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Gynecological Endocrinology Publication details, including instructions for authors and subscription information: http://www.tandfonline.com/loi/igye20
Blastocyst-stage versus cleavage-stage embryo transfer in the first frozen cycles of OHSS-risk patients who deferred from fresh embryo transfer a
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b
a
a
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Hua Chen , Jie-Qiang Lv , Xin-Mei Wu , Yu Xiao , Hai-Tao Xi , Chun-Fang Zhu , Jian-Ying a
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Huang , Fan Zhang & Hong-Shan Ge a
Reproductive Medicine Center, The 2nd Affiliated Hospital & Yuying Children’s Hospital of WenZhou Medical University, WenZhou, China and b
Department of Clinical Laboratory, The 2nd Affiliated Hospital & Yuying Children’s Hospital of WenZhou Medical University, WenZhou, China Published online: 20 Jul 2015.
Click for updates To cite this article: Hua Chen, Jie-Qiang Lv, Xin-Mei Wu, Yu Xiao, Hai-Tao Xi, Chun-Fang Zhu, Jian-Ying Huang, Fan Zhang & Hong-Shan Ge (2015): Blastocyst-stage versus cleavage-stage embryo transfer in the first frozen cycles of OHSS-risk patients who deferred from fresh embryo transfer, Gynecological Endocrinology To link to this article: http://dx.doi.org/10.3109/09513590.2015.1062858
PLEASE SCROLL DOWN FOR ARTICLE Taylor & Francis makes every effort to ensure the accuracy of all the information (the “Content”) contained in the publications on our platform. However, Taylor & Francis, our agents, and our licensors make no representations or warranties whatsoever as to the accuracy, completeness, or suitability for any purpose of the Content. Any opinions and views expressed in this publication are the opinions and views of the authors, and are not the views of or endorsed by Taylor & Francis. The accuracy of the Content should not be relied upon and should be independently verified with primary sources of information. Taylor and Francis shall not be liable for any losses, actions, claims, proceedings, demands, costs, expenses, damages, and other liabilities whatsoever or howsoever caused arising directly or indirectly in connection with, in relation to or arising out of the use of the Content. This article may be used for research, teaching, and private study purposes. Any substantial or systematic reproduction, redistribution, reselling, loan, sub-licensing, systematic supply, or distribution in any form to anyone is expressly forbidden. Terms & Conditions of access and use can be found at http:// www.tandfonline.com/page/terms-and-conditions
http://informahealthcare.com/gye ISSN: 0951-3590 (print), 1473-0766 (electronic) Gynecol Endocrinol, Early Online: 1–4 ! 2015 Informa UK Ltd. DOI: 10.3109/09513590.2015.1062858
ORIGINAL ARTICLE
Blastocyst-stage versus cleavage-stage embryo transfer in the first frozen cycles of OHSS-risk patients who deferred from fresh embryo transfer Hua Chen1, Jie-Qiang Lv1, Xin-Mei Wu2, Yu Xiao1, Hai-Tao Xi1, Chun-Fang Zhu1, Jian-Ying Huang1, Fan Zhang1, and Hong-Shan Ge1 Downloaded by [Nanyang Technological University] at 06:57 27 August 2015
1
Reproductive Medicine Center, The 2nd Affiliated Hospital & Yuying Children’s Hospital of WenZhou Medical University, WenZhou, China and Department of Clinical Laboratory, The 2nd Affiliated Hospital & Yuying Children’s Hospital of WenZhou Medical University, WenZhou, China
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Abstract
Keywords
Elective cryopreservation of all embryos has been the most effective means to avoid developing ovarian hyperstimulation syndrome (OHSS). However, it is still unknown which stage is optimal for freezing and transferring into uterus in OHSS-risk patients. This study was undertaken to evaluate whether OHSS-risk patients could benefit from transferring blastocysts. A total of 162 women were allocated to cleavage-stage embryo transfer (ET) (group A ¼ 70) and blastocysts transfer (group B ¼ 92) on the basis of patients’ voluntary in their first frozen cycles. Although the mean number of transferred embryos in group A was significantly more than those in group B (2.37 ± 0.52 versus 2.11 ± 0.52, p50.05), the clinical pregnancy rates, implantation rates and live birth rates in group B were significantly higher than those in group A (47.83% versus 31.43%, p50.05; 31.44% versus 18.67%, p50.05; 40.21% versus 27.14%, p50.05), and the multiple pregnancy rates in both groups were comparable (34.09% versus 36.36%, p40.05). The observed results in OHSS-risk population allow us to take a position in favor of blastocyst transfer, thus pregnancy and live birth could be achieved with fewer ETs and in a shorter time frame.
Blastocyst transfer, cleavage-stage embryo, first frozen cycle, OHSS-risk patients
Introduction Ovarian hyperstimulation syndrome (OHSS), with the incidence of 5–10%, is the most frequent serious complication from ovarian stimulation in in vitro fertilization (IVF) [1]. The mild form is of only minor relevance, while its severe form is life-threatening. Given the iatrogenic nature of this condition, it is particularly important to minimize the risk of developing OHSS in women receiving fertility treatment. Several strategies have been described to reduce the incidence and severity of OHSS in a high-risk population. So far, the strategy refraining from fresh embryo transfer (ET) and elective cryopreservation of all embryos for future frozen-thaw transfer, allowing a reasonable chance of achieving pregnancy, could be the most effective means to resolve the challenge. Really, avoiding fresh ET in OHSS-risk patients has been confirmed in several reports, and acceptable pregnancy was achieved with frozen embryo transfer (FET) [2–4]. However, Are cleavage-stage morphological parameters reliable enough to determine embryo viability, or is it better to culture embryos to blastocyst? Which stage is optimal for freezing and transferring into uterus remains a matter of debate. This study aims to compare the efficacy of transferring thawed embryos at the cleavage-stage or at blastocyst-stage in the first Address for correspondence: Hong-Shan Ge, Reproductive Center, The 2nd Affliated Hospital & Yuying Children’s Hospital of Wenzhou Medical University, Wenzhou, China. Tel: +86-577-88002612. Fax: +86577-88002622. E-mail: [email protected]
History Received 31 July 2014 Accepted 12 June 2015 Published online 20 July 2015
frozen-thawed cycles of patients who deferred from fresh ET because of high risk for OHSS, and to suggest a practice model of elective cryopreservation of more promising embryos, which would result in better clinical outcomes with fewer ETs and in shorter time frame.
Methods Patients population This prospective study was conducted from May 2012 to February 2013 in Reproductive Medical Center, The Second Affiliated Hospital of WenZhou Medical University, WenZhou, China. The procedure was approved by the institutional ethical committee, and informed consents were obtained from all couples before study entry. Inclusion criteria were: (i) couples with their first IVF/intracytoplasmic sperm injection (ICSI) treatments; (ii) cancellation of fresh cycle transfer for the reason of increased risk for OHSS according to the classification of Golan et al. [5]; (iii) couples having both vitrified cleavage-stage embryos and vitrified blastocysts were candidates for frozen-thawed ET. Embryo freezing and thawing protocols The embryos were vitrified and thawed as described [6]. Then thawed embryos were scored, only high-quality cleavage-stage embryos and good-quality blastocysts, graded 3BB or better [7], were scheduled for FET.
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Frozen embryo transfer (FET) procedure For preparation of the endometrium, the patient was given 3 mg of estradiol valerate (Estrace; Roberts Pharmaceutical, Mississauga, Ontario, Canada) daily from day 2 to day 7 of menstrual cycle. After ultrasonography confirmed an endometrial thickness exceeding 8 mm, estradiol valerate was administered for another 3 more days and luteal support was initiated by 60 mg/d progesterone. Patients were scheduled for cleavage-stage ET or blastocyst transfer on the basis of their own voluntary. On day 3 or day 5 after initiation of progesterone administration, ET was performed under ultrasound guidance using Cook catheter. Luteal support was continued with intramuscular injection of 60 mg progesterone daily for 2 weeks.
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Outcome measures Pregnancy was diagnosed by serum human chorionic gonadotrophin (hCG) estimation 14 d after ET. Clinical pregnancy was confirmed by transvaginal ultrasound examination to assess the site, the number, and the viability of gestation 4 weeks after the positive pregnancy test. The primary outcome measures of the study were clinical pregnancy rate, implantation rate, multiple pregnancy rate, abortion rate and live birth rate. Statistical analysis Statistical analysis was performed using the Statistical Package for the Social Sciences, version 13.0 (SPSS Inc., Chicago, IL). Differences between groups were tested statistically by the use of 2 test for categorical data and the independent sample t-test for continuous variables. Data were considered to be statistically significant with p50.05.
Results This study covered the period from May 2012 to January 2013. A total of 162 couples both having vitrified cleavage-stage embryos and blastocysts were included, who refrained from fresh cycle transfer for reason of high risk for developing OHSS and then underwent elective cryopreservation of all their embryos. In the first frozen-thawed cycles, 162 couples were assigned on a voluntary basis to undergo cleavage-stage embryos transfer (N ¼ 70) or blastocysts transfer (N ¼ 92). There were no significant differences between the two groups with respect to patients’ demography and cycle characteristics, except for a significantly higher rank of mean number of cleavage-stage embryos transferred than blastocysts transferred (2.37 versus 2.11, p ¼ 0.02), as described in Table 1. As shown in Table 2, the numbers of transferred blastocysts were significantly lower than that of transferred cleavage-stage embryos. The present study showed that blastocysts transfer result in statistically higher clinical pregnancy (47.83 versus 31.43), implantation (31.44 versus 18.67), and live birth rates (40.21 versus 27.14), when compared with cleavage-stage transfer.
Gynecol Endocrinol, Early Online: 1–4
The multiple pregnancy rate (34.09 versus 36.36) and abortion rate (22.73 versus 13.64) were comparable in both groups.
Discussion Embryo cryopreservation provides a reasonable chance of achieving pregnancy in future artificial cycles [8] and extending embryo culture to day 5/6 forestalls unnecessary embryo freezing and increases this probabilities [9,10]. In this investigation, 162 women, who refrained from their fresh ET and electively cryopreserved all their embryos both at cleavage-stage and blastocyst-stage for high risk of developing OHSS, were allocated to the cleavage-stage ET or blastocysts transfer on the basis of patients’ voluntary in the first frozen cycles. The results showed that, although the mean number of transferred embryos in group A was significantly more than those in group B, the clinical pregnancy rates, implantation rates and live birth rates in group B were significantly higher than those in group A, and the multiple pregnancy rates in the both groups were comparable. When a patient undergoing IVF treatments is high risk for OHSS, preventive measures by temporal splitting ovarian stimulation and ET should be considered, which would not jeopardize the safety of the patient while still holding the opportunity for pregnancy [4,11]. After hCG administration, OHSS-risk patients often have high number of oocytes and subsequent embryos. In principle, to maximize the chance of pregnancy, any potential embryos, including those less promising, should be cryopreserved [12]. Nevertheless, a potential disadvantage of freezing-all policy is that some embryos may have very low or zero chance of implantation, freezing such embryos increases costs and may only help to raise patients’ hopes and expectations [12]. In addition, it is of note that OHSS-risk patients experiencing canceling fresh ET were very eager for a healthy birth as soon as possible. So the most effective process currently is to select the most viable embryos for cryopreservation and transfer in future frozen cycles. However, at present, there are no reliable instruments for distinguishing viable embryos and non-viable embryos. Advances in the dynamics of embryo culture allow us to culture embryos to blastocyst stage and permit selecting embryos Table 2. Clinical outcomes of frozen-thawed cycles. Group A (N ¼ 70)
Cycle outcomes Implantation rate (%) Clinical pregnancy rate (%) Multiple pregnancy rate (%) Number of singleton pregnancy Number of twin pregnancy Number of triplets pregnancy Abortion rate (%) Live birth rate (%)
Group B (N ¼ 92)
18.67 (31/166) 31.44 (61/194) 31.43 (22/70) 47.83 (44/92) 36.36 (8/22) 34.09 (15/44) 14 29 7 1 13.64 (3/22) 27.14 (19/70)
13 2 15.91 (7/44) 40.21 (37/92)
Table 1. The demographic data and cycle details of the infertile women. Patient characteristics Women age (years) Duration of infertility (years) Basal FSH (IU/L) Body mass index (kg/m2) Endometrial thickness on day of embryo transfer (mm) Mean number of embryo transferred
Group A (N ¼ 70)
Group B (N ¼ 92)
p Value
29.37 ± 3.55 3.59 ± 2.21 8.00 ± 1.81 21.85 ± 3.19 10.38 ± 1.62 2.37 ± 0.52
29.72 ± 3.48 4.14 ± 3.04 7.86 ± 1.85 21.23 ± 2.73 10.71 ± 1.87 2.11 ± 0.52
0.523 0.197 0.637 0.184 0.249 0.002
p Value S S NS
NS S
Outcomes in OHSS-risk women
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DOI: 10.3109/09513590.2015.1062858
with increased probability of implantation [13–15]. Indeed, positive results of blastocyst transfer have been reported in good prognosis patients (young age, good ovarian response). In a prospective study of women under 36 years with their first or second IVF attempts, transfer of single blastocyst resulted in higher pregnancy rate than transfer of single cleavage-stage embryo [16]. Also, a prospective randomized controlled trial, with each patient having at least four morphologically good-quality embryos on day 3, demonstrated significantly higher ongoing pregnancy rate and live birth rate was achieved from transferring two blastocysts, when compared with transferring two cleavagestage embryos [17]. Meanwhile, another study suggested that delaying ET to day 5 may increase the probability of pregnancy in women, who had oestradiol 43000 pg/ml on day of hCG administration and four or more good-quality embryos on day 3 [18]. Similar to the former three studies, the subjects included in this study were high risk for OHSS and often had large number of small follicles, which is an indication for good prognosis patients. And the present study also indicated that, in the first frozenthawed ET, OHSS-risk patients could benefit from blastocysts transfer when compared with cleavage-stage embryos transfer. The discrepancy between this study and the former three studies lies in: both cleavage ETs and blastocyst transfers in the former three studies were performed in fresh cycles, and generally accompanied by high oestradiol levels [16–18], which might have adverse effects on endometrium receptivity and bias the cycle outcomes [19,20]; while the ETs in this study were all performed in frozen-thawed cycles, the endometrium microenvironments were similar to those in natural cycles, without the interference of high oestradiol levels in fresh cycle, thus the results from this study may be more revealing for the advantages of blastocyst transfer. In present study, the mean number of transferred cleavagestage embryos was significantly more than that in blastocyst transfer, while the pregnancy rate in blastocyst transfer was significantly higher than that in cleavage-stage ET. The main reason for higher success rates with blastocyst transfer might relate to the embryo selection process. It has been shown that 59% of top-quality embryos on day 3 were genetically abnormal, whereas only 35% of top-quality blastocysts had genetic abnormalities [9]. Even when genetic abnormalities have not prevented development to the blastocyst stage and there are still some chromosomally abnormal blastocysts, the proportion of genetic abnormalities in blastocysts would be lower than what is observed on cleavage-stage embryos. Thus, the blastocyst transfer will carry a lower risk of being aneuploid compared with cleavage-stage embryos transfer, thereby increase a patient’s chances of achieving an ongoing pregnancy. Another explanation for the discrepancy is that the developmental stage of transferred cleavage-stage embryos is not synchronized to the counterpart of reproductive tract [7]. As the oviduct and uterus provide different nutritional environments for the developing embryo, the transfer of cleavage-stage embryo to uterine cavity might be involved in metabolic stress that may impair embryo viability [9,21]. Blastocyst transfer would be identical to the time of natural pregnancy and make it possible to minimize or delay embryos exposure to such an environment. Moreover, high frequency of uterine contractions following hCG administration has been reported to relate to low pregnancy rates [22], whereas the frequency decreases significantly over time [23]. Therefore, transfer of blastocysts might mirror the risk of embryo expulsion from the uterus. In order to maintain an acceptable pregnancy rate in IVF, transferring multiple embryos has been performed. On the other side, it also increases risks for multiple births complications, including the increased incidence of maternal, perinatal and
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neonatal morbidity and mortality [24]. It has been concluded that minimizing the number of transferred embryos is the best way to prevent these side effects. Actually, a retrospective analysis with selected cases showed that, although fewer number of blastocysts were transferred compared with cleavage-stage ET, there was no significant difference between the two groups in terms of higher order pregnancy rate [25]. Similar to the former study, the results in this investigation showed, although with fewer replaced blastocysts, the multiple pregnancy rates in two groups (cleavage group ¼ 36.36 versus blastocyst group ¼ 34.09) were still comparable and high, which is a reflection of higher implantation rate in the blastocyst group. This will condense to limit the transfer of two or lesser blastocysts to reduce the chance for a multiple gestation without compromising the clinical pregnancy rate. In general, the observed results in OHSS-risk population allow us to take a position in favor of blastocyst transfer, thus pregnancy and live birth could be achieved with fewer transferred embryos and in a shorter time frame. The further work is to reduce the incidence of multiple births with fewer transferred blastocysts while maintaining a reasonable pregnancy.
Declaration of interest The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the article. This study was supported by the Program for Zhejiang Leading Team of S&T Innovation, P.R. China (2011R50013) and grants from Wenzhou Municipal Science and Technology Fund of China (Y20100205).
References 1. Kolibianakis EM, Collins J, Tarlatzis BC, et al. Among patients treated for IVF with gonadotrophins and GnRH analogues, is the probability of live birth dependent on the type of analogue used? A systematic review and meta-analysis. Hum Reprod Update 2006; 12:651–71. 2. Huddleston HG, Racowsky C, Jackson KV, et al. Coasting versus cryopreservation of all embryos for prevention of ovarian hyperstimulation syndrome in in vitro fertilization. Fertil Steril 2008;90: 1259–62. 3. John T, Queenan JR. Embryo freezing to prevent ovarian hyperstimulation syndrome. Mol Cell Endocrinol 2000;169:79–83. 4. Manzanares MA, Gomez-Palomares JL, Ricciarelli E, Hernandez ER. Triggering ovulation with gonadotropin-releasing hormone agonist in in vitro fertilization patients with polycystic ovaries does not cause ovarian hyperstimulation syndrome despite very high estradiol levels. Fertil Steril 2000;93:1215–19. 5. Golan A, Ron-el R, Herman A, et al. Ovarian hyperstimulation syndrome: an update review. Obstetr Gynecol Surv 1989;44:430–40. 6. Tong GQ, Cao SR, Wu X, et al. Clinical outcome of fresh and vitrified-warmed blastocyst and cleavage-stage embryo transfers in ethnic Chinese ART patients. J Ovarian Res 2012;5:271–7. 7. Gardner DK, Vella P, Lane M, et al. Culture and transfer of human blastocysts increases implantation rates and reduces the need for multiple embryo transfers. Fertil Steril 1998;69:84–8. 8. Tiitinen A, Halttunen M, Harkki P, et al. Elective single embryo transfer: the value of cryopreservation. Hum Reprod 2001;16: 1140–4. 9. Magli MC, Jones GM, Gras L, et al. Chromosome mosaicism in day 3 aneuploid embryos that develop to morphologically normal blastocysts in vitro. Hum Reprod 2000;15:1781–6. 10. Gardner DK, Schoolcraft WB, Wagley L, et al. A prospective randomized trial of blastocyst culture and transfer in in-vitro fertilization. Hum Reprod 1998;13:3434–40. 11. Griesinger G, von Otte S, Schroer A, et al. Elective cryopreservation of all pronuclear oocytes after GnRH agonist triggering of final oocyte maturation in patients at risk of developing OHSS: a prospective, observational proof-of concept study. Hum Reprod 2007;22:1348–52. 12. Bechoua S, Astruc K, Thouvenot S, et al. How to demonstrate that eSET does not compromise the likelihood of having a baby? Hum Reprod 2009;24:3073–81.
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13. Noyes N, Reh A, McCaffrey C, et al. Impact of developmental stage at cryopreservation and transfer on clinical outcome of frozen embryo cycles. Reprod BioMed Online 2009;19: 9–15. 14. Jones HW. Multiple births: how are we doing? Fertil Steril 2003;79: 17–21. 15. Jones GM, Trouson AO, Lolatgi N, Wood C. Factors affecting the success of human blastocyst development and pregnancy following in vitro fertilization and embryo transfer. Fertil Steril 1998;70: 1022–9. 16. Papanikolaou EG, Camus M, Kolibianakis EM, et al. In vitro fertilization with single blastocyst-stage versus single cleavage-stage embryos. N Engl J Med 2006;354:1139–46. 17. Papanikolaou EG, D’haeseleer E, Verheyen G, et al. Live birth rate is significantly higher after blastocyst transfer than after cleavagestage embryo transfer when at least four embryos are available on day 3 of embryo culture: a randomized prospective study. Hum Reprod 2005;20:3198–203. 18. Elgindy EA, Abou-Setta AM, Mostaf MI. Blastocyst-stage versus cleavage-stage embryo transfer in women with high oestradiol concentrations: randomized controlled trial. Reprod BioMed Online 2011;23:789–98.
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19. Chen CH, Zhang X, Barnes R, et al. Relationship between peak serum oestradiol levels and treatment outcome in in vitro fertilization cycles after embryo transfer on day 3 or day 5. Fertil Steril 2003;80:75–9. 20. Valbuena D, Martin J, de Pablo JL, et al. Increasing levels of oestradiol are deleterious to embryonic implantation because they directly affect the embryo. Fertil Steril 2001;76:962–8. 21. Papanikolaou EG, Camus M, Fatemi HM, et al. Early pregnancy loss is significantly higher after day 3 single embryo transfer than after day 5 single blastocyst transfer in GnRH antagonist stimulated IVF cycles. Reprod BioMed Online 2006;12:60–5. 22. Fanchin R, Righini C, Olivennes F, et al. Uterine contractions at the time of embryo transfer alter pregnancy rates after in-vitro fertilization. Hum Reprod 1998;13:1968–74. 23. Fanchin R, Ayoubi JM, Righini C, et al. Uterine contractility decreases at the time of blastocyst transfers. Hum Reprod 2001;16: 1115–19. 24. The ESHRE Capri Workshop Group. Multiple gestation pregnancy. Hum Reprod 2000;15:1856–64. 25. Mangalraj AM, Muthukumar K, Aleyamma TK, et al. Blastocyst stage transfer vs cleavage stage embryo transfer. J Hum Reprod Sci 2009;2:23–7.
Gynecological Endocrinology Publication details, including instructions for authors and subscription information: http://www.tandfonline.com/loi/igye20
Blastocyst-stage versus cleavage-stage embryo transfer in the first frozen cycles of OHSS-risk patients who deferred from fresh embryo transfer a
a
b
a
a
a
Hua Chen , Jie-Qiang Lv , Xin-Mei Wu , Yu Xiao , Hai-Tao Xi , Chun-Fang Zhu , Jian-Ying a
a
a
Huang , Fan Zhang & Hong-Shan Ge a
Reproductive Medicine Center, The 2nd Affiliated Hospital & Yuying Children’s Hospital of WenZhou Medical University, WenZhou, China and b
Department of Clinical Laboratory, The 2nd Affiliated Hospital & Yuying Children’s Hospital of WenZhou Medical University, WenZhou, China Published online: 20 Jul 2015.
Click for updates To cite this article: Hua Chen, Jie-Qiang Lv, Xin-Mei Wu, Yu Xiao, Hai-Tao Xi, Chun-Fang Zhu, Jian-Ying Huang, Fan Zhang & Hong-Shan Ge (2015): Blastocyst-stage versus cleavage-stage embryo transfer in the first frozen cycles of OHSS-risk patients who deferred from fresh embryo transfer, Gynecological Endocrinology To link to this article: http://dx.doi.org/10.3109/09513590.2015.1062858
PLEASE SCROLL DOWN FOR ARTICLE Taylor & Francis makes every effort to ensure the accuracy of all the information (the “Content”) contained in the publications on our platform. However, Taylor & Francis, our agents, and our licensors make no representations or warranties whatsoever as to the accuracy, completeness, or suitability for any purpose of the Content. Any opinions and views expressed in this publication are the opinions and views of the authors, and are not the views of or endorsed by Taylor & Francis. The accuracy of the Content should not be relied upon and should be independently verified with primary sources of information. Taylor and Francis shall not be liable for any losses, actions, claims, proceedings, demands, costs, expenses, damages, and other liabilities whatsoever or howsoever caused arising directly or indirectly in connection with, in relation to or arising out of the use of the Content. This article may be used for research, teaching, and private study purposes. Any substantial or systematic reproduction, redistribution, reselling, loan, sub-licensing, systematic supply, or distribution in any form to anyone is expressly forbidden. Terms & Conditions of access and use can be found at http:// www.tandfonline.com/page/terms-and-conditions
http://informahealthcare.com/gye ISSN: 0951-3590 (print), 1473-0766 (electronic) Gynecol Endocrinol, Early Online: 1–4 ! 2015 Informa UK Ltd. DOI: 10.3109/09513590.2015.1062858
ORIGINAL ARTICLE
Blastocyst-stage versus cleavage-stage embryo transfer in the first frozen cycles of OHSS-risk patients who deferred from fresh embryo transfer Hua Chen1, Jie-Qiang Lv1, Xin-Mei Wu2, Yu Xiao1, Hai-Tao Xi1, Chun-Fang Zhu1, Jian-Ying Huang1, Fan Zhang1, and Hong-Shan Ge1 Downloaded by [Nanyang Technological University] at 06:57 27 August 2015
1
Reproductive Medicine Center, The 2nd Affiliated Hospital & Yuying Children’s Hospital of WenZhou Medical University, WenZhou, China and Department of Clinical Laboratory, The 2nd Affiliated Hospital & Yuying Children’s Hospital of WenZhou Medical University, WenZhou, China
2
Abstract
Keywords
Elective cryopreservation of all embryos has been the most effective means to avoid developing ovarian hyperstimulation syndrome (OHSS). However, it is still unknown which stage is optimal for freezing and transferring into uterus in OHSS-risk patients. This study was undertaken to evaluate whether OHSS-risk patients could benefit from transferring blastocysts. A total of 162 women were allocated to cleavage-stage embryo transfer (ET) (group A ¼ 70) and blastocysts transfer (group B ¼ 92) on the basis of patients’ voluntary in their first frozen cycles. Although the mean number of transferred embryos in group A was significantly more than those in group B (2.37 ± 0.52 versus 2.11 ± 0.52, p50.05), the clinical pregnancy rates, implantation rates and live birth rates in group B were significantly higher than those in group A (47.83% versus 31.43%, p50.05; 31.44% versus 18.67%, p50.05; 40.21% versus 27.14%, p50.05), and the multiple pregnancy rates in both groups were comparable (34.09% versus 36.36%, p40.05). The observed results in OHSS-risk population allow us to take a position in favor of blastocyst transfer, thus pregnancy and live birth could be achieved with fewer ETs and in a shorter time frame.
Blastocyst transfer, cleavage-stage embryo, first frozen cycle, OHSS-risk patients
Introduction Ovarian hyperstimulation syndrome (OHSS), with the incidence of 5–10%, is the most frequent serious complication from ovarian stimulation in in vitro fertilization (IVF) [1]. The mild form is of only minor relevance, while its severe form is life-threatening. Given the iatrogenic nature of this condition, it is particularly important to minimize the risk of developing OHSS in women receiving fertility treatment. Several strategies have been described to reduce the incidence and severity of OHSS in a high-risk population. So far, the strategy refraining from fresh embryo transfer (ET) and elective cryopreservation of all embryos for future frozen-thaw transfer, allowing a reasonable chance of achieving pregnancy, could be the most effective means to resolve the challenge. Really, avoiding fresh ET in OHSS-risk patients has been confirmed in several reports, and acceptable pregnancy was achieved with frozen embryo transfer (FET) [2–4]. However, Are cleavage-stage morphological parameters reliable enough to determine embryo viability, or is it better to culture embryos to blastocyst? Which stage is optimal for freezing and transferring into uterus remains a matter of debate. This study aims to compare the efficacy of transferring thawed embryos at the cleavage-stage or at blastocyst-stage in the first Address for correspondence: Hong-Shan Ge, Reproductive Center, The 2nd Affliated Hospital & Yuying Children’s Hospital of Wenzhou Medical University, Wenzhou, China. Tel: +86-577-88002612. Fax: +86577-88002622. E-mail: [email protected]
History Received 31 July 2014 Accepted 12 June 2015 Published online 20 July 2015
frozen-thawed cycles of patients who deferred from fresh ET because of high risk for OHSS, and to suggest a practice model of elective cryopreservation of more promising embryos, which would result in better clinical outcomes with fewer ETs and in shorter time frame.
Methods Patients population This prospective study was conducted from May 2012 to February 2013 in Reproductive Medical Center, The Second Affiliated Hospital of WenZhou Medical University, WenZhou, China. The procedure was approved by the institutional ethical committee, and informed consents were obtained from all couples before study entry. Inclusion criteria were: (i) couples with their first IVF/intracytoplasmic sperm injection (ICSI) treatments; (ii) cancellation of fresh cycle transfer for the reason of increased risk for OHSS according to the classification of Golan et al. [5]; (iii) couples having both vitrified cleavage-stage embryos and vitrified blastocysts were candidates for frozen-thawed ET. Embryo freezing and thawing protocols The embryos were vitrified and thawed as described [6]. Then thawed embryos were scored, only high-quality cleavage-stage embryos and good-quality blastocysts, graded 3BB or better [7], were scheduled for FET.
2
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Frozen embryo transfer (FET) procedure For preparation of the endometrium, the patient was given 3 mg of estradiol valerate (Estrace; Roberts Pharmaceutical, Mississauga, Ontario, Canada) daily from day 2 to day 7 of menstrual cycle. After ultrasonography confirmed an endometrial thickness exceeding 8 mm, estradiol valerate was administered for another 3 more days and luteal support was initiated by 60 mg/d progesterone. Patients were scheduled for cleavage-stage ET or blastocyst transfer on the basis of their own voluntary. On day 3 or day 5 after initiation of progesterone administration, ET was performed under ultrasound guidance using Cook catheter. Luteal support was continued with intramuscular injection of 60 mg progesterone daily for 2 weeks.
Downloaded by [Nanyang Technological University] at 06:57 27 August 2015
Outcome measures Pregnancy was diagnosed by serum human chorionic gonadotrophin (hCG) estimation 14 d after ET. Clinical pregnancy was confirmed by transvaginal ultrasound examination to assess the site, the number, and the viability of gestation 4 weeks after the positive pregnancy test. The primary outcome measures of the study were clinical pregnancy rate, implantation rate, multiple pregnancy rate, abortion rate and live birth rate. Statistical analysis Statistical analysis was performed using the Statistical Package for the Social Sciences, version 13.0 (SPSS Inc., Chicago, IL). Differences between groups were tested statistically by the use of 2 test for categorical data and the independent sample t-test for continuous variables. Data were considered to be statistically significant with p50.05.
Results This study covered the period from May 2012 to January 2013. A total of 162 couples both having vitrified cleavage-stage embryos and blastocysts were included, who refrained from fresh cycle transfer for reason of high risk for developing OHSS and then underwent elective cryopreservation of all their embryos. In the first frozen-thawed cycles, 162 couples were assigned on a voluntary basis to undergo cleavage-stage embryos transfer (N ¼ 70) or blastocysts transfer (N ¼ 92). There were no significant differences between the two groups with respect to patients’ demography and cycle characteristics, except for a significantly higher rank of mean number of cleavage-stage embryos transferred than blastocysts transferred (2.37 versus 2.11, p ¼ 0.02), as described in Table 1. As shown in Table 2, the numbers of transferred blastocysts were significantly lower than that of transferred cleavage-stage embryos. The present study showed that blastocysts transfer result in statistically higher clinical pregnancy (47.83 versus 31.43), implantation (31.44 versus 18.67), and live birth rates (40.21 versus 27.14), when compared with cleavage-stage transfer.
Gynecol Endocrinol, Early Online: 1–4
The multiple pregnancy rate (34.09 versus 36.36) and abortion rate (22.73 versus 13.64) were comparable in both groups.
Discussion Embryo cryopreservation provides a reasonable chance of achieving pregnancy in future artificial cycles [8] and extending embryo culture to day 5/6 forestalls unnecessary embryo freezing and increases this probabilities [9,10]. In this investigation, 162 women, who refrained from their fresh ET and electively cryopreserved all their embryos both at cleavage-stage and blastocyst-stage for high risk of developing OHSS, were allocated to the cleavage-stage ET or blastocysts transfer on the basis of patients’ voluntary in the first frozen cycles. The results showed that, although the mean number of transferred embryos in group A was significantly more than those in group B, the clinical pregnancy rates, implantation rates and live birth rates in group B were significantly higher than those in group A, and the multiple pregnancy rates in the both groups were comparable. When a patient undergoing IVF treatments is high risk for OHSS, preventive measures by temporal splitting ovarian stimulation and ET should be considered, which would not jeopardize the safety of the patient while still holding the opportunity for pregnancy [4,11]. After hCG administration, OHSS-risk patients often have high number of oocytes and subsequent embryos. In principle, to maximize the chance of pregnancy, any potential embryos, including those less promising, should be cryopreserved [12]. Nevertheless, a potential disadvantage of freezing-all policy is that some embryos may have very low or zero chance of implantation, freezing such embryos increases costs and may only help to raise patients’ hopes and expectations [12]. In addition, it is of note that OHSS-risk patients experiencing canceling fresh ET were very eager for a healthy birth as soon as possible. So the most effective process currently is to select the most viable embryos for cryopreservation and transfer in future frozen cycles. However, at present, there are no reliable instruments for distinguishing viable embryos and non-viable embryos. Advances in the dynamics of embryo culture allow us to culture embryos to blastocyst stage and permit selecting embryos Table 2. Clinical outcomes of frozen-thawed cycles. Group A (N ¼ 70)
Cycle outcomes Implantation rate (%) Clinical pregnancy rate (%) Multiple pregnancy rate (%) Number of singleton pregnancy Number of twin pregnancy Number of triplets pregnancy Abortion rate (%) Live birth rate (%)
Group B (N ¼ 92)
18.67 (31/166) 31.44 (61/194) 31.43 (22/70) 47.83 (44/92) 36.36 (8/22) 34.09 (15/44) 14 29 7 1 13.64 (3/22) 27.14 (19/70)
13 2 15.91 (7/44) 40.21 (37/92)
Table 1. The demographic data and cycle details of the infertile women. Patient characteristics Women age (years) Duration of infertility (years) Basal FSH (IU/L) Body mass index (kg/m2) Endometrial thickness on day of embryo transfer (mm) Mean number of embryo transferred
Group A (N ¼ 70)
Group B (N ¼ 92)
p Value
29.37 ± 3.55 3.59 ± 2.21 8.00 ± 1.81 21.85 ± 3.19 10.38 ± 1.62 2.37 ± 0.52
29.72 ± 3.48 4.14 ± 3.04 7.86 ± 1.85 21.23 ± 2.73 10.71 ± 1.87 2.11 ± 0.52
0.523 0.197 0.637 0.184 0.249 0.002
p Value S S NS
NS S
Outcomes in OHSS-risk women
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DOI: 10.3109/09513590.2015.1062858
with increased probability of implantation [13–15]. Indeed, positive results of blastocyst transfer have been reported in good prognosis patients (young age, good ovarian response). In a prospective study of women under 36 years with their first or second IVF attempts, transfer of single blastocyst resulted in higher pregnancy rate than transfer of single cleavage-stage embryo [16]. Also, a prospective randomized controlled trial, with each patient having at least four morphologically good-quality embryos on day 3, demonstrated significantly higher ongoing pregnancy rate and live birth rate was achieved from transferring two blastocysts, when compared with transferring two cleavagestage embryos [17]. Meanwhile, another study suggested that delaying ET to day 5 may increase the probability of pregnancy in women, who had oestradiol 43000 pg/ml on day of hCG administration and four or more good-quality embryos on day 3 [18]. Similar to the former three studies, the subjects included in this study were high risk for OHSS and often had large number of small follicles, which is an indication for good prognosis patients. And the present study also indicated that, in the first frozenthawed ET, OHSS-risk patients could benefit from blastocysts transfer when compared with cleavage-stage embryos transfer. The discrepancy between this study and the former three studies lies in: both cleavage ETs and blastocyst transfers in the former three studies were performed in fresh cycles, and generally accompanied by high oestradiol levels [16–18], which might have adverse effects on endometrium receptivity and bias the cycle outcomes [19,20]; while the ETs in this study were all performed in frozen-thawed cycles, the endometrium microenvironments were similar to those in natural cycles, without the interference of high oestradiol levels in fresh cycle, thus the results from this study may be more revealing for the advantages of blastocyst transfer. In present study, the mean number of transferred cleavagestage embryos was significantly more than that in blastocyst transfer, while the pregnancy rate in blastocyst transfer was significantly higher than that in cleavage-stage ET. The main reason for higher success rates with blastocyst transfer might relate to the embryo selection process. It has been shown that 59% of top-quality embryos on day 3 were genetically abnormal, whereas only 35% of top-quality blastocysts had genetic abnormalities [9]. Even when genetic abnormalities have not prevented development to the blastocyst stage and there are still some chromosomally abnormal blastocysts, the proportion of genetic abnormalities in blastocysts would be lower than what is observed on cleavage-stage embryos. Thus, the blastocyst transfer will carry a lower risk of being aneuploid compared with cleavage-stage embryos transfer, thereby increase a patient’s chances of achieving an ongoing pregnancy. Another explanation for the discrepancy is that the developmental stage of transferred cleavage-stage embryos is not synchronized to the counterpart of reproductive tract [7]. As the oviduct and uterus provide different nutritional environments for the developing embryo, the transfer of cleavage-stage embryo to uterine cavity might be involved in metabolic stress that may impair embryo viability [9,21]. Blastocyst transfer would be identical to the time of natural pregnancy and make it possible to minimize or delay embryos exposure to such an environment. Moreover, high frequency of uterine contractions following hCG administration has been reported to relate to low pregnancy rates [22], whereas the frequency decreases significantly over time [23]. Therefore, transfer of blastocysts might mirror the risk of embryo expulsion from the uterus. In order to maintain an acceptable pregnancy rate in IVF, transferring multiple embryos has been performed. On the other side, it also increases risks for multiple births complications, including the increased incidence of maternal, perinatal and
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neonatal morbidity and mortality [24]. It has been concluded that minimizing the number of transferred embryos is the best way to prevent these side effects. Actually, a retrospective analysis with selected cases showed that, although fewer number of blastocysts were transferred compared with cleavage-stage ET, there was no significant difference between the two groups in terms of higher order pregnancy rate [25]. Similar to the former study, the results in this investigation showed, although with fewer replaced blastocysts, the multiple pregnancy rates in two groups (cleavage group ¼ 36.36 versus blastocyst group ¼ 34.09) were still comparable and high, which is a reflection of higher implantation rate in the blastocyst group. This will condense to limit the transfer of two or lesser blastocysts to reduce the chance for a multiple gestation without compromising the clinical pregnancy rate. In general, the observed results in OHSS-risk population allow us to take a position in favor of blastocyst transfer, thus pregnancy and live birth could be achieved with fewer transferred embryos and in a shorter time frame. The further work is to reduce the incidence of multiple births with fewer transferred blastocysts while maintaining a reasonable pregnancy.
Declaration of interest The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the article. This study was supported by the Program for Zhejiang Leading Team of S&T Innovation, P.R. China (2011R50013) and grants from Wenzhou Municipal Science and Technology Fund of China (Y20100205).
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