The contribution of embryo cryopreservation to in-vitro fertilization/gamete intra-Fallopian transfer: 8 years experience

In this paper, the authors summarized their experience withembryo cryopreservation over an 8-year period. The results,therefore, reflect the long-term benefit of embryo cryo-preservationto the overall in-vitro fertilization/gamete intra-Fallopiantransfer (IVF/GIFT) programme and to the women who had embryoscryopreserved. The stable survival rate of thawed embryos andpregnancy rate, especially over the past 4 years, suggests thatthe results can reliably be used to evaluate the efficacy ofthe embryo cryopreservation programme. The ongoing pregnancyrate of frozen/thawed embryo transfer is 10.9%, comparable withthe ongoing pregnancy rate of fresh IVF/embryo transfer in ourunit over the same period. In addition to those factors knownto affect the pregnancy rate in fresh IVF/GIFT cycles, suchas age of the recipients and number of embryos transferred,the major factor affecting the efficacy of the cryopreservationprogramme is the number of oocytes retrieved in the initialstimulation cycle, and the number of embryos available for cryopreservation.The storage time of cryopreserved embryos will also have a significanteffect on the realization of the total potential of embryo cryopreservation.Overall the contribution of cryopreservation to our IVF/GIFTprogramme is substantial, increasing pregnancy rate by 4%, whilethe greater net benefit, of course, is for the women who hadembryos cryopreserved (pregnancy rate increased by 7%), especiallyfor those who returned for frozen/thawed embryo transfer cycles(pregnancy rate increased by 11%).     

Fertilization and early embryology: Granulosa cells improve human embryo development in vitro

A total of 17 couples with repetitive implantation failure aftertransfer of fresh or frozen—thawed embryos had half oftheir zygotes cultured in standard conditions and frozen atday 2 after insemination, and the other half cocultured withautologous granulosa cells and transferred at the morula orblastocyst stage at day 5 or 6 after oocyte retrieval. At theend of the culture period, supernatants of cocultures were recoveredfor steroid assays. Monolayers were stained for granulosa cellgrowth and morphological assessment. We observed that granulosacells improve embryo development in vitro since 32 out of 60(53%) reached the morula stage and 18 (30%) the blastocyst stage,leading to a total of 83% embryos available for transfer (comparedwith 3% without coculture). The ongoing pregnancy rate of thesepatients who were selected because they had at least three previousimplantation failures, is only 5.9%, however, which is similarto the control group without coculture (6.3%). To conclude,granulosa cells improve embryo development but not the pregnancyrate after transfer of cocultured embryos in patients with multipleprevious implantation failures.     

The value of IVF-ET in patients undergoing treatment by the GIFT procedure

In patients undergoing the gamete intra-Fallopian transfer (GIFT)procedure, a prospective study was perfonned to establish thepredictive value of attempting in-vitro fertilization (IVF)using extra oocytes obtained at laparoscopy and also the valueof transferring the resulting embryo(s), in conjunction withGIFT, in the same treatment cyde. The GIFT procedure was performedin 50 treatment cycles involving 43 patients, of whom 20 haveachieved clinical pregnancy with an overall success rate of40% per treatment cycle. In 38 of these patients, one or moreextra oocytes were available and an attempt was made in eachcase to fertilize them in vitro. When fertilization failed tooccur in vitro, the chances of pregnancy were significantlyreduced (9.1%). In patients for whom IVF of extra oocyte(s)was successful, there was no significant difference In the pregnancyrate whether embryo transfer was performed or not (54 and 57.1%,respectively). The success rate was also influenced by the numberof oocytes collected rather than the number of oocytes/embryostransferred. Therefore these results suggest that IVF of extraoocytes is a good indicator of in-vlvo fertilization and thatIf extra embryos are obtained they should be cryopreserved.     

Synchronization of donor's and recipient's cycles with GnRH analogues in an oocyte donation programme

In this oocyte donation programme nine female donors were stimulated using a combination of GnRH analogues and human menopausal gonadotrophins. A total of 149 oocytes were retrieved. Thirty fresh embryos were transferred in 14 uterine replacements, resulting in four pregnancies and 15 fertilized oocytes were placed in the Fallopian tube of six recipients, yielding two pregnancies. A mean number of 2.2 embryos was replaced. The implantation rate per embryo was 13%. Furthermore 36 embryos were cryopreserved for later use. Following 20 replacements, six pregnancies were established (30% per transfer); since two patients aborted, the ongoing pregnancy rate was 20%.     

Comparative results on survival of human and animal eggs using different cryoprotectants and freeze-thawing regimens. II. Human

A total of 269 human pronuclear embryos and 84 oocytes weresubjected to four different protocols of cryoprotectant equilibration,washing out and freeze-thawing. The morphological survival,rate of development, fertilization in vitro and overall survivalrate were estimated in the groups of fresh, aged oocytes, diploidand multipronuclear embryos used. With some restrictions, theconclusion can be drawn that slow, low intermediary temperature1, 2-propanediol (1, 2-PROH) and 1, 2-PROH/dimethyl sulphoxide(DMSO) systems are superior to the rapid, high intermediarytemperature 1, 2-PROH and the traditionally used DMSO systems.The best success rates were reached with the combination ofcryoprotectants in the low intermediary temperature group. Thirty-threepatients had 37 transfers of cryopreserved pronuclear embryos(n= 103), resulting in eight pregnancies (24.2% per transfer)thus doubling the pregnancy rate in the stimulation cycles forthe same period (21% per transfer). Thawing at a rate of 50?C/minis not incompatible with the survival of slowly frozen humanoocytes and pronuclear embryos cooled to an intermediary temperatureof –70?C using the DMSO system.     

Outcome of intracytoplasmic sperm injection with testicular spermatozoa in obstructive and non-obstructive azoospermia

From 1 August 1993 until 30 September 1994, 69 couples sufferingfrom azoospermia underwent testicular sperm extraction and intracytoplasmicsperm injection. In 50 couples with obstructive azoospermiaa total of 631 meta-phase-II oocytes were injected after testicularsperm extraction yielding a 2-PN fertilization rate of 57%.In female patients <40 years of age an ongoing pregnancyrate per transfer of 42% (14/33) was obtained. So far, eighthealthy babies have been born, including two singletons andthree twin gestations. In 19 couples with non-obstructive azoospermiaa total of 264 metaphase-II oocytes were injected after testicularsperm extraction, yielding a 2-PN fertilization rate of 58%.An ongoing pregnancy rate per transfer of 31% (5/16) was established.So far, six healthy babies have been born including one singleton,one twin and one triplet gestation.     

Fertilization in vitro of human oocytes by spermatozoa collected in different stressful situations

It has been shown that semen quality is impaired in couplesundergoing in-vitro fertilization (IVF), probably due to stress.A possible effect of stress on the ability of spermatozoa tofertilize human oocytes in vitro was analysed in the presentstudy composed of 26 couples with normozoospermic men undergoingIVF. A semen sample was obtained during the infertility work-upand was cryopreserved (sample 1). A second sample (sample 2)was provided after oocyte retrieval during the IVF cycle. Sample1 was thawed and both samples were washed and preincubated foroocyte insemination. One-hundred-and-five oocytes were inseminatedusing thawed sample 1, and 120 with sample 2.Semen parameterssuch as density, progressive motility and percentage of abnormalforms were compared between sample 1, before and after freezing,and sample 2. Only motility was significantly (P<0.01) decreasedby cryopreservation in sample 1, but no parameter was significantlydifferent when fresh sample 1 was compared to sample 2. Thefertilization rate was 78.6% using sample 1 in comparison to87.5% when sample 2 was employed (not significant, NS). Cleavagerates were 77.7 and 89.7%, respectively (NS). A group of fivepatients undergoing IVF who needed donor semen served as a controlfor the effect of sperm cryopreservation on IVF. In these cases,the donor was asked to provide a fresh sample. Half of thissample was frozen and thawed. Subsequently, fresh and thawedsamples were prepared for insemination and oocytes inseminatedeither with the fresh preparation (n=24) or the frozen and thawedspermatozoa (n=22). There was a significant (P<0.05) decreasein motility in the thawed sample, but fertilization and cleavagerates were not different. These data suggest that the stressfulsituation induced by IVF treatment in normozoospermic men doesnot affect the ability of spermatozoa to fertilize human oocytesin vitro. Cryopreservation of human spermatozoa before IVF maybe a good policy in couples especially suspected of being understress during this procedure.     

Comparison of SUZI and ICSI for severe male factor

We compare the results of subzonal insemination (SUZI) and intracytoplasmicsperm injection (ICSI) carried out between February 1993 andend of August 1994. A total of 232 couples underwent 302 cyclesof micro-assisted fertilization (79 patients had SUZI for atotal of 93 cycles, 153 patients ICSI for a total of 209 cycles).The indications for treatment were obstructive azoospermia in35 cycles, ejaculatory failure with severely low sperm countin 7 cycles, and failure of fertilization in a previous IVFcycle or less than 10% of oocytes fertilized in 87 cycles. In173 cycles the indication for treatment was a poor semen parameter.Patients undergoing ICSI had significantly higher fertilizationrates [43 (728/1692) versus 22.3% (151/676), ² = 86.308, P <0.0001], better chances of embryo transfer [95 (199/209) versus73% (68/93), ² = 30.671, P < 0.001], and greater numbersof embryos transferred (2.4 ± 0.9 versus 1.6 ±1.2 F = 42, P < 0.0001) than patients who had SUZI. Eighteenpatients became pregnant following the SUZI procedure, a pregnancyrate of 19% per egg collection, compared with 28% for thosewho underwent the ICSI procedure, where 58 out of 209 becamepregnant. The pregnancy rate was similar in those who underwentembryo transfer, whether they had ICSI or SUZI (29.2 and 28.6%respectively). Overall, the pregnancy rate doubled with eachnumber of embryos transferred, so it was 8.9% when one embryowas transferred, which increased to 18.3% when two embryos weretransferred, and this rose to 37.7% when three embryos weretransferred. There was no significant difference in the pregnancywastage rate between SUZI and ICSI. None of the offspring fromeither SUZI or ICSI showed any evidence of fetal abnormalities.Pregnancy rate was negatively correlated, with sperm progressionbeing 36% (36/100) if progression was <2 and 19.8% (40/202)if it was 2 (² = 8.99, P < 0.002). ICSI therefore providesa higher number of embryos available for transfer and shouldbe the primary treatment for severe male factor infertility.     

Fertilization and early embryology: Cryopreservation of immature mouse oocytes

Mouse oocytes enclosed in cumulus cells were isolated from antralfollicles at the germinal vesicle (GV) stage. They were storedin straws at – 196°C by a conventional mouse embryofreezing method using dimethylsulphoxide (1.5 M) as the cryoprotectant.Overall survival assessed after removal of the cumulus cellswas 93% (299/320). A significantly greater proportion of freshoocytes remained arrested at the GV stage during culture (11versus 1%), but the rate of maturation to metaphase II was notsignificantly different between frozen and fresh oocytes (83versus 74%). The rate of fertilization in vitro was similarfor frozen and fresh oocytes matured in vitro (70 versus 81%)but significantly less than with mature ovulated oocytes (96%).Fertilization of frozen and fresh oocytes arrested after germinalvesicle breakdown was similar (77 versus 95%. No evidence ofparthenogenetic activation was found in the different groupsafter overnight incubation of metaphase II oocytes. Implantationwas similar for embryos derived from fresh and frozen GV-stageoocytes matured in vitro and mature ovulated oocytes, but theloss of embryos after implantation was significantly higherin the in-vitro matured groups (frozen, 40% and fresh, 46% versus24%). The overall survival of oocytes frozen at the GV stagewas 27%. This compares favourably with the estimated overallsurvival of mature oocytes cryopreserved by a similar procedure.We conclude that the increased post-implantation loss is dueto suboptimal conditions for maturation in vitro rather thanfreezing injury.     

Cryo-thawed embryos obtained from conception cycles have double the implantation and pregnancy potential of those from unsuccessful cycles

BACKGROUND: The purpose of this study was to evaluate the influence of fresh IVF/ICSI cycle outcome on the prognosis of the related frozen embryo replacement (FER) cycle. METHODS: 459 FER cycles, involving 2049 cleavage stage embryos with no or up to 10% fragmentation, were performed for which the outcome of the fresh cycle was recorded. The cycles were divided into two groups; group A included cycles in which cryopreserved embryos were obtained from fresh cycles in which conception occurred. Group B were cycles in which cryopreserved embryos originated from unsuccessful fresh cycles. RESULTS: Groups A and B were comparable with respect to mean (+/- SD) age at cryopreservation (33 +/- 3.9 versus 33.2 +/- 4 years, P = not significant), mean number of oocytes retrieved and fertilized normally in the fresh cycle (11 +/- 5.2 versus 11.2 +/- 4.8, P = not significant) and mean age at the cryo-thawed transfer (34.5 +/- 4.2 versus 33.9 +/- 4 years, P = not significant). No significant difference was found between the two groups with regard to mean number of embryos cryopreserved (6.5 +/- 3.9 versus 6.2 +/- 3.6) and subsequently thawed (4.5 +/- 2.5 versus 4.5 +/- 1.8) per cycle and number of cryo-thawed embryos transferred per cycle (2.0 +/- 0.7 versus 2.1 +/- 0.8). However, the implantation rate per transferred embryo in group A was double that in group B (23 versus 11.2%, P < 0.0001). Moreover, the clinical pregnancy and ongoing pregnancy rates per cycle were significantly higher in group A compared with group B (34.8 and 27.3% versus 15.6 and 13.1%, P < 0.0001 and P = 0.0003 respectively). The difference in FER cycle outcome could not be explained by confounding variables. CONCLUSIONS: After thawing, cryopreserved embryos originating from conception IVF/ICSI cycles achieve double the implantation and pregnancy rates of those obtained from unsuccessful cycles.     

Infertility: Ultrasonic monitoring during replacement of frozen/thawed embryos in natural and hormone replacement cycles

We evaluated the results of cryopreserved/thawed embryo replacement(FER) to determine if the outcome following transfer in a naturalcycle in a defined group was different to that from a hormonereplacement cycle, and also to assess vaginal ultrasonographicfeatures that assist in predicting the timing of the transfer.At the London Fertility Centre, 149 consecutive FER cycles werestudied retrospectively. Women with proven ovulation and regularcycles were included during natural cycles (n = 77). The hormonereplacement cycle group included women with anovulation, irregularcycles and older women (n = 72). In the natural cycle group,transfer was performed following positive urinary luteinizinghormone (LH) surge and confirmation of ovulation by ultrasonography.With the hormone replacement therapy group, gonadotrophin-releasinghormone analogue was used to induce pituitary down-regulation,oestradiol valerate was supplemented followed by regular ultrasoundmonitoring, and FER 2 days following the initiation of progesterone,which was started once adequate endometrial development wasnoticed on ultrasonography. The pregnancy and ongoing/deliveryrates were analysed in relation to the treatment cycle, age,number and quality of embryos transferred. Ultrasonographicfeatures were examined to evaluate their relationship with theoutcome of treatment. The results showed that no differenceexisted between natural and hormone replacement cycles in pregnancyrates per cycle (26 and 25%), ongoing/delivery rate (20.8% inboth groups), and implantation rate (10.3 and 10.6%). Pregnancyrates were not influenced by the number of embryos transferred,stage at which the embryos were cryopreserved, or whether theywere extra embryos from in-vitro fertilization/embryo transfer,or gamete intra-Fallopian transfer. The pregnancy rate was low(7.4%) if the embryos had less than three blastomeres and ifthe fragmentation was >50% (0% pregnancy rate). With hormonereplacement cycles, age did not influence the outcome, and women40 years and older had a pregnancy rate of 29.4% per cycle.No pregnancies resulted in the natural cycle group if the maximumfollicular diameter was > 22 mm before ovulation. When poorendometrial development was noted (thickness < 8 mm and gradeC) no pregnancy resulted from FER in natural or hormone replacementcycles. The pregnancy rates were higher when the endometriumwas 8 mm thickness and grade B (42.4%) or grade A (21.2%). Weconcluded that FER outcomes in natural cycles were similar tothose arising with hormone replacement therapy provided goodselection criteria were used, and vaginal ultrasonography canassist in timing the day of replacement and identify cases tobe cancelled before the transfer.     

The value of intrauterine insemination with washed husband's sperm in the treatment of infertility

Twenty-nine infertile couples were treated by intrauterine insemination(IUI)of washed sperm from a sub-fertile husband (n = 16), incases of gynaecological (n = 3), combined (n = 4) or idiopathic(n = 6) infertility; 116 treatment cycles redted in 11 ongoingpregnancies. Between 0.25 and 0.45 ml of capacitation medium,containing at least 500 000 pretreated spermatozoa, were inseminated.Pretreatment of first split fractions was performed by centrifugationand swimming up of motile spermatozoa. The pregnancy per cycleindex (P/C) for IUI was 9.5% for a total of 37.9% of all couplestreated achieving pregnancy. These results suggest a substantialbenefit compared with a calculated six months' cumulative pregnancyrate of 4.2% independent of treatment, for this infertile population.The value of IUI in selected cam of infertility seems obviousbut needs further investigation.     

Comparison of clinical outcome after cryopreservation of embryos obtained from intracytoplasmic sperm injection and in-vitro fertilization

The impact of intracytoplasmic sperm injection (ICSI) on cryopreservedzygotes and embryos was evaluated by comparing embryo survivaland implantation between embryos derived from ICSI and thosederived from standard insemination procedures. The study includedpatients whose excess zygotes and embryos were cryopreservedbetween September 1993 and December 1994 and who subsequentlyunderwent a frozen embryo transfer. Embryo survival, clinicalpregnancy rates per transfer and pregnancy outcome were compared.Three hundred and thirty eight cryopreservation cycles, duringwhich 1471 embryos were cryopreserved, were included in thisstudy. Of those, 961 were derived from oocytes fertilized byinsemination in vitro and 510 were derived from oocytes fertilizedby ICSI. A total of 690 of the embryos (451 in the inseminationgroup and 239 in the ICSI group) have since undergone a thawcycle. The embryo survival rates were similar between the twogroups (70.5 and 73.2%, insemination and ICSI respectively)and were not significantly affected by the stage at cryopreservation.There was no significant difference in pregnancy rates per transfer(31.8 and 32.3%), the preclinical pregnancy loss rate (16.7and 23.8%), or the clinical miscarriage rate (16.7 and 23.8%)between the insemination and the ICSI groups respectively. Itis concluded that ICSI does not have an adverse impact on thesurvival and successful implantation of cryopreserved and thawedembryos.     

Human preimplantation embryo cryopreservation: selected aspects

This report describes the results of cryopreserving human preimplantation zygotes and cleaved embryos (2-4 cells) in our in-vitro fertilization programme. Cryopreserved zygotes and cleaved embryos resulted in similar post-thaw survival rates (74.8 versus 70.9%). Pregnancy rates per retrieval cycle (RC) and embryos transferred per pregnancy for frozen-thawed zygotes versus frozen-thawed cleaved embryos were 21.8 versus 11.5% (P less than 0.2) and 12.6 versus 17.5 (P less than 0.2), respectively. Pregnancy rates increased significantly for both fresh (P less than 0.0005) and frozen-thawed (P less than 0.05) embryos as the number of embryos replaced per transfer increased from one to three or more. Frozen-thawed embryos resulted in multiple implantation rates per transfer of 25 compared to 6.4% (P less than 0.1) for fresh embryos when two embryos were replaced. Pregnancy rates were reduced for fresh (P less than 0.05) and frozen-thawed (P less than 0.1) embryos obtained from patient retrieval cycle numbers greater than 3. The method of follicular stimulation during the retrieval cycle did not affect frozen-thawed embryo survival rates. There was no difference in pregnancy rates from frozen-thawed embryos replaced during natural or clomiphene citrate transfer cycles. Patients with cryopreserved embryos had cumulative pregnancy rates of 37.1% (66/178) compared to 23.5% (110/468) (P less than 0.01) for patients with no embryos cryopreserved; cryopreservation of preimplantation embryos is a reliable therapeutic procedure that enhances achievement of pregnancy through in-vitro fertilization.     

Intrauterine insemination

Fifty-six couples with infertility due either to subnormal sperm(n = 40), hostile cervical mucus (n = 5) or idiopathic infertility(n = 11), were treated with intrauterine insemination of washedsperm. A total of 78 treatment cycles were completed. Nine pregnanciesresulted from these insemination cycles, giving an overall pregnancyrate of 8.3% per treat ment cycle. Eight pregnancies occurredIn the andrologic group after 56 treatment cydes. One pregnancywas established in the patient group with idiopathic infertilityafter 15 treatment cycles, while no pregnancy occurred in thepatient group with infertility due to cervical mucus hostility.The mean number of years of infertility in the couples conceivingfollowing treatment was 7 years (range 3–11). The spontaneouspregnancy rate in this patient group is low. The data obtainedin this study suggest that in selected patients intrauterineinsemination will result in an acceptable pregnancy rate. Thereis a need for a randomized prospective study designed to comparethe efficacy of intrauterine insemination with that of alternativetreatment modalities.     

Endocrinology: Progesterone alone versus progesterone combined with HCG as luteal support in GnRHa/HMG induced IVF cycles: a randomized clinical trial

Two different regimens of luteal support in gonadotrophin hormone-releasinghormone (GnRH) analoguefhuman menopausal gonadotrophin (GnRHa/HMG)-inducedin-vitro fertilization cycles (IVF) were compared in a randomizedclinical trial. After embryo transfer, either vaginal progesteronealone was administered (n=89, P group), or a combination ofvaginal progesterone and human chorionic gonadotrophin (n=87,P/HCG group). The primary aim of this study was to assess theeffect of the different regimens of luteal support on the pregnancyrate. The secondary aim was to compare oestradiol and progesteroneconcentrations in the luteal phase between the two groups, andassess their effect on the pregnancy rate. A clinical pregnancyrate of 15% was found in the P/HCG group in comparison with26% in the P group (odds ratio 0.49; 99% confidence interval:0.18–1.3). The luteal serum oestradiol and progesteronevalues in the P/HCG group were significantly higher when comparedwith the P group on the 6th, 9th and 12th day after oocyte retrieval(Wilcoxon P<0.001). In accordance with the high oestradiolconcentrations, more cases of ovarian hyperstimulation syndrome(OHSS) were found in the P/HCG group. Oestradiol values on the9th day after oocyte retrieval, presumably the day of implantation,appeared to be higher in women who did not become clinicallypregnant. We conclude that vaginal progesterone alone providessufficient luteal support in GnRHa/HMG induced IVF cycles. Thecombination of vaginal progesterone and HCG as luteal supportleads to significant high luteal oestradiol and progesteroneconcentrations. But a high concentration of oestradiol seemsto have a deleterious effect on the implantation process, resultingin a low pregnancy rate.     

Cryopreservation of human embryos and oocytes

The success rate of human embryo cryopreservatlon depends ontechnical and embryonic parameters. First of all, the cryoprotectantcan affect embryo survival as we found by comparing two freeze-thawprocedures using propanediol (PROH) (1.5 mol) alone or withsucrose (0.1 mol). Embryo survival was significantly enhancedwith sucrose (62 versus 32%). Embryo quality is another majorparameter involved in the success of freezing; the rates ofpositive survival were found to be 67% for morphologically normalembryos versus 49% for embryos with fragments (P < 0.001).The efficiency of embryo cryopreservatlon in an IVF programmecould be estimated in 1986: a woman with extra embryos, storedafter transfer of 3–4 fresh embryos (16% of all cydes),can expect a 22% pregnancy rate per transfer of fresh embryosand a 32% pregnancy rate per collection after transfer of thestored eggs. A comparative study of the cryopreservability ofimmature or mature oocytes was performed in humans. Human oocyteshave a low survival rate (36%) whatever the cryopreservationprotocol or the initial maturation stage. Immature human oocytescould survive freezing and thawing, mature and be fertilizedin vitro, but with a very low efficiency.     

Fertilization and early embryology: Parthenogenetic activation of human oocytes following cryopreservation using 1, 2-propanediol

Fresh and aged human oocytes were cryopreserved using 1, 2-propanediol(PROH). After thawing, the oocytes were cultured for 20 h andexamined for parthenogenetic activation using light microscopyand an ultraviolet DNA stain. Control fresh or aged oocytesand oocytes exposed to PROH without cryopreservation were alsoexamined for activation. No control oocytes were observed toactivate spontaneously (n = 43) and parthenogenetic activationwas not induced by exposure to PROH alone (n = 26). In bothfresh and aged cryopreserved oocytes, 27 and 29% of the oocytesrespectively were activated, and these proportions were significantlyelevated compared with the controls (P < 0.01). Althougha similar rate of activation was observed for the cryopreservedfresh and aged oocytes, the form of parthenogenetic activationvaried between these two types of oocyte. A single pronucleuswas observed in 18% of the fresh and 5% of the aged cryopreservedoocytes. In contrast, the presence of two or more pronucleiwas observed in 0% of the fresh and 19% of the aged cryopreservedoocytes.     

Comparison of concurrent pregnancy rates for in-vitro fertilization-embryo transfer, pronuclear stage embryo transfer and gamete intra-Fallopian transfer

Concurrent pregnancy and implantation (sacs/embryos transferred)rates were compared for 84, 77 and 49 cases of in-vitro fertilization–embryotransfer (TVF–ET), pronuclear stage embryo transfer (PROST)and gamete intra-Fallopian transfer (GIFT), respectively. Allcases reported occurred during an 18-month interval since theinitiation of PROST by our programme. Leuprolide acetate wasused with follicle stimulating hormone and human menopausalgonadotrophin for follicular stimulation of all but donor oocytecases (n = 9). Clinical pregnancy (per transfer) and implantationrates were significantly higher (P < 0.03) for PROST (52.4%,20.2%) in comparison with IVF–ET (26.9%, 11.4%). Ratesfor GIFT (48.9%, 18.4%) were not significantly higher (P = 0.10,0.14) than for IVF—ET. This was probably due to the lowernumber of GIFT than PROST procedures performed. The total pregnancyrate for GIFT (biochemical, ectopk and clinical combined) wassignificantly greater (P < 0.05) than for IVF—ET. Pregnancyand implantation rates for PROST and GIFT were similar. Theseresults support the use of PROST rather than IVF—ET forall cases in which the woman has one functional Fallopian tube.Furthermore, to maintain equivalent rates of pregnancy withPROST and GIFT, it is suggested that GIFT should not be usedfor cases of male-factor infertility without first documentingnormal rates of in-vitro fertilization with PROST.     

Human embryo cryopreservation, extrinsic and intrinsic parameters of success

Freezing and thawing (F-T) was applied to 490 early human embryosusing propanediol as cryoprotectant. The survival rate of embryosfrozen with propanediol alone did not exceed 31% (26/83). Thecombination of propanediol and sucrose, however, significantlyincreased the percentage of surviving (248/407 = 61%) and intact(188/407 = 46%) embryos and seemed to enhance embryo viabilityas suggested by the implantation rate (14.5 versus 8%) without,however, any statistical significance. Embryo survival, butnot viability, was correlated with morphological features, whereasneither the age of embryos (1, 2 or 3 days post-insemination)nor the segmentation stage (regular or intermediate) were involvedin F—T ability. Thirty-eight F—T embryos implantedwhen replaced in uterro, representing 8% of all F—T embryosand 14% of the F—T replaced embryos. The pregnancy rateper transfer reached 19% (35/185) and was identical to the pregnancyrate per transfer of fresh embryos (253/1149 = 22%). In oocytedonation, too, embryo freezing did not impair the pregnancyrate (25%). In spontaneous cycles, synchronous transfer gavebetter results than asynchronous transfers (20 versus 10%),but spontaneous cycles had no significant advantage (16% pregnaocy/transfer)as compared to stimulated (26%) and artificial (27%) cycles.