomedicine online 04/2014; 28:475-484. DOI:10.1016/j.rbmo.2013.11.014 · 2.98 Impact Factor
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ABSTRACT: Time-lapse observation presents an opportunity for optimizing embryo selection based on morphological grading as well as providing novel kinetic parameters, which may further improve accurate selection of viable embryos. The objective of this retrospective study was to identify the morphokinetic parameters specific to embryos that were capable of implanting. In order to compare a large number of embryos, with minimal variation in culture conditions, we have used an automatic embryo monitoring system. Using a tri-gas IVF incubator with a built-in camera designed to automatically acquire images at defined time points, we have simultaneously monitored up to 72 individual embryos without removing the embryos from the controlled environment. Images were acquired every 15 min in five different focal planes for at least 64 h for each embryo. We have monitored the development of transferred embryos from 285 couples undergoing their first ICSI cycle. The total number of transferred embryos was 522, of which 247 either failed to implant or fully implanted, with full implantation meaning that all transferred embryos in a treatment implanted. A detailed retrospective analysis of cleavage times, blastomere size and multinucleation was made for the 247 transferred embryos with either failed or full implantation. We found that several parameters were significantly correlated with subsequent implantation (e.g. time of first and subsequent cleavages as well as the time between cleavages). The most predictive parameters were: (i) time of division to 5 cells, t5 (48.8-56.6 h after ICSI); (ii) time between division to 3 cells and subsequent division to 4 cells, s2 (≤ 0.76 h) and (iii) duration of cell cycle two, i.e. time between division to 2 cells and division to 3 cells, cc2 (≤ 11.9 h). We also observed aberrant behavior such as multinucleation at the 4 cell stage, uneven blastomere size at the 2 cell stage and abrupt cell division to three or more cells, which appeared to largely preclude implantation. The image acquisition and time-lapse analysis system makes it possible to determine exact timing of embryo cleavages in a clinical setting. We propose a multivariable model based on our findings to classify embryos according to their probability of implantation. The efficacy of this classification will be evaluated in a prospective randomized study that ultimately will determine if implantation rates can be improved by time-lapse analysis.Human Reproduction 08/2011; 26(10):2658-71. DOI:10.1093/humrep/der256 · 4.59 Impact Factor
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ABSTRACT: Embryo selection is based on embryo developmental and morphological characteristics. Standard embryo evaluation has some disadvantages. New technology using multilevel images combined with a computer-assisted scoring system (CASS) has the potential to overcome these disadvantages. The aim of this study was to compare the value of a computer-assisted scoring system (CASS) versus a standard scoring system (SSS) in predicting implantation and live birth. This prospective study included 3185 embryos obtained during 502 IVF/intracytoplasmic sperm injection cycles with single-embryo transfer on day 3. Embryos were evaluated with two scoring systems: SSS and CASS. Logistic regression analyses were performed using implantation and live birth as outcomes. According to multiple regression analysis, implantation was influenced by number and size of blastomeres on day 3 using CASS and by all embryo parameters on day 3 using SSS. Combined analysis of both scoring systems revealed that implantation was affected by number and size of blastomeres using CASS and by the degree of embryo fragmentation using SSS. Using live birth as outcome, only the number of blastomeres on day 3, evaluated by SSS and CASS, was predictive. Prediction of implantation and live birth may be superior using CASS when compared with SSS.Reproductive biomedicine online 05/2011; 23(3):347-54. DOI:10.1016/j.rbmo.2011.05.007 · 2.98 Impact Factor