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Bickendorf K, Qi F, Peirce K, Natalwala J, Chapple V, Liu Y. Spontaneous collapse as a prognostic marker for human blastocysts: a systematic review and meta-analysis. Hum Reprod 2023; 38:1891-1900. [PMID: 37581900 PMCID: PMC10546075 DOI: 10.1093/humrep/dead166] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2023] [Revised: 08/01/2023] [Indexed: 08/16/2023] Open
Abstract
STUDY QUESTION Is spontaneous collapse (SC) by human blastocysts a prognostic factor in IVF treatment? SUMMARY ANSWER SC in human blastocyst is associated with reduced euploid embryo and pregnancy rates. WHAT IS KNOWN ALREADY SC of the human blastocyst is a phenomenon that was revealed relatively recently following the clinical application of time-lapse monitoring in IVF laboratories. The ploidy and clinical prognosis of affected blastocysts are still poorly understood, with inconsistent reports. Systematic reviews and meta-analyses on this topic are currently absent in the literature but its potential as a marker of embryo viability holds great clinical value. In this study, we aimed to comprehensively evaluate the potential of SC as a prognostic factor in regard to ploidy status, and pregnancy, live birth and miscarriage rates. STUDY DESIGN, SIZE, DURATION A systematic review and meta-analysis were performed according to PRISMA guidelines, with a protocol registered with PROSPERO (CRD42022373749). A search of MEDLINE, EMBASE, and the Cochrane Library for relevant studies was carried out on 10 October 2022, using key words relevant to 'blastocyst collapse' and 'time-lapse imaging'. PARTICIPANTS/MATERIALS, SETTING, METHODS Two independent reviewers systematically screened and evaluated each study in terms of participants, exposure, comparator, and outcomes (PECO). The Quality In Prognosis Studies tool was used for quality assessment. Data were extracted according to Cochrane methods. Pregnancy, live birth, ploidy, or miscarriage data were summarized by risk ratios (RRs) or odds ratios and their 95% CIs. All meta-analyses were performed with random-effects models. MAIN RESULTS AND THE ROLE OF CHANCE Following removal of duplicates, a total of 196 records were identified by the initial search. After screening according to PECO, 19 articles were included for further eligibility assessment. For meta-analysis, seven retrospective cohort studies were eventually included. After data pooling, the incidence of blastocyst SC was 37.0% (2516/6801) among seven studies (ranging from 17.4% to 56.2%). SC was associated with significantly lower clinical pregnancy rates (two studies, n = 736; RR = 0.77, 95% CI = 0.62-0.95; I2 = 30%), ongoing pregnancy rates (five studies, n = 2503; RR = 0.66, 95% CI = 0.53-0.83; I2 = 60%), and reduced euploidy rates (three studies, n = 3569; RR = 0.70, 95% CI = 0.59-0.83; I2 = 69%). Nevertheless, live birth rates (two studies, n = 816; RR = 0.76, 95% CI = 0.55-1.04; I2 = 56%) and miscarriage rate (four studies, n = 1358; RR = 1.31, 95% CI = 0.95-1.80; I2 = 0%) did not differ between blastocysts with or without SC. There was, however, significant heterogeneity between the studies included for evaluation of ongoing pregnancy rates (I2 = 60%, P = 0.04), live birth rates (I2 = 56%, P = 0.13), and ploidy rates (I2 = 69%, P = 0.04). Subgroup analyses were conducted according to different definitions of SC, number of collapse events, and whether the transferred blastocyst had undergone preimplantation genetic testing for aneuploidy; with inconclusive findings across subgroups. LIMITATIONS, REASONS FOR CAUTION All studies in the meta-analysis were retrospective with varying levels of heterogeneity for different outcomes. Not all studies had accounted for potential confounding factors, therefore only unadjusted data could be used in the main meta-analysis. Studies employed slightly different strategies when defining blastocyst SC. Standardization in the definition for SC is needed to improve comparability between future studies. WIDER IMPLICATIONS OF THE FINDINGS Our results indicate that blastocyst SC has negative implications for a pregnancy. Such blastocysts should be given a low ranking when selecting from a cohort for intrauterine transfer. Blastocyst SC should be considered as a contributing variable when building blastocyst algorithms to predict pregnancy or live birth. STUDY FUNDING/COMPETING INTEREST(S) There is no external funding to report. All authors report no conflict of interest. REGISTRATION NUMBER PROSPERO 2022 CRD42022373749.
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Affiliation(s)
| | - Fang Qi
- Systematic Review Solutions Ltd, Shanghai, China
| | - Kelli Peirce
- Fertility North, Joondalup, Western Australia, Australia
| | - Jay Natalwala
- Fertility North, Joondalup, Western Australia, Australia
| | | | - Yanhe Liu
- Fertility North, Joondalup, Western Australia, Australia
- School of Medical and Health Sciences, Edith Cowan University, Joondalup, Western Australia, Australia
- School of Human Sciences, University of Western Australia, Crawley, Western Australia, Australia
- School of Health Sciences and Medicine, Bond University, Robina, Queensland, Australia
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Alhelou Y, Hamdan M, Razali N, Adenan N, Ali J. Novel image analyser-assisted morphometric methodology offer unique opportunity for selection of embryos with potential for implantation. BMC Pregnancy Childbirth 2023; 23:698. [PMID: 37770819 PMCID: PMC10538025 DOI: 10.1186/s12884-023-06025-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2023] [Accepted: 09/23/2023] [Indexed: 09/30/2023] Open
Abstract
BACKGROUND Previous studies looked into the connections between pregnancy and the Zona Pellucida (ZP) thickness and Zona Pellucida Thickness Variation (ZPTV), as well as the embryo's radius, circumference, perimeter and global symmetry. However, no research has linked embryo implantation and pregnancy to the percentage of ZP thinning, the reduction in ooplasm volume, and the increase in perivitelline space (PVS) volume. Our objective is to correlate the percentage of ZP thinning, the percentage of ooplasm volume shrinkage and the percentage of PVS increase to the implantation. These data will be used for embryo selection as well as it can be put into a software that will assist embryo selection. MATERIALS AND METHODS Retrospective study included 281 patients, all of them had 2 embryos transferred, 149 patients got pregnant with two gestation sacs and 132 patients did not get pregnant. All of the transferred embryos had the ZP thickness measured several times from time of ICSI till Embryo Transfer (ET), the ooplasm volume was calculated from time of ICSI till two Pronuclei (2PN) fading and the PVS was calculated from the ICSI time till the 2PN fading. RESULTS The first characteristic is the change in the average ZP thickness that decreased by 32.7% + 5.3% at 70 h for the implanted embryos (Group 1) versus 23.6% + 4.8% for non-implanted embryos (Group 2) p = 0.000. The second characteristic is the average reduction in the volume of the ooplasm which is 20.5% + 4.3% in Group 1 versus 15.1% + 5.2% in Group 2, p = 0.000. The third characteristic is the increase in the volume of the PVS which was 38.1% + 7.6% in Group 1 versus 31.6% + 9.7% in Group 2 p = 0.000. CONCLUSION The implanted embryos showed higher percent of ZP thinning, higher percent of ooplasm reduction and higher percent of PVS increase.
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Affiliation(s)
- Y Alhelou
- FAKIH IVF, Sh Haza Bin Zayed st, Abu Dhabi, United Arab Emirates.
- Department of Obstetrics and Gynaecology, Universiti Malaya, Kuala Lumpur, Malaysia.
| | - M Hamdan
- Department of Obstetrics and Gynaecology, Universiti Malaya, Kuala Lumpur, Malaysia
| | - N Razali
- Department of Obstetrics and Gynaecology, Universiti Malaya, Kuala Lumpur, Malaysia
| | - Nam Adenan
- Department of Obstetrics and Gynaecology, Universiti Malaya, Kuala Lumpur, Malaysia
| | - J Ali
- Department of Obstetrics and Gynaecology, Universiti Malaya, Kuala Lumpur, Malaysia
- IVF Department, Maternity and Children Hospital, Dammam, Saudi Arabia
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Wiegel RE, Rubini E, Rousian M, Schoenmakers S, Laven JSE, Willemsen SP, Baart EB, Steegers-Theunissen RPM. Human oocyte area is associated with preimplantation embryo usage and early embryo development: the Rotterdam Periconception Cohort. J Assist Reprod Genet 2023:10.1007/s10815-023-02803-1. [PMID: 37129725 DOI: 10.1007/s10815-023-02803-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2023] [Accepted: 04/05/2023] [Indexed: 05/03/2023] Open
Abstract
PURPOSE To investigate the association between oocyte area and fertilization rate, embryo usage, and preimplantation embryo development in order to establish if oocyte area can be a marker for optimal early embryo development. METHODS From 2017 to 2020, 378 couples with an indication for IVF (n = 124) or ICSI (n = 254) were included preconceptionally in the Rotterdam Periconception Cohort. Resulting oocytes (n = 2810) were fertilized and submitted to time-lapse embryo culture. Oocyte area was measured at the moment of fertilization (t0), pronuclear appearance (tPNa), and fading (tPNf). Fertilization rate, embryo usage and quality, and embryo morphokinetics from 2-cell stage to expanded blastocyst stage (t2-tEB) were used as outcome measures in association with oocyte area. Oocytes were termed "used" if they were fertilized and embryo development resulted in transfer or cryopreservation, and otherwise termed "discarded". Analyses were adjusted for relevant confounders. RESULTS Oocyte area decreased from t0 to tPNf after IVF and ICSI, and oocytes with larger area shrank faster (β - 12.6 µm2/h, 95%CI - 14.6; - 10.5, p < 0.001). Oocytes that resulted in a used embryo were larger at all time-points and reached tPNf faster than oocytes that fertilized but were discarded (oocyte area at tPNf in used 9864 ± 595 µm2 versus discarded 9679 ± 673 µm2, p < 0.001, tPNf in used 23.6 ± 3.2 h versus discarded 25.6 ± 5.9 h, p < 0.001). Larger oocytes had higher odds of being used (oocyte area at tPNf ORused 1.669, 95%CI 1.336; 2.085, p < 0.001), were associated with faster embryo development up to the morula stage (e.g., t9 β - 0.131 min, 95%CI - 0.237; - 0.025, p = 0.016) and higher ICM quality. CONCLUSION Oocyte area is an informative marker for the preimplantation development of the embryo, as a larger oocyte area is associated with higher quality, faster developing embryos, and higher chance of being used. Identifying determinants associated with oocyte and embryo viability and quality could contribute to improved preconception care and subsequently healthy pregnancies.
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Affiliation(s)
- Rosalieke E Wiegel
- Department of Obstetrics and Gynecology, Erasmus MC, University Medical Center, 3015 GD, Rotterdam, The Netherlands
| | - Eleonora Rubini
- Department of Obstetrics and Gynecology, Erasmus MC, University Medical Center, 3015 GD, Rotterdam, The Netherlands
| | - Melek Rousian
- Department of Obstetrics and Gynecology, Erasmus MC, University Medical Center, 3015 GD, Rotterdam, The Netherlands
| | - Sam Schoenmakers
- Department of Obstetrics and Gynecology, Erasmus MC, University Medical Center, 3015 GD, Rotterdam, The Netherlands
| | - Joop S E Laven
- Department of Obstetrics and Gynecology, Erasmus MC, University Medical Center, 3015 GD, Rotterdam, The Netherlands
| | - Sten P Willemsen
- Department of Obstetrics and Gynecology, Erasmus MC, University Medical Center, 3015 GD, Rotterdam, The Netherlands
- Department of Biostatistics, Erasmus MC, University Medical Center, 3015 GD, Rotterdam, The Netherlands
| | - Esther B Baart
- Department of Obstetrics and Gynecology, Erasmus MC, University Medical Center, 3015 GD, Rotterdam, The Netherlands
- Department of Developmental Biology, Erasmus MC, University Medical Center, 3015 GD, Rotterdam, The Netherlands
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Piquette T, Rydze RT, Pan A, Bosler J, Granlund A, Schoyer KD. The effect of maternal body mass index on embryo division timings in women undergoing in vitro fertilization. F S Rep 2022; 3:324-331. [PMID: 36568924 PMCID: PMC9783148 DOI: 10.1016/j.xfre.2022.10.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2022] [Revised: 10/08/2022] [Accepted: 10/14/2022] [Indexed: 11/05/2022] Open
Abstract
Objective To measure the impact of maternal body mass index (BMI) on the morphokinetics of embryo development as monitored by a time-lapse system. Design A retrospective chart review of in vitro fertilization (IVF) cycles from September 2016 to January 2019. Setting Academic IVF practice. Patients Patients <age 38 years undergoing IVF with their own gametes. Interventions Not applicable. Main outcome measures The primary outcome was to compare embryo division timings between morbidly obese, obese, overweight, and normal-weight patients. A multilevel mixed effects model was performed to investigate the relationships between BMI categories and embryo division timings. Log or square transformation were used to improve fit. Results A total of 366 patients met inclusion criteria, yielding 4,475 embryos: 1,948 embryos from 162 normal-weight women (BMI 18.5-24.9), 1,242 embryos from 96 overweight women (BMI 25.0-29.9), 1,119 embryos from 91 obese women (BMI 30.0-39.9), and 166 embryos from 17 morbidly obese women (BMI ≥40). There were no differences in age, Antimüllerian hormone, or IVF cycle outcomes among the different BMI categories. When comparing embryo division timings based on BMI, controlling for covariates, embryos from obese patients had a shorter time to division to 2 cell embryo (T2) than normal-weight patients. When analyzing BMI as a continuous variable, there was no significant relationship between BMI and embryo division timing. Conclusions Early embryo divisions were accelerated in only certain categories of obesity. This suggests a more complex mechanism for the effect of obesity on embryo development that may not be perceptible through the assessment of cell division timing events.
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Affiliation(s)
- Theresa Piquette
- Division of Reproductive Endocrinology and Infertility, Department of Obstetrics and Gynecology, Medical College of Wisconsin, Milwaukee, Wisconsin
| | - Robert T. Rydze
- Division of Reproductive Endocrinology and Infertility, Department of Obstetrics and Gynecology, Medical College of Wisconsin, Milwaukee, Wisconsin
| | - Amy Pan
- Division of Quantitative Health Sciences, Department of Pediatrics, Medical College of Wisconsin, Milwaukee, Wisconsin
| | - Jayme Bosler
- Division of Reproductive Endocrinology and Infertility, Department of Obstetrics and Gynecology, Medical College of Wisconsin, Milwaukee, Wisconsin
| | - Amy Granlund
- Reproductive Medicine Center, Froedtert Hospital, North Hills Health Center, Menomonee Falls, Wisconsin
| | - Kate D. Schoyer
- Division of Reproductive Endocrinology and Infertility, Department of Obstetrics and Gynecology, Medical College of Wisconsin, Milwaukee, Wisconsin,Reprint requests: Kate D. Schoyer, M.D., Division of Reproductive Endocrinology and Infertility, Department of Obstetrics and Gynecology, Medical College of Wisconsin, 8701 W. Watertown Plank Rd, Milwaukee, Wisconsin; 53226.
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Ezoe K, Coticchio G, Takenouchi H, Taoda S, Namerikawa S, Honda K, Miki T, Okimura T, Kobayashi T, Borini A, Kato K. Spatiotemporal perturbations of pronuclear breakdown preceding syngamy affect early human embryo development: a retrospective observational study. J Assist Reprod Genet 2022; 39:75-84. [PMID: 34642876 PMCID: PMC8866620 DOI: 10.1007/s10815-021-02335-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2021] [Accepted: 09/28/2021] [Indexed: 01/03/2023] Open
Abstract
PURPOSE During fertilisation, female and male pronuclei (PNs) migrate to the centre of the ooplasm, juxtapose, and break down synchronously in preparation for the first mitosis. While PN non-juxtaposition and PN breakdown (PNBD) asynchrony are occasionally observed, their developmental implications remain uncertain. This study investigated the possible relationships among the two phenomena, preimplantation development patterns, and live birth rates in single blastocyst transfers. METHODS A total of 1455 fertilised oocytes cultured in a time-lapse incubator were retrospectively analysed. Fertilised oocytes were divided into four groups according to the presence of PN juxtaposition and breakdown synchrony. The relationships of abnormal PN behaviour with embryo morphokinetics, blastocyst formation, and live birth were evaluated. RESULTS PN non-juxtaposition and asynchrony were observed in 1.9% and 1.0% of fertilised oocytes, respectively. The blastocyst cryopreservation rates in the synchronous-non-juxtaposed and asynchronous-non-juxtaposed groups were significantly lower than that in the synchronous-juxtaposed group. The rates of clinical pregnancy, ongoing pregnancy, and live birth were comparable among the groups. Non-juxtaposition was significantly associated with increased trichotomous cleavage at the first cytokinesis (P < 0.0001) and an increase in the time interval from PNBD to first cleavage (P < 0.0001). Furthermore, asynchronous PNBD was significantly correlated with increased rapid cleavage at the first cytokinesis (P = 0.0100). CONCLUSION Non-juxtaposition and asynchronous PNBD is associated with abnormal mitosis at the first cleavage and impaired preimplantation development. However, embryos displaying abnormal PNBD may develop to blastocyst stage and produce live births, suggesting blastocyst transfer as a more appropriate culture strategy.
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Affiliation(s)
- Kenji Ezoe
- Kato Ladies Clinic, 7-20-3 Nishishinjuku, Shinjuku-ku, Tokyo, 160-0023, Japan
| | - Giovanni Coticchio
- 9.Baby, Family and Fertility Center, Via Dante 15, 40125, Bologna, Italy
| | - Hitomi Takenouchi
- Kato Ladies Clinic, 7-20-3 Nishishinjuku, Shinjuku-ku, Tokyo, 160-0023, Japan
| | - Shota Taoda
- Kato Ladies Clinic, 7-20-3 Nishishinjuku, Shinjuku-ku, Tokyo, 160-0023, Japan
| | - Shima Namerikawa
- Kato Ladies Clinic, 7-20-3 Nishishinjuku, Shinjuku-ku, Tokyo, 160-0023, Japan
| | - Kasumi Honda
- Kato Ladies Clinic, 7-20-3 Nishishinjuku, Shinjuku-ku, Tokyo, 160-0023, Japan
| | - Tetsuya Miki
- Kato Ladies Clinic, 7-20-3 Nishishinjuku, Shinjuku-ku, Tokyo, 160-0023, Japan
| | - Tadashi Okimura
- Kato Ladies Clinic, 7-20-3 Nishishinjuku, Shinjuku-ku, Tokyo, 160-0023, Japan
| | - Tamotsu Kobayashi
- Kato Ladies Clinic, 7-20-3 Nishishinjuku, Shinjuku-ku, Tokyo, 160-0023, Japan
| | - Andrea Borini
- 9.Baby, Family and Fertility Center, Via Dante 15, 40125, Bologna, Italy
| | - Keiichi Kato
- Kato Ladies Clinic, 7-20-3 Nishishinjuku, Shinjuku-ku, Tokyo, 160-0023, Japan.
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Ezoe K, Miki T, Okimura T, Uchiyama K, Yabuuchi A, Kobayashi T, Kato K. Characteristics of the cytoplasmic halo during fertilisation correlate with the live birth rate after fresh cleaved embryo transfer on day 2 in minimal ovarian stimulation cycles: a retrospective observational study. Reprod Biol Endocrinol 2021; 19:172. [PMID: 34836538 PMCID: PMC8620661 DOI: 10.1186/s12958-021-00859-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/06/2021] [Accepted: 11/04/2021] [Indexed: 01/10/2023] Open
Abstract
BACKGROUND Information regarding the influence of cytoplasmic events during fertilisation on the clinical outcome remains limited. The cytoplasmic halo is one of these events. A previous study that used time-lapse technology found an association of the presence and morphokinetics of the cytoplasmic halo with cleavage patterns, development to the blastocyst stage, and the ongoing pregnancy rate after blastocyst transfer. Therefore, the cytoplasmic halo may be a useful predictor of the pregnancy outcome after cleaved embryo transfer. This study evaluated the ability of the cytoplasmic halo to predict a live birth after fresh cleaved embryo transfer on day 2, and sought to identify factors potentially influencing the presence and morphokinetics of the halo. METHODS A total of 902 embryos cultured in the EmbryoScope+® time-lapse system and subjected to single fresh cleaved embryo transfer were retrospectively analysed. The presence and duration of a cytoplasmic halo were annotated. The initial positions of the pronuclei were also observed. The correlation between the cytoplasmic halo and live birth was evaluated and the association of the cytoplasmic halo with patient, cycle, and embryonic characteristics was determined. RESULTS Absence of a cytoplasmic halo was associated with a significant decrease in the likelihood of a live birth after fresh cleaved embryo transfer. Prolongation of the halo, especially the duration of central repositioning of cytoplasmic granules, had an adverse impact on the live birth rate. The characteristics of the cytoplasmic halo were not affected by the ovarian stimulation method used, female age, the serum steroid hormone level on the day of trigger, or semen quality. However, the cytoplasmic halo was significantly affected by male age, oocyte diameter, and the initial position of the male pronucleus. CONCLUSIONS Absence or prolongation of the cytoplasmic halo was negatively correlated with the live birth rate after fresh cleaved embryo transfer. The characteristics of the cytoplasmic halo were strongly associated with oocyte diameter, male age, and the initial position of the male pronucleus. These findings indicate that the characteristics of the cytoplasmic halo can be used to select more competent embryos for transfer at the cleavage stage.
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Affiliation(s)
- Kenji Ezoe
- Kato Ladies Clinic, 7-20-3 Nishishinjuku, Shinjuku-ku, Tokyo, 160-0023, Japan
| | - Tetsuya Miki
- Kato Ladies Clinic, 7-20-3 Nishishinjuku, Shinjuku-ku, Tokyo, 160-0023, Japan
| | - Tadashi Okimura
- Kato Ladies Clinic, 7-20-3 Nishishinjuku, Shinjuku-ku, Tokyo, 160-0023, Japan
| | - Kazuo Uchiyama
- Kato Ladies Clinic, 7-20-3 Nishishinjuku, Shinjuku-ku, Tokyo, 160-0023, Japan
| | - Akiko Yabuuchi
- Kato Ladies Clinic, 7-20-3 Nishishinjuku, Shinjuku-ku, Tokyo, 160-0023, Japan
| | - Tamotsu Kobayashi
- Kato Ladies Clinic, 7-20-3 Nishishinjuku, Shinjuku-ku, Tokyo, 160-0023, Japan
| | - Keiichi Kato
- Kato Ladies Clinic, 7-20-3 Nishishinjuku, Shinjuku-ku, Tokyo, 160-0023, Japan.
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Brooks KE, Daughtry BL, Metcalf E, Masterson K, Battaglia D, Gao L, Park B, Chavez SL. Assessing equine embryo developmental competency by time-lapse image analysis. Reprod Fertil Dev 2020; 31:1840-1850. [PMID: 31759400 DOI: 10.1071/rd19254] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2019] [Accepted: 10/31/2019] [Indexed: 01/03/2023] Open
Abstract
The timing of early mitotic events during preimplantation embryo development is important for subsequent embryogenesis in many mammalian species, including mouse and human, but, to date, no study has closely examined mitotic timing in equine embryos from oocytes obtained by ovum pick-up. Here, cumulus-oocyte complexes were collected by transvaginal follicular aspiration, matured invitro and fertilised via intracytoplasmic sperm injection. Each fertilised oocyte was cultured up to the blastocyst stage and monitored by time-lapse imaging for the measurement of cell cycle intervals and identification of morphological criteria indicative of developmental potential. Of the 56 fertilised oocytes, 35 initiated mitosis and 11 progressed to the blastocyst stage. Analysis of the first three mitotic divisions in embryos that formed blastocysts determined that typical blastocyst timing (median±IQR) is 30.0±17.5min, 8.8±1.7h and 0.6±1.4h respectively. Frequent cellular fragmentation, multipolar divisions and blastomere exclusion suggested that equine embryos likely contend with a high incidence of chromosomal missegregation. Indeed, chromosome-containing micronuclei and multinuclei with extensive DNA damage were observed throughout preimplantation embryogenesis. This indicates that time-lapse image analysis may be used as a non-invasive method to assess equine embryo quality in future studies.
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Affiliation(s)
- Kelsey E Brooks
- Division of Reproductive and Developmental Sciences, Oregon National Primate Research Center, Beaverton, OR 97006, USA
| | - Brittany L Daughtry
- Division of Reproductive and Developmental Sciences, Oregon National Primate Research Center, Beaverton, OR 97006, USA; and Department of Cell, Developmental and Cancer Biology, Oregon Health and Science University School of Medicine, Portland, OR 97239, USA
| | - Elizabeth Metcalf
- Department of Obstetrics and Gynecology, Oregon Health and Science University School of Medicine, Portland, OR 97239, USA
| | - Keith Masterson
- Department of Obstetrics and Gynecology, Oregon Health and Science University School of Medicine, Portland, OR 97239, USA
| | - David Battaglia
- Department of Obstetrics and Gynecology, Oregon Health and Science University School of Medicine, Portland, OR 97239, USA
| | - Lina Gao
- Bioinformatics and Biostatistics Core, Oregon National Primate Research Center, Beaverton, OR 97006, USA
| | - Byung Park
- Bioinformatics and Biostatistics Core, Oregon National Primate Research Center, Beaverton, OR 97006, USA
| | - Shawn L Chavez
- Division of Reproductive and Developmental Sciences, Oregon National Primate Research Center, Beaverton, OR 97006, USA; and Department of Obstetrics and Gynecology, Oregon Health and Science University School of Medicine, Portland, OR 97239, USA; and Department of Physiology and Pharmacology, Oregon Health and Science University School of Medicine, Portland, OR 97239, USA; and Department of Biomedical Engineering, Oregon Health and Science University School of Medicine, Portland, OR 97239, USA; and Corresponding author.
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Apter S, Ebner T, Freour T, Guns Y, Kovacic B, Le Clef N, Marques M, Meseguer M, Montjean D, Sfontouris I, Sturmey R, Coticchio G. Good practice recommendations for the use of time-lapse technology †. Hum Reprod Open 2020; 2020:hoaa008. [PMID: 32206731 PMCID: PMC7081060 DOI: 10.1093/hropen/hoaa008] [Citation(s) in RCA: 91] [Impact Index Per Article: 22.8] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2019] [Revised: 12/05/2019] [Accepted: 01/29/2020] [Indexed: 12/26/2022] Open
Affiliation(s)
| | | | - Thomas Ebner
- Department of Gynecology, Obstetrics, and Gynecological Endocrinology, Kepler Universitätsklinikum, Linz, Austria
| | - Thomas Freour
- Médecine de la Reproduction, CHU de Nantes, Nantes, France
| | - Yves Guns
- Center for Reproductive Medicine, UZ Brussel, Brussels, Belgium
| | - Borut Kovacic
- Department of Reproductive Medicine and Gynecologic Endocrinology, Univerzitetni klinicni center Maribor, Maribor, Slovenia
| | - Nathalie Le Clef
- European Society of Human Reproduction and Embryology, Grimbergen, Belgium
| | | | - Marcos Meseguer
- IVF Laboratory, Instituto Valenciano de Infertilidad, Valencia, Spain
| | - Debbie Montjean
- Médecine et Biologie de la Reproduction, Hopital Saint Joseph, Marseille, France
| | | | - Roger Sturmey
- Centre for Atherothrombosis and Metabolic Disease, Hull York Medical School, University of Hull, Hull, UK
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Morphokinetics and in vitro developmental potential of monopronucleated ICSI zygotes until the blastocyst stage. ZYGOTE 2020; 28:217-222. [DOI: 10.1017/s0967199420000027] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
SummaryThe aim of this study was to provide a more comprehensive understanding of 1PN intracytoplasmic sperm injection (ICSI) zygotes. To achieve this objective, we assessed whether all 1PN-derived embryos showed a similar morphokinetic pattern, and if the morphokinetic behaviour of 1PN-derived embryos was comparable with that of 2PN-derived embryos. In total, 149 1PN ICSI zygotes (study group) and 195 2PN ICSI zygotes (control group) were included in the study. Embryo development potential was evaluated in terms of blastocyst rate. Morphokinetic parameters, including the pronucleus diameter and kinetics of in vitro development, were also analyzed. Embryos derived from 1PN ICSI zygotes showed impaired development compared with 2PN-derived embryos, with blastocyst rates of 28.9% and 67.2%, respectively. The diameter of the pronucleus of 1PN zygotes was larger than that of 2PN zygotes. When compared with 2PN-derived embryos, those derived from 1PN zygotes had a visible pronucleus for a shorter time, in addition to a longer syngamy time and slower kinetic behaviour from two to nine cells. When 1PN-derived blastocysts and 2PN-derived blastocysts were compared, the developmental kinetics were similar in both groups, except for a delayed and longer duration of the compaction phase in 1PN-derived embryos. In conclusion, monopronucleated ICSI zygotes present differences in developmental capacity and morphokinetic behaviour compared with 2PN ICSI zygotes, showing particular morphokinetic parameters related to pronucleus formation. Only the 1PN ICSI-derived embryos that reached the blastocyst stage have similar morphokinetic development to blastocysts from 2PN zygotes.
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Daughtry BL, Chavez SL. Time-Lapse Imaging for the Detection of Chromosomal Abnormalities in Primate Preimplantation Embryos. Methods Mol Biol 2018; 1769:293-317. [PMID: 29564832 DOI: 10.1007/978-1-4939-7780-2_19] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The use of time-lapse microscopic imaging has proven to be a powerful tool for the study of mitotic divisions and other cellular processes across diverse species and cell types. Although time-lapse monitoring (TLM) of human preimplantation development was first introduced to the in vitro fertilization (IVF) community several decades ago, it was not until relatively recently that TLM systems were commercialized for clinical embryology purposes. Traditionally, human IVF embryos are assessed by successful progression and morphology under a stereomicroscope at distinct time points prior to selection for transfer. Due to the high frequency of aneuploidy, embryos may also be biopsied at the cleavage or blastocyst stage for preimplantation genetic screening (PGS) of whole and/or partial chromosomal abnormalities. However, embryo biopsy is invasive and can hinder subsequent development, and there are additional concerns over chromosomal mosaicism and resolution with PGS. Moreover, embryos are typically outside of the incubator in suboptimal culture conditions for extended periods of time during these procedures. With TLM systems, embryos remain in the stable microenvironment of an incubator and are simultaneously imaged for noninvasive embryo evaluation using a fraction of the light exposure as compared to a stereomicroscope. Each image is then compiled into a time-lapse movie, the information from which can be extrapolated to correlate morphological, spatial, and temporal parameters with embryo quality and copy number status. Here, we describe the various TLM systems available for clinical and/or research use in detail and provide step-by-step instructions on how the measurement of specific timing intervals and certain morphological criteria can be implemented into IVF protocols to enhance embryo assessment and avoid the selection of aneuploid embryos. We also discuss the biological significance of processes unique to mitotically dividing embryos and the likelihood that complex chromosomal events such as chromothripsis occur during preimplantation development in humans and other mammals, particularly nonhuman primates.
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Affiliation(s)
- Brittany L Daughtry
- Department of Cell, Developmental and Cancer Biology, Oregon Health and Science University School of Medicine, Portland, OR, USA.,Division of Reproductive and Developmental Sciences, Oregon National Primate Research Center, Beaverton, OR, USA
| | - Shawn L Chavez
- Division of Reproductive and Developmental Sciences, Oregon National Primate Research Center, Beaverton, OR, USA. .,Department and Physiology and Pharmacology, Oregon Health and Science University School of Medicine, Portland, OR, USA. .,Department of Obstetrics and Gynecology, Oregon Health and Science University School of Medicine, Portland, OR, USA.
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Grøndahl ML, Christiansen SL, Kesmodel US, Agerholm IE, Lemmen JG, Lundstrøm P, Bogstad J, Raaschou-Jensen M, Ladelund S. Effect of women's age on embryo morphology, cleavage rate and competence-A multicenter cohort study. PLoS One 2017; 12:e0172456. [PMID: 28422964 PMCID: PMC5396884 DOI: 10.1371/journal.pone.0172456] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2016] [Accepted: 02/06/2017] [Indexed: 11/26/2022] Open
Abstract
This multicenter cohort study on embryo assessment and outcome data from 11,744 IVF/ICSI cycles with 104,830 oocytes and 42,074 embryos, presents the effect of women’s age on oocyte, zygote, embryo morphology and cleavage parameters, as well as cycle outcome measures corrected for confounding factors as center, partner’s age and referral diagnosis. Cycle outcome data confirmed the well-known effect of women’s age. Oocyte nuclear maturation and proportion of 2 pro-nuclear (2PN) zygotes were not affected by age, while a significant increase in 3PN zygotes was observed in both IVF and ICSI (p<0.0001) with increasing age. Maternal age had no effect on cleavage parameters or on the morphology of the embryo day 2 post insemination. Interestingly, initial hCG value after single embryo transfer followed by ongoing pregnancy was increased with age in both IVF (p = 0.007) and ICSI (p = 0.001) cycles. For the first time, we show that a woman’s age does impose a significant footprint on early embryo morphological development (3PN). In addition, the developmentally competent embryos were associated with increased initial hCG values as the age of the women increased. Further studies are needed to elucidate, if this increase in initial hCG value with advancing maternal age is connected to the embryo or the uterus.
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Affiliation(s)
- Marie Louise Grøndahl
- Herlev Hospital, Fertility Clinic, Copenhagen University Hospital, Herlev, Denmark
- * E-mail:
| | | | - Ulrik Schiøler Kesmodel
- Herlev Hospital, Fertility Clinic, Copenhagen University Hospital, Herlev, Denmark
- Aarhus University Hospital, Fertility Clinic, Aarhus, Denmark
| | | | | | | | - Jeanette Bogstad
- Hvidovre Hospital, Fertility Clinic, Copenhagen University Hospital, Hvidovre, Denmark
| | | | - Steen Ladelund
- Hvidovre Hospital, Statistics, Clinical Research Center, Copenhagen University Hospital, Hvidovre, Denmark
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Walls ML, Hart R, Keelan JA, Ryan JP. Structural and morphologic differences in human oocytes after in vitro maturation compared with standard in vitro fertilization. Fertil Steril 2016; 106:1392-1398.e5. [PMID: 27565256 DOI: 10.1016/j.fertnstert.2016.08.014] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2016] [Revised: 08/04/2016] [Accepted: 08/04/2016] [Indexed: 12/16/2022]
Abstract
OBJECTIVES To study whether the size and texture of oocytes/zygotes differ between in vitro maturation (IVM) and traditional IVF and to determine whether these affect the rate of fertilization and blastocyst development. DESIGN Prospective case-control study. SETTING Fertility clinic. PATIENT(S) The study involved 83 participants/cycles of IVF with intracytoplasmic sperm injection (ICSI) or IVM treatment. INTERVENTION(S) Participants were allocated to the following groups: patients with and without polycystic ovary syndrome (PCOS) undergoing ICSI (PCOS-ICSI and Control-ICSI), and patients with PCOS undergoing IVM (PCOS-IVM). All oocytes were cultured in an Embryoscope incubator. MAIN OUTCOME MEASURE(S) Oocyte/zygote sizes were recorded and texture parameters of the ooplasm were analyzed using ImageJ and maZda software. Measurements were recorded at five developmental stages: sperm injection, second polar body extrusion, the first pronuclei appearance, pronuclei disappearance, and immediately before cytokinesis. RESULT(S) Normally fertilized PCOS-IVM oocytes were significantly larger at the sperm injection and second polar body extrusion stages, compared with both the PCOS-ICSI and Control-ICSI groups. The PCOS-IVM oocytes were significantly larger at the pronuclei disappearance stage compared with the Control-ICSI group. Oocyte texture parameters were significantly different from both other treatment groups in the early developmental stages, although these were predominantly seen when compared with the Control-ICSI group. There were no significant differences in size or texture by the final stage of immediately before cytokinesis between any of the treatment groups. CONCLUSION(S) This study suggests that oocyte size and texture differ in the early stages of the first cell cycle.
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Affiliation(s)
- Melanie L Walls
- Fertility Specialists of Western Australia, Bethesda Hospital, Perth, Western Australia, Australia; School of Women's and Infant's Health, University of Western Australia, King Edward Memorial Hospital, Perth, Western Australia, Australia.
| | - Roger Hart
- Fertility Specialists of Western Australia, Bethesda Hospital, Perth, Western Australia, Australia; School of Women's and Infant's Health, University of Western Australia, King Edward Memorial Hospital, Perth, Western Australia, Australia
| | - Jeffrey A Keelan
- School of Women's and Infant's Health, University of Western Australia, King Edward Memorial Hospital, Perth, Western Australia, Australia
| | - John P Ryan
- Fertility Specialists of Western Australia, Bethesda Hospital, Perth, Western Australia, Australia; School of Women's and Infant's Health, University of Western Australia, King Edward Memorial Hospital, Perth, Western Australia, Australia
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Daughtry BL, Chavez SL. Chromosomal instability in mammalian pre-implantation embryos: potential causes, detection methods, and clinical consequences. Cell Tissue Res 2016; 363:201-225. [PMID: 26590822 PMCID: PMC5621482 DOI: 10.1007/s00441-015-2305-6] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2015] [Accepted: 09/24/2015] [Indexed: 01/08/2023]
Abstract
Formation of a totipotent blastocyst capable of implantation is one of the first major milestones in early mammalian embryogenesis, but less than half of in vitro fertilized embryos from most mammals will progress to this stage of development. Whole chromosomal abnormalities, or aneuploidy, are key determinants of whether human embryos will arrest or reach the blastocyst stage. Depending on the type of chromosomal abnormality, however, certain embryos still form blastocysts and may be morphologically indistinguishable from chromosomally normal embryos. Despite the implementation of pre-implantation genetic screening and other advanced in vitro fertilization (IVF) techniques, the identification of aneuploid embryos remains complicated by high rates of mosaicism, atypical cell division, cellular fragmentation, sub-chromosomal instability, and micro-/multi-nucleation. Moreover, several of these processes occur in vivo following natural human conception, suggesting that they are not simply a consequence of culture conditions. Recent technological achievements in genetic, epigenetic, chromosomal, and non-invasive imaging have provided additional embryo assessment approaches, particularly at the single-cell level, and clinical trials investigating their efficacy are continuing to emerge. In this review, we summarize the potential mechanisms by which aneuploidy may arise, the various detection methods, and the technical advances (such as time-lapse imaging, "-omic" profiling, and next-generation sequencing) that have assisted in obtaining this data. We also discuss the possibility of aneuploidy resolution in embryos via various corrective mechanisms, including multi-polar divisions, fragment resorption, endoreduplication, and blastomere exclusion, and conclude by examining the potential implications of these findings for IVF success and human fecundity.
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Affiliation(s)
- Brittany L Daughtry
- Department of Cell, Developmental & Cancer Biology, Graduate Program in Molecular & Cellular Biosciences, Oregon Health & Science University School of Medicine, Portland, Ore., USA
- Division of Reproductive & Developmental Sciences, Oregon National Primate Research Center, 505 NW 185th Avenue, Beaverton, OR 97006, USA
| | - Shawn L Chavez
- Division of Reproductive & Developmental Sciences, Oregon National Primate Research Center, 505 NW 185th Avenue, Beaverton, OR 97006, USA.
- Physiology & Pharmacology, Oregon Health & Science University School of Medicine, Portland, Ore., USA.
- Department of Obstetrics & Gynecology, Oregon Health & Science University School of Medicine, Portland, Ore., USA.
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Time-lapse deselection model for human day 3 in vitro fertilization embryos: the combination of qualitative and quantitative measures of embryo growth. Fertil Steril 2015; 105:656-662.e1. [PMID: 26616439 DOI: 10.1016/j.fertnstert.2015.11.003] [Citation(s) in RCA: 81] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2015] [Revised: 10/21/2015] [Accepted: 11/02/2015] [Indexed: 12/21/2022]
Abstract
OBJECTIVE To present a time-lapse deselection model involving both qualitative and quantitative parameters for assessing embryos on day 3. DESIGN Retrospective cohort study and prospective validation. SETTING Private IVF center. PATIENT(S) A total of 270 embryos with known implantation data (KID) after day 3 transfer from 212 IVF/intracytoplasmic sperm injection (ICSI) cycles were retrospectively analyzed for building the proposed deselection model, followed by prospective validation using an additional 66 KID embryos. INTERVENTION(S) None. MAIN OUTCOME MEASURE(S) Morphological score on day 3, embryo morphokinetic parameters, abnormal cleavage patterns, and known implantation results. RESULT(S) All included embryos were categorized either retrospectively or prospectively into 7 grades (A+, A, B, C, D, E, F). Qualitative deselection parameters included poor conventional day 3 morphology, abnormal cleavage patterns identified via time-lapse monitoring, and <8 cells at 68 hours postinsemination. Quantitative parameters included time from pronuclear fading (PNF) to 5-cell stage and duration of 3-cell stage. KID implantation rates of embryos graded from A+ to F were 52.9%, 36.1%, 25.0%, 13.8%, 15.6%, 3.1%, and 0 respectively (area under the curve [AUC] = 0.762; 95% confidence interval [CI], 0.701-0.824), and a similar pattern was seen in either IVF (AUC = 0.721; 95% CI, 0.622-0.821) or ICSI embryos (AUC = 0.790; 95% CI, 0.711-0.868). Preliminary prospective validation using 66 KID embryos also showed statistically significant prediction in Medicult (AUC = 0.750; 95% CI, 0.588-0.912) and Vitrolife G-Series (AUC = 0.820; 95% CI, 0.671-0.969) suites of culture media. CONCLUSION(S) The proposed model involving both qualitative and quantitative deselection effectively predicts day 3 embryo implantation potential and is applicable to all IVF embryos regardless of insemination method by using PNF as the reference starting time point.
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Liu Y, Copeland C, Chapple V, Roberts P, Feenan K, Matson P. The relationship between embryo quality assessed using routine embryology or time–lapse videography and serum progesterone concentration on the day of ovulatory trigger in in vitro fertilization cycles. ASIAN PACIFIC JOURNAL OF REPRODUCTION 2015. [DOI: 10.1016/s2305-0500(15)30011-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
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Liu Y, Chapple V, Feenan K, Roberts P, Matson P. Time-lapse videography of human embryos: Using pronuclear fading rather than insemination in IVF and ICSI cycles removes inconsistencies in time to reach early cleavage milestones. Reprod Biol 2015; 15:122-5. [DOI: 10.1016/j.repbio.2015.03.002] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2014] [Revised: 03/01/2015] [Accepted: 03/06/2015] [Indexed: 01/01/2023]
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Liu Y, Chapple V, Feenan K, Roberts P, Matson P. Clinical significance of intercellular contact at the four-cell stage of human embryos, and the use of abnormal cleavage patterns to identify embryos with low implantation potential: a time-lapse study. Fertil Steril 2015; 103:1485-91.e1. [PMID: 25914097 DOI: 10.1016/j.fertnstert.2015.03.017] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2015] [Revised: 02/24/2015] [Accepted: 03/16/2015] [Indexed: 11/28/2022]
Abstract
OBJECTIVE To investigate the clinical significance of intercellular contact point (ICCP) in four-cell stage human embryos and the effectiveness of morphology and abnormal cleavage patterns in identifying embryos with low implantation potential. DESIGN Retrospective cohort study. SETTING Private IVF center. PATIENT(S) A total of 223 consecutive IVF and intracytoplasmic sperm injection treatment cycles, with all resulting embryos cultured in the Embryoscope, and a subset of 207 cycles analyzed for ICCP number where good-quality four-cell embryos were available on day 2 (n = 373 IVF and n = 392 intracytoplasmic sperm injection embryos). INTERVENTION(S) None. MAIN OUTCOME MEASURE(S) Morphologic score on day 3, embryo morphokinetic parameters, incidence of abnormal biological events, and known implantation results. RESULT(S) Of 765 good-quality four-cell embryos, 89 (11.6%) failed to achieve six ICCPs; 166 of 765 (21.7%) initially had fewer than six ICCPs but were able to establish six ICCPs before subsequent division. Embryos with fewer than six ICCPs at the end of four-cell stage had a lower implantation rate (5.0% vs. 38.5%), with lower embryology performance in both conventional and morphokinetic assessments, compared with embryos achieving six ICCPs by the end of four-cell stage. Deselecting embryos with poor morphology, direct cleavage, reverse cleavage, and fewer than six ICCPs at the four-cell stage led to a significantly improved implantation rate (33.6% vs. 22.4%). CONCLUSION(S) Embryos with fewer than six ICCPs at the end of the four-cell stage show compromised subsequent development and reduced implantation potential. Deselection of embryos with poor morphology and abnormal cleavage revealed via time-lapse imaging could provide the basis of a qualitative algorithm for embryo selection.
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Affiliation(s)
- Yanhe Liu
- Fertility North, Joondalup Private Hospital, Joondalup, Western Australia, Australia; School of Medical Sciences, Edith Cowan University, Joondalup, Western Australia, Australia.
| | - Vincent Chapple
- Fertility North, Joondalup Private Hospital, Joondalup, Western Australia, Australia
| | - Katie Feenan
- Fertility North, Joondalup Private Hospital, Joondalup, Western Australia, Australia
| | - Peter Roberts
- School of Medical Sciences, Edith Cowan University, Joondalup, Western Australia, Australia
| | - Phillip Matson
- Fertility North, Joondalup Private Hospital, Joondalup, Western Australia, Australia; School of Medical Sciences, Edith Cowan University, Joondalup, Western Australia, Australia
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Gavriliouk D, Aitken RJ. Damage to Sperm DNA Mediated by Reactive Oxygen Species: Its Impact on Human Reproduction and the Health Trajectory of Offspring. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2015; 868:23-47. [DOI: 10.1007/978-3-319-18881-2_2] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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