Elective single embryo transfer: the value of cryopreservation

In-vitro fertilization is associated with a high rate of multiple pregnancies, a consequence of the number of embryos transferred. There is a challenge in avoiding even twin pregnancies in assisted reproduction, and this can be accomplished with elective single embryo transfer and a good cryopreservation programme. In our follow-up study, we analysed all our elective single embryo transfers during 1998-1999. In all these cycles at least one embryo was frozen. A total of 127 elective single embryo transfers were performed with a clinical pregnancy rate of 38.6%. The highest implantation rate was obtained with four-cell embryos with <10% fragmentation (39.8%). Thirty-four patients have delivered (26.8%), one of these being a monozygotic pregnancy. In total 129 frozen-thawed cycles have been achieved in 83 patients. One frozen-thawed embryo has been transferred in 46 cycles with a clinical pregnancy rate of 17.4%, and two embryos have been transferred in 83 cycles, with a clinical pregnancy rate of 37.3%. Up until now, 66 of 125 patients in our single embryo transfer programme have delivered or have on-going pregnancies, and 77 still have embryos frozen. The cumulative delivery rate per oocyte retrieval is 52.8% and the twin rate 7.6%. We conclude that elective single embryo transfer with a good cryopreservation programme results in very acceptable pregnancy rates with a low risk of twins. This is a cost-effective practice that substantially reduces all risks associated with multiple pregnancies and lowers the cost per delivery.     

Experience with the elective transfer of two embryos under the conditions of the german embryo protection law: results of a retrospective data analysis of 2573 transfer cycles

The German embryo protection law (Embryonenschutzgesetz, ESchG) does not allow embryo selection. Therefore, only as many oocytes at the pronuclear stage (PN), as are planned to be transferred, are allowed to be cultured. It is not known whether, under these conditions, it is possible to reduce the number of embryos for transfer without a corresponding reduction of the overall pregnancy rate (PR). We retrospectively analysed 2573 consecutive transfer cycles following either in-vitro fertilization (IVF) or IVF/intracytoplasmic sperm injection. Out of these cycles, 234, 329 and 792 were performed with one, two, and three embryos respectively, because only that number was available (non-elective transfer). Another 123 and 1095 transfer cycles were performed with two and three embryos, respectively, which were selected from a higher number of PN oocytes (elective transfer). The clinical ongoing PR were 3.9, 9.1 and 17.7% respectively for the groups with non-elective transfer of 1, 2 and 3 embryos, and 22.0 and 22.5% for the groups with elective transfers with two and three embryos, respectively. There was no statistically significant difference in PR between the two elective embryo transfer groups up to the age of 40 years. The multiple pregnancy rate was reduced by 7.9%. The reduction of the number of embryos transferred from three to two can be performed even under the conditions of the ESchG without an effect on the overall PR.     

Comparison of two elective transfer policies of two embryos to reduce multiple pregnancies without impairing pregnancy rates.

A first elective transfer policy of two embryos based solely on embryo morphology was compared to a more restrictive policy transferring two embryos to all patients aged < 35 years with less than three previous cycles to reduce the incidence of multiple pregnancies. With a significant reduction in the number of triple transfers from 72.4 to 44.3%, the delivery rates were similar for both policies, 31 and 32.1%. However, the multiple pregnancy rates per transfer significantly decreased from 12.5 to 7.8% (P < 0.05). Of 99 pregnancies, only 24.2% were multiple including 1% of triplets compared to 40.7% multiple pregnancies including 6.7% of triplets for the first policy. Forty-eight transfers of two average embryos with the new policy were compared to 264 transfers of three average embryos with the old policy. Multiple pregnancy rates per transfer were significantly reduced by a third from 23 to 8% (P < 0.05) without a reduction of the pregnancy rates (42 and 48%). This study demonstrated that elective transfer of two embryos reduced the number of multiple pregnancies without impairing the pregnancy rates even with the transfer of average embryos.     

血LH峰与尿LH峰测定判断冻融胚胎移植时机的方法学比较

目的研究利用电化学发光免疫分析技术监测血LH板或利用尿LH板监测尿LH峰判断冻融胚胎移植时机的方法学比较。方法本中心由1999年5月至今共完成冻融胚胎移植67例,排除冻融胚胎移植周期中所移植的胚胎全部为部分卵裂球受损胚胎的周期后,将其中61例移植周期随机分成A、B两组,A组共12周期,通过使用尿LH板测定尿LH峰来判断冻融胚胎移植时机,B组共49个周期,通过电化学发光免疫分析技术测定血LH峰来判断冻融胚胎移植时机,对两组资料进行回顾性分析。结果两组患者平均冻融胚胎移植数目、冷冻前胚胎形态学评分及解冻后胚胎卵裂球存活程度等均无显著差异(P>0.05),冻融胚胎移植周期的子宫内膜厚度均大于8mm。利用尿LH峰测定判断冻融胚胎移植时机的12周期中,移植冻融胚胎37个,平均每周期移植胚胎3.1±0.4个,周期临床妊娠率33.3%(4/12)。利用血LH峰测定判断冻融胚胎移植时机行冻融胚胎移植的46例49个周期中,移植冻融胚胎137个,平均每周期移植胚胎2.8±0.1个,周期临床妊娠率63.3%(31/49),两组资料临床妊娠率有非常显著性差异(P<0.01)。结论利用电化学发光免疫分析技术监测血LH峰判断冻融胚胎移植时机比利用尿LH板监测尿LH峰判断冻融胚胎移植时机更为准确和灵敏,显著提高临床妊娠率。     

Comparison of two recombinant follicle-stimulating hormone preparations in in-vitro fertilization: a randomized clinical study.

A randomized comparison of two recombinant human follicle-stimulating hormone (recFSH) preparations (Gonal-F and Puregon) in ovarian stimulation for in-vitro fertilization (IVF) or intracytoplasmic sperm injection (ICSI) was carried out at the Infertility Clinic of the Family Federation of Finland. A total of 348 women (aged 22-43 years) suffering from infertility due to miscellaneous causes was recruited. Of these, 344 underwent stimulation using equal starting doses (150 IU/day: Gonal-F n = 164, Puregon n = 158 or 300 IU/day: Gonal-F n = 8, Puregon n = 14) after down-regulation with intranasal buserelin from the mid-luteal phase. Similar clinical pregnancy rates were achieved with both preparations; 33.5% per cycle and 37.4% per embryo transfer (24.5% one-embryo and 75.5% two-embryo transfers, n = 147) with Gonal-F (150 IU/day) and 32.9% per cycle and 36.4% per embryo transfer (30.1% one-embryo and 69.9% two-embryo transfers, n = 145) with Puregon (150 IU/day). The ongoing cumulative pregnancy rates after frozen-thawed embryo transfer were 35.4% with Gonal-F and 37.7% with Puregon. Six cycles were cancelled because of a low response (three in each group). Similar numbers of oocytes were obtained in both groups; 13.0 with 150 IU/day and 6.1 with 300 IU/day Gonal-F, and 12.4 with 150 IU/day and 7.1 with 300 IU/day Puregon. The fertilization and cleavage rates and the incidence of moderate or severe ovarian hyperstimulation syndrome (Gonal-F, 2.0% and Puregon, 0.7%) were also similar. Gonal-F and Puregon were equally and highly effective in stimulation for IVF and ICSI.     

One year's experience with elective transfer of two good quality embryos in the human in-vitro fertilization and intracytoplasmic sperm injection programmes

High incidences of multiple pregnancies, after transferringa maximum of three embryos, were observed after in-vitro fertilization(IVF) treatment. In a randomized study, it was demonstratedthat, after taking into account embryo quality and other positivelyinterfering parameters, an elective transfer of two good qualityembryos does not significantly influence the pregnancy rate.The intracytoplasmic sperm injection (ICSI) technique was successfullydeveloped in the meantime and high incidences of multiple pregnancieswere also obtained after ICSI. The question arose whether afterICSI there was also room for elective double embryo transferin a well-defined patient group. This report covers 1 year of IVF and ICSI treatment and theresults are presented in relation to the number of embryos transferred.The embryo development is similar for zygotes obtained afterIVF and ICSI; for both techniques 63% of the zygotes developto type A-B embryos and 13% to type C embryos. There is alsono difference in the pregnancy rate after ICSI or IVF. Globally,after IVF, 307 out of the 766 double and triple transfers (40.1%)and 317 out of 774 double and triple transfers (40.9%) afterICSI resulted in a positive HCG. After IVF, 73.9% (227) andafter ICSI 76.3% (242) of the pregnancies were evolutive. Neitherwas there any difference between the two techniques as regardsthe implantation rate per transferred embryo. After IVF, 22.8%of the transferred embryos implanted compared with 21.8% afterICSI. When the elective double embryo transfers were compared,no difference was found between IVF and ICSI. After IVF, 102of the 211 elective double transfers (48.1%) resulted in a pregnancyversus 93 out of 225 (41.3%) after ICSI [not significant (NS)].A high implantation rate per transferred embryo (IVF: 33.2%;ICSI: 26.9%, NS) was obtained in this elective double transfercategory, as was also reported in the randomized study. Thesedata confirm the results obtained in our randomized study andthe effectiveness of the elective double embryo transfer forIVF as well as for ICSI.     

Characterization of a top quality embryo, a step towards single-embryo transfer.

In most in-vitro fertilization (IVF)/intracytoplasmic sperm injection (ICSI) programmes approximately one ongoing pregnancy in three is multiple. The need to characterize embryos with optimal implantation potential is obvious. We retrospectively examined all of 23 double transfers resulting in ongoing twins, occurring between January 1, 1996 and May 19, 1997. Characteristics of these top quality embryos were absence of multinucleated blastomeres, four or five blastomeres on day 2, seven or more cells on day 3, and 2 embryos, 11/31 (35%) were multiple. We applied our top quality criteria to the 221 double transfers: 106 transfers with two top embryos resulted in 65 (63%) ongoing pregnancies with 37 (57%) twins, 65 transfers with one top embryo in 38 (58%) ongoing pregnancies with eight (21%) twins. In the group without top embryos, 12/52 (23%) ongoing singletons occurred, with no twins. The corresponding ongoing implantation rates were 49, 35 and 12%. This analysis suggests that single embryo transfer with an acceptable pregnancy rate might be considered if a top quality embryo is available.     

Elective single embryo transfer yields good delivery rates in oocyte donation

BACKGROUND: High pregnancy rates have been noted after oocyte donation (OD). Multiple pregnancies should be avoided, because oocyte recipients have an increased risk of obstetric complications. METHODS: We analysed our OD results from 2000-2001 when elective single embryo transfer (eSET) was introduced as a recommended policy for all recipients if at least one good quality embryo was available. The results were compared with those achieved in 1998-1999, when usually two embryos were transferred (double embryo transfer, DET). Between 1998 and 2001, 100 healthy women donated oocytes and 135 fresh embryo transfers were carried out. The mean age of the donors was 31 years and that of the recipient women was 35 years. RESULTS: The proportion of eSET of all OD transfers was 17.1% in 1998-1999 and 61.0% in 2000-2001. There was no statistically significant difference in clinical pregnancy (36.8 versus 45.8%) and delivery rates (31.6 versus 33.9%) per embryo transfer between the two time periods. The proportion of twins declined from 29% (1998-1999) to 10% (2000-2001). The delivery rate was similar after eSET and DET (32.6 versus 32.1% respectively). CONCLUSIONS: By increasing the proportion of eSETs it is possible to reduce the number of twins without affecting delivery rates in oocyte recipients.     

Maternal serum hCG and alpha-fetoprotein levels in pregnancies conceived after IVF or ICSI with fresh and frozen-thawed embryos

BACKGROUND: Studies have shown that levels of serum markers of Down's syndrome were altered in pregnancies conceived after IVF, though the reason for this remains unknown. METHODS: Second-trimester maternal serum levels of hCG and alpha-fetoprotein (AFP) in pregnancies conceived with fresh and frozen-thawed embryos after assisted reproduction were compared with those conceived spontaneously. RESULTS: There were 203 pregnancies with fresh embryo transfers (130 IVF cases, 73 ICSI cases) and 98 pregnancies with frozen-thawed embryo transfers (61 IVF cases, 37 ICSI cases). The controls consisted of 17 145 spontaneous pregnancies. The median hCG multiples of the median (MoM) was significantly increased to 1.24 in 98 pregnancies conceived after frozen embryo transfer. This elevation was observed only in the IVF-frozen embryo transfer subgroup (P < 0.001), but not in the ICSI-frozen embryo transfer subgroup. The median AFP MoM for 203 pregnancies after fresh embryo transfer was 0.90. Among the subgroups, the median AFP MoM was significantly reduced to 0.90 and 0.86 in IVF-embryo transfer (P = 0.04) and ICSI-embryo transfer (P = 0.001) pregnancies respectively, and significantly raised to 1.20 in the IVF-frozen embryo transfer subgroup. CONCLUSIONS: The degree of alterations in maternal serum hCG and AFP levels varied between fresh and frozen-thawed embryos, and also between the mode of fertilization. Pregnancies resulting from ICSI or frozen embryo transfer should be regarded as distinct entities from those of IVF-embryo transfer.     

Transfers of frozen-thawed human embryos in cycles stimulated by HMG

A total of 130 transfers of frozen-thawed (F-T) human embryos was carried out after moderate ovarian stimulation with human menopausal gonadotrophin (HMG). Embryos were replaced 3 days after the spontaneous luteinizing hormone (LH) surge or 4 days if ovulation was induced by human chorionic gonadotrophin (HCG). Embryos were thawed a few hours prior to transfer. One-hundred-and-twenty-three transfers were effective and 23 pregnancies were achieved. The rate of ongoing pregnancies per transfer was 17.9% (22/123). The survival rate of embryos originating from cycles stimulated by a combination of an LHRH analogue and HMG in a long protocol (LA-HMG protocol) was significantly lower when compared with the rate of embryos retrieved from clomiphene citrate-HMG (CC-HMG protocol) stimulated cycles (52 versus 67%, P less than 0.05). When fresh embryos originated from cycles stimulated with an LHRH analogue and HMG in a short protocol (SA-HMG protocol), the survival rate was not affected (59 versus 67%, NS). Although the difference was not significant, the ongoing pregnancy rate per transfer according to the three protocols from which the embryos originated seemed to be better with the SA-HMG protocol: 16% with the CC-HMG protocol, 14.5% with the LA-HMG protocol versus 27.6% with the SA-HMG protocol. The success rate was independent of the number of F-T transferred embryos if at least one embryo with 100% intact blastomeres was replaced.     

Endocrinology: Long-term evaluation of implantation of fresh and cryopreserved human embryos following ovarian stimulation with buserelin acetate-human menopausal gonadotrophin (HMG) or clomiphene citrate-HMG

This study is a long-term evaluation of the total pregnancypotential of cohorts of fresh and cryopreserved sibling embryosfrom in-vitro fertilization (TVF) cycles stimulated with eitherthe gonadotrophin-releasing hormone analogue buserelin (BUS)(long protocol) or clomiphene citrate (CC) both in combinationwith human menopausal gonadotrophin (HMG). Therefore a retrospectiveanalysis was performed on patients who entered the FVT programmebetween January 1986 and July 1987 and who had triple embryotransfer in the collection cycle. Significantly more fertilizedoocytes developed to good-quality embryos in the CC-HMG group(86.1%) than in the BUS-HMG group (80.8%). Transfer of the threemorphologically best-looking embryos was performed on day 2post-insemination in 106 CC-HMG and 80 BUS-HMG cycles. Supernumeraryembryos were cultured for a further 24 h and multicellular embryoswith up to 20% of fragments were frozen slowly with 1.5 M dimethylsulphoxideon day 3 post-insemination (162 embryos in CC-HMG cycles, 102embryos in BUS-HMG cycles). Outcome was measured by embryo survivalrate, embryo implantation rate and delivery rate in fresh andfrozen embryo transfers. Delivery rates were 31.3 and 21.7%per fresh embryo transfer in BUS-HMG and CC-HMG cycles respectively.Fresh embryo implantation rates were significantly higher incollection cycles stimulated with BUS-HMG (17.9%) than in cyclesstimulated with CC-HMG (113%). Implantation rates were significantlyenhanced in embryos transferred in excess of one in cycles leadingto pregnancy, perhaps indicative of higher embryo quality inBUS-HMG cycles. Almost all cryopreserved embryos have by nowbeen thawed, so the contribution of frozen embryos to overallpregnancy rates can be evaluated. Overall morphological survivalrates of frozen-thawed embryos were similar for 140 embryosfrom CC-HMG cycles (50%) and 100 embryos from BUS-HMG cycles(46%). The percentage of fully intact embryos was, however,significantly lower in the BUS-HMG group (19%) than in the CC-HMGgroup (39.5%). Delivery rates were significantly lower following30 transfers of frozen-thawed embryos from BUS-HMG-stimulatedcycles (3.3%) than following 42 transfers of frozen-thawed embryosfrom CC-HMG cycles (19.1%). Embryo implantation rates were lowerfor frozen-thawed embryos from BUS-HMG cycles (23%) than fromCC-HMG cycles (12.7%). Here we demonstrate that ovarian stimulationwith the long protocol BUS-HMG instead of the CC-HMG protocolled to higher embryo implantation rates in collection cyclesbut to lower intact embryo survival rates and to lower embryoimplantation rates for frozen sibling embryos. Despite the lowerimplantation rates with frozen embryos originating from theBUS-HMG protocol, there was no significant difference betweentotal delivery rate per transfer from cycles stimulated withCC-HMG (30.2%) compared with BUS-HMG (33.8%).     

Prognostic factors for the success rate of embryo freezing

To find some prognostic factors for the outcome of frozen-thawed cycles, we have retrospectively analysed all frozen pre-embryos that were thawed during 1993 and 1994 at two in-vitro fertilization (IVF) units in Sweden. Supernumerary pre-embryos were frozen from 551 oocyte retrievals and these resulted in 660 frozen-thawed cycles which lead to 623 thawed embryo transfers. The outcome of these transfers was 137 clinical pregnancies with a pregnancy rate of 22% per frozen-thawed embryo transfers. Women <40 years of age had a higher birth rate than those > or =40 years, 19 and 5% respectively (P < 0.01). Transfers with two and three pre-embryos resulted in pregnancy rates of 23 and 27%, respectively, compared with 14% for transfer of one embryo. A pregnancy resulting from the initial embryo transfers had a predictive value for results of the subsequent frozen-thawed cycle. Embryo grade and cleavage stage at the time of freezing was important for the survival of the frozen-thawed pre-embryos. The pregnancy rate was not influenced by the cleavage stage, but a tendency toward a lower pregnancy rate was seen for the embryos with lower grading. To conclude, cryopreservation seems to be beneficial in women <40 years of age, who have supernumerary pre-embryos of good quality for freezing and of which at least two can be transferred.      

Is there any benefit from the culture of a single oocyte to a blastocyst-stage embryo in unstimulated cycles?

BACKGROUND: The aim of the study was to test the influence of 2- and 5-day cultivation of a single oocyte on the pregnancy rate in a non-stimulated cycle. METHODS: A retrospective chart review of 391 consecutive patients undergoing IVF and intracytoplasmic sperm injection in unstimulated cycles was performed. The embryos were kept in MediCult universal IVF medium for day 2 transfers and in BlastAssist System for day 5 transfers. RESULTS: The oocyte recovery rate in the group for 2-day cultivation and in the group for 5-day cultivation was similar, being 79.4 (162/204) and 83.6% (154/187) respectively. The same is true of the fertilization rate (73.8 versus 77.7%). The blastulation rate was 52.8%. The embryo transfer rate per cycle was higher when day 2 embryos were transferred: 64.8% (105/162) compared with 35.7% (55/154) if blastocyst-stage embryos were transferred. The pregnancy rate per transferred embryo was higher when a blastocyst was transferred (40.0%) instead of a day 2 embryo (23.8%). CONCLUSION: The expected pregnancy rate calculated per embryo available on day 2 of cultivation was similar in both groups (23.8 versus 22.2%) and it was not affected by oocyte culture to the blastocyst stage.     

Impact of patients' choice for single embryo transfer of a top quality embryo versus double embryo transfer in the first IVF/ICSI cycle

BACKGROUND: The aim of this study was to evaluate the impact of transferring a single top quality embryo in the first IVF/ICSI cycle of patients <38 years old who chose to have one or two embryos transferred. METHODS: A total of 262 patients participated in the study, and 243 transfers were performed: 156 (64%) patients chose the transfer of a single top quality embryo, if available, and two non-top quality embryos if not available; 87 (36%) patients chose to have a double embryo transfer regardless of embryo quality. RESULTS: In the first group an ongoing pregnancy rate of 40% (63/156) with a twin pregnancy rate of 2% (1/63) was achieved. In the second group the ongoing pregnancy rate was 44% (38/87) with 26% (10/38) twin pregnancies. In the patient group with only one embryo transferred, irrespective of the patient's choice, the ongoing pregnancy rate was 43% (54/127) with no twin pregnancies. For the study population as a whole, the ongoing pregnancy rate was 42% (101/243) with 11% (11/101) twins. CONCLUSION: We conclude that the introduction of single embryo transfer in the first IVF/ICSI cycle is highly acceptable in women <38 years old.     

Elective single day 3 embryo transfer halves the twinning rate without decrease in the ongoing pregnancy rate of an IVF/ICSI programme

BACKGROUND: Data on the effect of elective single embryo transfer (eSET) on the total and multiple pregnancy rates of an IVF/ICSI programme are reported. METHODS AND RESULTS: A retrospective cohort analysis of eSET was carried out over a 4 year period. A total of 1559 cycles resulted in 1464 transfers; 299 transfers of one top quality embryo (20.4%) and 86 of one non-top quality embryo (5.9%) yielded 149 conceptions (49.8%) with 105 ongoing pregnancies (35.1%) and 26 conceptions (30.2%) with 19 ongoing implantations (22.1%) respectively; 1079 transfers of two (n = 853; 58.3%) or more than two (n = 226; 15.4%) embryos yielded 366 ongoing pregnancies (33.9%). The ongoing pregnancy rates for the years between 1998 and 2001 were 35.9, 27.9, 31.9 and 31.0% per oocyte retrieval and 38.5, 29.4, 34.1 and 33.2% per transfer. There were no differences in pregnancy rates between any of the years. The average ongoing pregnancy rate (>12 weeks) over the 4 years was 31.5% per started cycle and 33.5% per transfer; the average number of embryos transferred decreased from 2.26 (1998) to 1.79 (2001); the multiple pregnancy and twinning rates dropped from 33.6 and 29.5% (1998) to 18.6 and 16.3% (2001) respectively. CONCLUSIONS: Judicious application of eSET can halve the twinning rate while maintaining the overall pregnancy rate.     

Delaying transfer to the third day post-insemination, to select non-arrested embryos, increases development to the fetal heart stage

The purpose of this study was to determine whether delayingembryo transfer by 24 h, until day 3 post-insemination, allowedimproved selection of non-arrested embryos for transfer. Wehave retrospectively analysed pregnancy rates in a large seriesof patients who had embryo transfer either on day 2 or on day3 post-insemination over a 27 month period. From January 1990to March 1992, 567 patients received embryo transfer on day2, and 661 patients had transfer on day 3 post-insemination,but these transfers were not contemporary. Pregnancy rates wereslightly higher in patients who had embryo transfer on day 3(37%) than in those patients who had their embryos transferredon day 2 (35%), but this difference was not significant. Theimplantation rate, as measured by the proportion of embryosdeveloping to the fetal heart stage, was significantly higherfollowing transfer on day 3 (23%) than after transfer on day2 (19%) (P < 0.05), suggesting that selection of viable embryosis improved on day 3. Furthermore, of the embryos which gaverise to a fetal sac, significantly fewer miscarried before thefetal heart stage (P < 0.05) following transfer on day 3(6%) than after transfer on day 2 (12%). Delaying transfer untilday 3 provides a further 24 h to observe embryo development.During this period 16% of embryos arrested or became developmentallyretarded; thus waiting until day 3 allowed these embryos tobe identified and avoided for consideration for transfer. Embryotransfer may be safely delayed until day 3, and this may helpin selecting embryos most likely to implant and develop aftertransfer.     

Day 2 elective single embryo transfer in clinical practice: better outcome in ICSI cycles

BACKGROUND: Single embryo transfer (SET) after IVF/ICSI has been shown to result in an acceptable pregnancy rate in selected subjects. In our unit, SET is routinely carried out among women under the age of 36 in the first or second treatment cycle when a top-quality embryo is available. In order to define further the selection criteria for SET, we have analysed the outcome of elective SET (eSET), including the cumulative pregnancy rate after frozen embryo transfers, performed in the years 2000-2002 in the Oulu Fertility Center. METHODS: During the study period, a total of 1271 transfers were performed, and in 468 cycles SET (39% of all transfers) was carried out. Of the SET cycles, in 308 cases a top-quality embryo was transferred on day 2 and extra embryos were frozen. Of these eSET cycles, ICSI was carried out in 87 cycles (28%). RESULTS: The overall clinical pregnancy rate per transfer was 34.7% in the eSET cycles. In the eSET ICSI cycles, the clinical pregnancy rate was significantly higher than in the corresponding IVF cycles (50.6 versus 28.5%, P < 0.001). The cumulative pregnancy rate per patient after fresh and frozen embryo transfers was also significantly higher after ICSI (71.2 versus 53.4%, P < 0.01). CONCLUSIONS: A high cumulative pregnancy rate per oocyte retrieval can be achieved after eSET in daily clinical practice. The implantation rate of fresh top-quality embryos in the ICSI cycles was significantly higher than in the IVF cycles, possibly due to more successful selection of the embryo for embryo transfer on day 2 after ICSI. In addition, our data suggest that embryo quality is a more important determinant of outcome than the age of the woman.     

Fertilization and early embryology: The prognostic value of successful in-vitro fertilization in subsequent trials

A retrospective study comparing in-vitro fertilization (IVF)results in patients with previous successful trials versus newIVF patients was designed with the objective of evaluating theprognosis in both groups. Patients were divided into two groups:group A, 22 patients with previous conception in IVF trials;and group B, 235 new IVF patients. All patients had tubal factoras the only cause of infertility and were stimulated by a standardprotocol of gonadotrophin-releasing hormone agonist and humanmenopausal gonadotrophin. The pregnancy rate in group A (64%)was significantly higher than in group B (19%). In group A,77% of the patients had three or more grade 1 embryos per transferas compared with 16% in group B. In group A, 95.5% of patientshad easy embryo transfer as compared with 61.2% in group B.The results of the study demonstrated that patients with previousIVF pregnancies have a significantly higher pregnancy rate comparedwith the control group. The improved pregnancy rate is due tothe higher quality of embryos and the higher percentage of easyembryo transfers.     

A prospective randomized study: day 2 versus day 5 embryo transfer

BACKGROUND: This randomized controlled study was performed in an unselected IVF/ICSI population to test the hypothesis that blastocyst transfers result in higher clinical pregnancy rates (CPR) per oocyte retrieval when compared with day 2 transfers. METHODS: Blind randomization for transfer on day 2 (group 1) or day 5/6 (group 2) was performed before stimulation. Oocytes and embryos were cultured in sequential media in 5.5% CO(2), 5% O(2), 89.5% N(2) and 90% humidity. A maximum of two embryos was transferred. RESULTS: The two groups were similar for age, IVF indication, number of treatment cycles, rate of ICSI/IVF, number of fertilized oocytes and number of embryos transferred. The CPR/oocyte retrieval was comparable in group 1 (32%) and in group 2 (44%), while the CPR/embryo transfer was significantly higher (P < 0.01) in group 2 (60%) than in group 1 (35%). Similarly, the implantation rate per embryo transferred was significantly higher (P < 0.03) in group 2 (46%) than in group 1 (29%). The cryo-augmented delivery rate/oocyte retrieval was comparable in group 2 (36.3%) and in group 1 (28.6%). CONCLUSION: This randomized study in an unselected population showed a significantly higher CPR/embryo transfer and a tendency toward a higher CPR/oocyte retrieval in patients receiving blastocysts when compared with day 2 transfers.     

Pregnancies achieved after frozen-thawed pronuclear oocytes obtained by intracytoplasmic sperm injection with spermatozoa extracted from frozen-thawed testicular tissues from non-obstructive azoospermic men.

The use of frozen-thawed testicular tissue as a source of spermatozoa for intracytoplasmic sperm injection (ICSI) in non-obstructive azoospermia yields favourable fertilization and pregnancy rates while avoiding both repetitive biopsies and unexpected cycle cancellations. Spermatozoa were obtained from frozen-thawed testicular biopsy specimens from 67 non-obstructive azoospermic men. Following fertilization, supernumerary two pronuclear (2PN) oocytes were frozen. After thawing, 17 cycles of embryo transfer were carried out with a mean number of 2.7 embryos and a mean cumulative embryo score (CES) of 18.3 per transfer. The clinical pregnancy and implantation rates per transfer in these cycles (23.5 and 8.3% respectively) were comparable to those of fresh embryo transfers (35.7 and 12.7% respectively) with a mean number of 2.7 embryos and a mean CES of 28.7 per transfer. Abortion rates, although higher with cryopreserved 2PN oocytes were not significantly different. With this approach, cryopreservation of supernumerary 2PN oocytes can be used to improve the cumulative pregnancy rates in a severely defective spermatogenetic population. To our knowledge, these are the first pregnancies reported which have been obtained by the transfer of cryopreserved pronuclear oocytes obtained from ICSI using cryopreserved testicular spermatozoa.