2013 Sep.; 24(3):

Transcription

1 Journal of Reproduction & Contraception doi: /j.issn Sep.; 24(3): Reducing the Trigger Dose of Human Chorionic Gonadotrophin Does Not Affect Final Oocyte Maturation and Subsequently Pregnancy Outcome of Frozen-thawed Embryo Transfer Yun WANG *, Yong-lun FU *, Shao-feng CAO, Qiu-ju CHEN, Song-guo XUE, Qi-feng LYU, Yan-ping KUANG Department of Assisted Reproductive, Shanghai Ninth People s Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai , China Objective To compare the efficacy of human chorionic gonadotrophin (hcg) at reduced doses of IU and IU for moderate or high responders with the dose of IU in term of inducing final oocyte maturation for IVF/ICSI and the subsequent pregnancy outcome in frozen-thawed embryo transfer (FET). Methods In the retrospective cohort study, patients undergoing IVF/ICSI with moderate or high response were recruited and classified into three groups according to the trigger dose of hcg: IU (group A, n=), IU (group B, n=) and IU (group C, n=). The main outcome was the proportion of mature oocytes retrieved, fertilization rates, clinical pregnancy rates, cumulative pregnancy rates and incidence of ovarian hyperstimulation syndrome (OHSS). Results No evidence of statistically difference was found in the proportion of mature oocytes retrieved (89.92%, 91.40%, 90.20%, respectively) and fertilization rate (79.8%, 80.07%, 80.51%, respectively) among groups A, B and C. Serum E2 level on the day of hcg injection, the number of mature oocytes retrieved and good-quality embryos in group A were significantly higher than those in group B and group C. Clinical pregnancy rates per transfer cycle (45.95%, 43.97% and 44.25%), ongoing pregnancy rates (43.17%, 40.91% and 42.53%), implantation rates (30.74%, 27.78% and 29.86%) and cumulative pregnancy rates per patient (58.31%, 53.6% and 54.85%) This study was supported by National Natural Science Foundation of China (No ) and Natural Science Foundation of Shanghai of China (No ) Corresponding author: Qi-feng LYU; Tel: *5538; Fax: ; lyuqifeng@126.com Yan-ping KUANG; Kuangyanp@126.com *: These two authors contributed equally to this paper 151

2 were comparable among groups A, B and C. The incidence of OHSS in groups A, B and C (0%, 0.14% and 0.28%) was low, with no significant difference. Conclusion A reduced hcg dose of IU for moderate or high responders leads to similar efficacy compared with a dose of IU in inducing oocyte maturation without adversely affecting the pregnancy outcome meanwhile eliminating the risk of OHSS. Key words: human chorionic gonadotropin (hcg); controlled ovarian hyperstimulation (COH); ovarian hyperstimulation syndrome (OHSS); frozen-thawed embryo transfer (FET); cumulative pregnancy rate (CPR) The use of exogenous human chorionic gonadotropin (hcg) to mimic the ovulation inducing LH surge is of great importance in the field of reproductive medicine. Due to its high LH receptor affinity and low disappearance rate, this exogenous hcg causes a nonphysiological high and long lasting stimulation of the luteal body [1,2]. The direct consequence of an exaggerated follicular response to controlled ovarian stimulation (COH) in the presence of hcg is the initiation of ovarian hyperstimulation syndrome (OHSS) [3]. In most cases, OHSS is self-limiting and resolves spontaneously within several days, however, moderate or severe OHSS can cause significantly morbidity and be fatal in its critical stage [4]. There is no existing data on the optimal dose requirements of hcg for final oocyte maturation. Under the examination of microscope, the occurrence of the first polar body is a hallmark of oocyte maturation. The maturation of ooplasm plays an important role in the process of fertilization and early development of embryos. Sperm adherence and penetration are highly related to the maturation of the ooplasm [5]. Doses of hcg as low as IU [6] have been shown to effectively trigger oocyte maturation in assisted reproductive technology (ART) without adversely affecting cycle outcome; IU was ineffective [7]. Doses of hcg as low as IU have been shown to be effective in patients with PCOS [8]. The reducing dose of hcg was proved to be able to prevent the development of OHSS [8] or unable to prevent OHSS in high-risk women [6]. In recent years, we attempted to identify the optimal effective doses of hcg trigger and found that adequate oocyte maturation could be obtained with the dose of IU or IU when administered to moderate or high responders. We used a strategy of lower dose of hcg (2 000 IU or IU) in combination with cryopreservation of all embryos for moderate and high responders to prevent the developing of OHSS. Therefore, the retrospective study was aimed to assess whether the lower trigger doses of hcg (2 000 IU or IU) equally induce final oocyte maturation and subsequent pregnancy outcome in frozen-thawed embryo transfer (FET) cycles compared with the dose of IU. 152

3 Materials & Methods Study design and participants This was a retrospectively observational study of patients undergoing IVF/ICSI practice. The consecutive patients who underwent induced ovulation using long protocol and subsequent FETs from February 1, 2011 to July 31, 2012 were collected and grouped according to the dose of hcg IU (group A), IU (group B) and IU (group C) for triggering ovulation. The inclusion criteria was: 1) basal follicle-stimulating hormone (bfsh)<10 miu/ml with body mass index (BMI) 25 kg/m 2 ; 2) serum estradiol (E2) pg/ml and no less than 10 follicles with 10 mm in diameter on the day of hcg administration; 3) adequate sperm for IVF or ICSI. Study process Ovarian stimulation and embryo culture Ovarian stimulation was facilitated by the long protocol with 50 μg of Decapeptyl (Ferring International Center SA, Germany) given SC starting on day 21 of the preceding cycle. hmg (Anhui Fengyuan Pharmaceutical Co., China) was given at a dose of IU/d from day 3 of menstruation and Decapeptyl was continued until the day of hcg administration. The dose of hmg was adjusted according to oestradiol concentrations and ovarian response. hcg (Guangdong Lizhu Pharmaceutical Co., China) was used to trigger ovulation when at least one follicle was more than 20 mm or two follicles were more than 18 mm in diameter. Oocyte retrieval was carried out h after the hcg triggering. Fertilization was carried out in-vitro either by conventional insemination or ICSI depending on the semen parameters and previous fertilization history. Embryos were examined for the number/ regularity of blastomeres and the degree of fragmentation, and graded according to the criteria of Cummins [9]. OHSS cases were classified according to previously published classification system [10]. All good-quality embryos were frozen on the third day of oocyte retrieval. The nongood-quality embryos were thus placed for further extended culture until blastocyst stage and only good morphology blastocysts were frozen. Procedure of freezing-thawing of cleavagestage embryos and blastocysts has been described previously [11]. Thawed embryos were classified as either fully intact (100% cells survived), partially damaged ( 50% cells survived) or degenerated (<50% cells survived) [12]. Only intact and partially damaged embryos were considered as survival and would be transferred. Endometrial preparation and FET Patients were prepared for FET with daily oral administration of 8 mg estradiol valerate (Abott Biological B.V, Netherland) started from day 3 to attain the criteria of endometrial thickness 8 mm and tripleline pattern on ultrasound scans. At that time, patients were 153

4 given 0.4 g progesterone (Laboratoires Besins-Iscovesco, France) intravaginal daily and embryo transfer was performed 3 d later under abdominal ultrasound guidance. Oral estradiol and progesterone were continued until documentation of fetal heart activity by ultrasonography [13]. Outcome measures The primary outcome measure was the proportion of mature oocytes (metaphase II oocyte) retrieved per patient following hcg administration. Percentage of oocytes retrieved=the number of oocytes retrieved/the number of follicles punctured 100%, percentage of mature oocytes retrieved=the number of mature oocytes retrieved/the number of oocytes retrieved 100%, fertilization rate=the number of fertilized oocytes/the number of mature oocytes retrieved 100%. The secondary outcome included the fertilization rate, the clinical pregnancy rate per transfer cycle and the cumulative pregnancy rate per patient. Clinical pregnancy was considered as the presence of a gestational sac with fetal heart activity, as assessed by ultrasound at 7 weeks of gestation. Ongoing pregnancy was defined as pregnancy proceeding beyond the 12th gestational week. Cumulative pregnancy was defined as the total number of pregnancy using multiple FETs. Statistical analysis Data were expressed as mean SD (x s) or percentage (%). Statistical analysis was performed by SPSS16.0. χ 2 test was used for categorical comparisons or Fisher s exact tests as appropriate. One-way ANOVA was used for continuous variables. The significant difference was considered at P value less than Results A total of patients had completed the oocyte retrieval cycles and were analyzed. A total of FET cycles were performed during the research period. There were no significant differences regarding demographic characteristics among the three groups (Table 1). The clinical and embryological characteristics of the population are demonstrated in Table 2. The duration of stimulation was similar among the three groups (P>0.05). Total dose of gonadotropin consumption in group A was significantly lower than that in group C (P<0.05). Serum E2 level on the day of hcg administration, the number of oocytes retrieved, the number of mature oocytes in group A were higher than those in group B meanwhile those indexes in group B were higher than those in group C (P<0.05). No significant difference was found in the proportion of oocytes retrieved, the mature oocyte rate and the fertilization rate among the three groups (P>0.05). The embryo cryosurvival rate was about 98%. There was no significant difference in the number of embryos transferred and the pregnancy outcome of the FET cycles (Table 3). The clinical pregnancy rate per transfer was 154

5 Table 1 Patients characteristics (x s or %) Parameter Group A Group B Group C n Age (year) BMI (kg/m 2 ) Day 3 FSH (IU/ml) Duration of infertility (a) Cause of infertility (%) Tubal factor Male factor Ovulatory factor Endometriosis Unexplained 67.5 (487/) 16.2 (117/) 8.9 (64/) 3.0 (22/) 4.4 (32/) 66.6 (481/) 14.7 (106/) 9.4 (68/) 3.3 (24/) 6.0 (43/) 69.4 (501/) 14.5 (105/) 9.0 (65/) 2.5 (18/) 4.6 (33/) Table 2 Cycle characteristics (x s or %) Parameter Group A Group B Group C n Duration of stimulation (d) Total Gn consumption (IU) * E2 on the day of hcg injection (pg/ml) *# * No. of oocytes retrieved (n) *# * Percentage of oocytes retrieved (%) No. of mature oocytes retrieved (n) *# * Percentage of mature oocytes (%) ICSI performance (%) (123/) (115/) (110/) Fertilization rate (%) No. of embryos vitrified (n) *# * No. of embryos warmed per transfer cycle (n) Patients without vitrified embryos (%) Rate of moderate and severe OHSS (%) *: P<0.05, compared with group C #: P<0.05, compared with group B 3.19 (23/) 0.00 (0/) 2.90 (21/) 0.14 (1/) 3.60 (26/) 0.28 (2/) Table 3 Treatment outcomes Parameter Group A Group B Group C Clinical PR per transfer (%) Ongoing PR per transfer (%) Multiple pregnancy rate (%) Implantation rate (%) Cumulative PR per patient (%) PR: pregnancy rate (448/975) (421/975) (114/421) (535/1 740) (421/) (416/946) (387/946) (112/387) (499/1 796) (387/) (412/931) (396/931) (105/396) (501/1 678) (396/) 155

6 45.95% in group A, 43.97% in group B and 44.25% in group C, with no significant difference (P>0.05). The cumulative pregnancy rates per patient were 58.31% in group A, 53.60% in group B and 54.85% in group C, without significant differences (P>0.05). The incidence of moderate and severe OHSS is low in the study and no difference was found among groups A, B and C (0%, 0.14%, 0.28%, respectively, P>0.05). Only 3 cases were diagnosed as early-onset moderate OHSS, including one case being hospitalized in group C. No case of OHSS was found in group A. No incidence of late-onset OHSS or severe OHSS occured in the study. Discussion The hcg-imitated LH surge induces the dispersion of granulose cells around the oocytes. Thus, the oocytes are easy to be retrieved. The number of retrieved oocytes is closely correlated with the dose of hcg. This study demonstrated statistical and clinical equivalence of three doses of urinary hcg in moderate or high responders for induction of final follicular maturation in patients undergoing IVF. The heavy of this study is its large scale. Our study has adequate power for achieving our primary and secondary outcome measures such as pregnancy rates and incidence of OHSS. hcg has been used in various IVF treatment protocols to induce final maturation but there is as yet no agreement on the minimum dose required. Studies in nonhuman primates have shown that hcg doses 3- to 10-fold lower than standard doses have been sufficient to re-initiate meiosis and induce luteinization of granulosa cells [14]. Abdalla et al. [7] reported that the oocyte recovery rate in patients who received IU hcg was lower compared with patients who received either IU or IU hcg, but the study was performed two decades ago and it was possible to make room for the development of ART. The later studies in an effort to reduce the risk of OHSS in high responder patients using IU [8], IU [6], with the promising pregnancy outcome. Up to our known, it is the first large scale study to establish a hcg dose of IU as an effective dose for triggering ovulation in IVF/ICSI cycles. On the other hand, the common dose of IU or IU hcg is proved that it could not only induce ovulation, but also mean a long lasting stimulation of the luteal body for the next days. In this study, whether the lower dose of hcg plays a reduced role in luteal support could not be explored due to cancel all fresh embryo transfer cycles. Lower dose of hcg may affect the maturity of ooplasm, the quality of embryo and the development of early embryo, so we generalized the research results with caution that patients may have different thresholds for follicular response to hcg and the recommended minimum dose of hcg should be at least IU. 156

7 Another highlight of the study is the low incidence of OHSS. Moderate to severe OHSS has been calculated to occur in 0.2% to 2% of all ovarian stimulation cycle [15]. Triggering with IU or IU appears to be effective as far as oocyte recovery is concerned. However, both dosing schedules may lead to severe OHSS [16]. With its relatively long serum half-life, hcg has certain detrimental side effects. The persistence of hcg in the serum after administration can lead to delayed ovulation from smaller follicles, development of multiple corpora lutea, sustained luteotropic effects and an increased risk of OHSS. Therefore, reducing the dose of hcg regimen can be useful in decreasing the risk of OHSS in moderate or high ovarian responders. Cryopreserving of all embryos with transfer in a subsequent cycle protects a patient from late onset OHSS. FET also avoids the negative effects of embryo-endometrium asynchrony in fresh stimulation cycles and improves the pregnancy outcome [13,17]. Thus, it provides many clinical benefits, including increasing the cumulative pregnancy rate and reducing the risk of OHSS. In conclusion, the study demonstrated that an hcg dose of IU for moderate or high responders led to similar efficacy compared with a dose of IU in inducing oocyte maturation without adversely affecting the pregnancy outcome. At the same time, the risk of OHSS in a high responder population is dramatic eliminated, therefore, the strategy of reducing trigger dose of hcg and cryopreserving all embryos for later transfer is recommended for the patients with high-risk OHSS in IVF treatment. References 1. Strickland TW, Puett D. Contribution of subunits to the function of luteinizing hormone / human chorionic gonadotropin recombinants. Endocrinology, 1981, 109(6): Yen SSC, Lienera G, Little B, et al. Disappearance rate of endogenous luteinizing hormone and chorionic gonadotropin in man. J Clin Endocrinol Metab, 1968, 28(12): Navot D, Relou A, Birkenfeld A, et al. Risk factors and prognostic variables in the ovarian hyperstimulation syndrome. Am J Obstet Gynecol, 1988, 159(1): Delvigne A, Rozenberg S. Epidemiology and prevention of ovarian hyperstimulation syndrome (OHSS): a review. Hum Reprod Update, 2002, 8(6): Lin HY, Wang WJ, Li Y, et al. Triggering final oocyte maturation with reducing doses of hcg in IVF/ICSI: a prospective, randomized and controlled study. Eur J Obstet Gynecol Reprod Biol, 2011, 159(1): Schmidt DW, Maier DB, Nulsen JC, et al. Reducing the dose of human chorionic gonadotropin in high responders does not affect the outcomes of in vitro fertilization. Fertil Steril, 2004, 82(4): Abdalla HI, Ah-Moye M, Brinsden P, et al. The effect of the dose of human chorionic gonadotropin and the type of gonadotropin stimulation on oocyte recovery rates in an in vitro fertilization program. Fertil Steril, 1987, 48(6): Nargund G, Hutchison L, Scaramuzzi R, et al. Low-dose HCG is useful in preventing OHSS in high-risk women without adversely affecting the outcome of IVF cycles. Reprod Biomed Online, 2007, 14(6):

8 9. Cummins JM, Breen TM, Harrison KL, et al. A formula for scoring human embryo growth rates in in vitro fertilization: its value in predicting pregnancy and in comparison with visual estimates of embryo quality. J In Vitro Fertil Embryo Transf, 1986, 3(5): Nardo LG, Ron-EI R, Rizk B. Symposium-- Update on prediction and management of OHSS: introduction to guest symposium. Reprod Biomed Online, 2009, 19(1): Liu XY, Xue SG, Jin W, et al. Impact of incubation time of vitrification-warming embryos on frozen-thawed embryo transfer outcomes. J Reprod Med, 2010, 19(2): Balaban B, Urrman B, Ata B, et al. A randomized controlled study of human Day 3 embryo cryopreservation by slow freezing or vitrification: vitrification is associated with higher survival, metabolism and blastocyst formation. Hum Reprod, 2008, 23(9): Aflatoonian A, Oskouian H, Ahmadi S, et al. Can fresh embryo transfers be replaced by cryopreserved-thawed embryo transfers in assisted reproductive cycles? A randomized controlled trial. J Assist Reprod Genet, 2010, 27(7): Zelinski-Wooten MB, Hutchison JS, Trinchard-Lugan I, et al. Initiation of periovulatory events in gonadotrophin-stimulated macaques with varying doses of recombinant human chorionic gonadotrophin. Hum Reprod, 1997, 12(9): Binder H, Dittrich R, Einhaus F, et al. Update on ovarian hyperstimulation syndrome: Part 1-incidence and pathogenesis. Int J Fertil Womens Med, 2007, 52(1): Kolibianakis EM, Papanikolaou EG, Tournaye H, et al. Triggering final oocyte maturation using different doses of human chorionic gonadotropin: a randomized pilot study in patients with polycystic ovary syndrome treated with gonadotropin-releasing hormone antagonists and recombinant follicle-stimulating hormong. Fertil Steril, 2007, 88(5): Delvigne A, Rozenberg S. Systematic review of data concerning etiopathology of ovarian hyperstimulation syndrome. Int J Fertil Womens Med, 2002, 47(5): (Received on April 25, 2013) 158