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PubMed1985

Embryo transfer in sheep under practice conditions.

Embryo transfer was carried out on nine Texel donor ewes, one of them on two occasions, over two breeding seasons (1980 and 1981). The donors were prepared for superovulation on the farm by two different regimens and the recipients were also synchronised on the farm of origin. Surgery was carried out on donors and recipients at a veterinary practice and the techniques of anaesthesia, surgery and embryo transfer are described. Superovulation was variable and more than two ovulations were seen in only four of the 10 ewes. Forty-one corpora lutea were produced by the 10 ewes and 27 embryos were recovered. Twenty-one embryos were transferred to recipients and 14 lambs were produced. All the 10 donors except one produced lambs themselves. The value, economics and welfare aspects of the technique of embryo transfer under practice conditions are discussed and it is concluded that the procedure should not be carried out routinely but reserved for special circumstances.

Animals↗

PubMed1996

Comparison of uterine blood flow characteristics between spontaneous and stimulated cycles before embryo transfer.

The Doppler blood flow characteristics of uterine arteries were evaluated prospectively in 57 patients undergoing embryo transfer. A total of 32 women underwent frozen-thawed (FT) embryo transfer during a spontaneous menstrual cycle (FT-embryo transfer), and 25 patients underwent in-vitro fertilization treatment (IVF-embryo transfer). The endometrial thickness, pulsatility index (PI), maximum peak systolic velocity (MPSV), minimum diastolic velocity (MDV) and flow velocity waveform type of the uterine artery blood flow were assessed with transvaginal colour Doppler ultrasonography before embryo transfer. The mean (SD) endometrial thickness was 9.2 (2.0) mm in FT-embryo transfer patients and 12 (3.4) mm in IVF-embryo transfer patients (P < 0.0003). There were no conception cycles in which the uterine arteries bilaterally had a flow velocity waveform with an absent end-diastolic flow. Compared to spontaneous cycles, the median PI was statistically lower and the MDV was higher in IVF cycles. In contrast, no difference was found in the median MPSV values between the two groups. There was no difference in Doppler velocimetry measurements between the conception and non-conception cycles in either the FT-embryo transfer or the IVF-embryo transfer groups. In conclusion, an inadequate uterine blood flow impaired implantation, while optimum uterine blood perfusion did not necessarily lead to conception.

Arteries↗

PubMed2005

The Holstein cow in embryo transfer today as compared to 20 years ago.

Embryo transfer practice and results were examined over a 20-year period in Holstein cows and heifers within four commercial embryo transfer programs located in different areas of North America. Mean embryo production per collection decreased (P < 0.05) in one program over time, but not in the other three. Changes in the type of cows entering embryo transfer programs, the number of times they were superstimulated and changes in the brands of gonadotropins used for superstimulation all complicated the analysis of embryo production over time. Data reveal higher pregnancy rates (P < 0.001) following transfer of embryos into Holstein heifers than into lactating dairy cows. It is not clear whether pregnancy rates have decreased over time as a result of the change from surgical to non-surgical embryo transfer. In the two programs in which pregnancy rates were analyzed, there was a decrease (P < 0.001) when non-surgical transfers were adopted in one program, while no change occurred in the other. One of the biggest changes in all programs was that more than 50% of embryos recovered from donors are now frozen after collection, whereas the majority were transferred fresh 20 years ago.

Animals↗

PubMed1991

Embryo survival in pseudopregnant and in pregnant but genetically semi-sterile recipients after nonsurgical embryo transfer in the mouse.

A new nonsurgical embryo transfer technique was used in the mouse that yielded survival rates of between 40 and 70% depending on embryo stage and, possibly, on the degree of synchrony between the embryo and recipient. Three variables were tested using this embryo transfer technique: a) pseudopregnant recipients vs pregnant but genetically semi-sterile recipients, b) embryos resulting from superovulation vs embryos from natural ovulation, and c) 12-hour vs 24-hour asynchrony between donors and recipients. None of these variables significantly affected the pregnancy rate or the percentage of transferred embryos developing to term. The pregnancy rates were between 77 and 90% in 6 experimental groups of 8 to 13 females. Survival rates were between 41 and 63% when all recipients were considered and between 53 and 68% when only the pregnant recipients were included. The embryo transfer procedure influenced litter size composition of the endogenous conceptuses of the semi-sterile recipients. Too many females were devoid of these. Recipients of expanded blastocysts had significantly better transfer results than recipients that also received morulae and early blastocysts. It was concluded that the transfer success rates were influenced by the recipients and possibly by their preparation for transfer.

Journal Article↗

PubMed1989

Early, late, and sequential embryo transfer in in vitro fertilization program: a preliminary report.

The timing of ET was evaluated by transferring four embryos at 44 to 48 hours, 68 to 72 hours, or equally dividing and sequentially transferring at 44 to 48 and 68 to 72 hours after insemination. Fifty-one patients were randomly allocated to one of the above protocols. The mean number of blastomeres of embryos transferred at 68 to 72 hours after insemination was significantly (P less than 0.0001) higher than those transferred at 44 to 48 hours. The number of embryos with good morphology was similar in all study groups. The pregnancy rate was similar in the three protocol groups, 53% at 44 to 48 hours, 59% at 64 to 72 hours, and 47% by sequential transfer. There probably is no advantage in delaying the transfer or dividing the embryos into two sequential transfers. It seems that sequential transfer is not associated with any harmful effect.

Adult↗

PubMed1993

Embryonic losses after in vitro fertilization and embryo transfer.

Early loss of embryos is a major problem after in vitro fertilization (IVF) and embryo transfer (ET). Because implantation of the embryo is a precondition for an increasing serum beta-hCG level, the embryonic development cannot be evaluated during the pre- and peri-implantation period. Early pregnancy factor (EPF) is a marker of the development of the embryo before and during implantation. Therefore serum samples of 82 patients were screened for EPF and beta-hCG after IVF/ET. 63% (52/82) of all patients were positive for EPF, 21% (17/82) showed elevated serum beta-hCG levels. Clinical pregnancies occurred in 12 patients (15%) resulting in nine deliveries. After difficult ET EPF turned negative more frequently in the peri-implantation period compared to transfers without problems. Emphasis should be directed towards optimizing the placement of the embryos and towards minimizing the trauma of the uterus.

Abortion, Spontaneous↗

PubMed1990

Effects of age and body mass of recipients on survival of transferred embryos in mice.

To examine the effects of age and body mass of recipients on embryo survival during gestation, ICR embryos were transferred to nulli- or primi-parous females of 4 strains of mice. Out of 530 recipients, 383 (72.3%) produced a litter. Transfer of 3,465 embryos to 383 recipients resulted in production of 1,637 pups born alive, an overall rate of embryo survival of 47.2 +/- 1.1%. Regression analyses revealed that embryo survival decreased in older recipients and increased in heavier recipients. The results were consistent in each parity/strain group and all groups combined.

Age Factors↗

PubMed2006

Frozen embryo transfers: implications of clinical and embryological factors on the pregnancy outcome.

BACKGROUND: Frozen embryo transfers are characterized by impaired pregnancy outcome and increased incidence of pregnancy loss as compared with fresh IVF/ICSI embryo transfers. In this study, we performed a retrospective analysis of clinical and embryological factors that potentially influence the outcome of frozen embryo transfer. METHODS: We reviewed the outcome of 1242 frozen embryo transfers with respect to the age of the woman, the method of fertilization, embryo quality before and after freezing and the number of embryos transferred. RESULTS AND CONCLUSIONS: The pregnancy (positive hCG) and clinical pregnancy rates were 25.8 and 21.1%, respectively. A total of 107 (33.3%) of the 321 pregnancies identified by a positive hCG test miscarried either before (18.4%) or after (15%) the clinical recognition of gestational sac(s). The delivery rate for the frozen embryo transfers analysed was 17.2%. Our data revealed that the delivery rate after frozen embryo transfer was dependent on both the woman's age and the quality of embryos transferred, at the same time being unaffected by IVF/ICSI treatment. In addition, the increased woman's age at IVF/ICSI treatment was identified as the only parameter elevating the biochemical pregnancy rate, whereas the clinical abortion rate was found to be unrelated to the clinical or embryological parameters studied.

Adult↗

PubMed2001

Frozen-thawed embryo transfer: influence of clinical factors on implantation rate and risk of multiple conception.

BACKGROUND: Frozen embryo transfer is an important supplementary procedure in the treatment of infertility. While general information concerning the outcome of frozen embryo transfer has been documented, few studies have addressed the potential of embryo implantation in particular clinical situations. Importantly, the risk of multiple conception following frozen embryo transfer has been poorly documented compared with the information available for fresh embryo transfer. METHODS: This is a retrospective study analysing 3570 frozen embryo transfer cycles (1438 couples) with a view to increasing our understanding of the clinical circumstances that influence the potential for embryo implantation. RESULTS: The overall implantation rate was 9.1%. The characteristics associated with a more favourable implantation rate were the success of the previous fresh embryo transfer cycle, age < 40 years and non-tubal factor aetiology of infertility. Such women had an increased risk of multiple conception. CONCLUSION: Female age, the aetiology of infertility and the outcome of fresh embryo transfer are the most important factors influencing the implantation rate following frozen embryo transfer. A prognostic table has been constructed that may assist with the determination of the optimal number of embryos to be replaced in frozen embryo transfer to provide better individualized counselling and to secure an optimal chance of pregnancy while reducing the risk of multiple conception.

Adult↗

PubMed1991

Using embryo sexing within closed mixed multiple ovulation and embryo transfer schemes for selection on dairy cattle.

Two types of multiple ovulation and embryo transfer schemes that included bull progeny testing were compared. In the juvenile schemes, embryos were collected at 16 to 18 mo of age without sexing, whereas, in the adult schemes, donors were chosen based on their first lactation record, and their embryos were systematically sexed. With the latter schemes, natural calves obtained at the first two calvings could compete with embryo transfer calves to be replacements. The optimal structure of this scheme was derived algebraically for the same number of transferred embryos as in the juvenile schemes. Predicted asymptotic annual genetic gains, after stabilization of genetic parameters taking into account the Bulmer effect, were found to be slightly in favor of the adult schemes for a given set of parameters (overall number of transferred embryos, number of embryos per collection, and embryo survival rate). In the adult schemes, the nucleus sizes were much larger than in the juvenile schemes, which allowed a higher selection differential on male paths, thus compensating for the longer generation interval. Asymptotic rate of genetic gain for Monte Carlo simulations were about 10 and 7% lower for juvenile and adult schemes, respectively, but still higher (20%) than the predicted value for the corresponding conventional scheme. Consequently, adult schemes with embryo sexing can be an efficient alternative to juvenile schemes without embryo sexing.

Animals↗

PubMed1996

Rederivation of mice by means of in vitro fertilization and embryo transfer.

In vitro fertilization and embryo transfer were performed for rederivation of four strains of mice harbouring mouse hepatitis virus (MHV) and/or Pasteurella pneumotropica (P. pneumotropica). Superovulated oocytes were fertilized by preincubated cauda epididymis sperm in vitro. Fertilized eggs at 2-cell stage were transferred into the oviducts of specific pathogen free (SPF) recipients. Microbial examination of sperm and/or oocyte donors verified the presence of P. pneumotropica and/or of antibodies to MHV in all strains, but neither in the recipients nor in the offspring antibodies to MHV could they be detected. The results indicate that an in vitro fertilization-embryo transfer (IVF-ET) system is an effective and simple alternative to cesarean operation in infected mice.

Animals↗

PubMed2004

Single embryo transfer in clinical practice.

The high incidence of multiple pregnancies is the main reason for adverse treatment outcome in assisted reproduction. A good strategy to avoid multiple pregnancies is elective single embryo transfer and cryopreservation of spare embryos. Important factors in an elective single embryo transfer programme are good counselling of the patients and the selection of embryos with high implantation potential. In the infertility clinic at Helsinki University Central Hospital the elective single embryo transfer programme was started in 1997 and in 2000 the transfer policy turned to single embryo transfer as primary option. In 2003 60% of fresh transfers were elective single embryo transfers and 66% of frozen transfers were single embryo transfers. It has been shown that an elective single embryo transfer programme can be adopted in daily practice and that it decreases the multiple pregnancy rate, in our programme to around 7% with acceptable overall pregnancy and delivery rates. In Finland the increased use of single embryo transfer has reduced the proportion of multiple births. Finally, a good cryopreservation programme is essential to achieve a good cumulative delivery rate without multiple pregnancies.

Cryopreservation↗

PubMed2002

A health-economic decision-analytic model comparing double with single embryo transfer in IVF/ICSI.

BACKGROUND: Single embryo transfer (SET) is the sole strategy with which to reduce the incidence of twins following assisted reproductive technology (ART), but SET may increase the number of ART cycles needed per live-born child. Its cost-effectiveness compared with double embryo transfer (DET) is therefore unknown. METHODS: A decision-analytic model comparing SET with DET was developed. Estimates were obtained from literature, national pregnancy registers and local hospital records. A sensitivity analysis was performed, using pregnancy rates from four published studies. The outcome measure was the cost per child born, calculated from IVF procedure-related, pregnancy-related and neonatal care costs. Neonatal mortality and long-term morbidity costs were not taken into account. RESULTS: Independently of the pregnancy rates used, the SET cost per child born was in all instances the same as with DET, varying from EURO= 9520 (SET) versus EURO= 9511 (DET) to EURO= 12254 (SET) versus EURO= 12934 (DET). CONCLUSIONS: More ART cycles are required to obtain the same numbers of children born following SET compared with DET. Because SET allows the avoidance of twins and thus diminishes pregnancy-related and neonatal care costs, there is no difference in the cost per child born between SET and DET. The real advantage of SET is the avoidance of the very high long-term costs resulting from the increased morbidity of twins after birth.

Cost-Benefit Analysis↗

PubMed1989

The influence of oocyte maturity and embryo quality on pregnancy rate in a program for in vitro fertilization-embryo transfer.

An important factor influencing the pregnancy rate after in vitro fertilization-embryo transfer (IVF-ET) appears to be the number of embryos transferred to the uterus. In this study, the influence of oocyte maturity and embryo quality on pregnancy rate was assessed in patients undergoing IVF-ET. Ovarian hyperstimulation was performed by human menopausal gonadotropin (hMG [n = 29]), clomiphene citrate (CC)/hMG (n = 81), and hMG/follicle-stimulating hormone (FSH [n = 13]) protocols. Oocyte maturity was graded on a scale from 1 to 5 based on the morphology of the ooplasm, cumulus mass, corona radiata, and membrana granulosa cells. Embryos were graded according to the symmetry of the blastomeres and the presence or absence of fragmentation. Mature preovulatory oocytes yielded the highest fertilization rates. No differences were found among the protocols in terms of fertilization rate, embryo quality, or pregnancy rate. When all protocols were combined, patients who conceived had a significantly higher number of embryos transferred than those who did not conceive (3.6 +/- 0.1 [mean = SEM] versus 2.7 +/- 0.1). When embryo quality was compared, there was no difference in the number of "B" embryos transferred between patients who conceived and those who did not (1.2 +/- 0.2 versus 1.2 +/- 0.1), but the patients who conceived had significantly more "A" embryos transferred (1.6 +/- 0.3 versus 0.8 +/- 0.1). These data suggest that the treatment protocol did not determine embryo quality. Furthermore, the increase in pregnancy rates seen with an increase in embryos transferred is the result of the transfer of more "A" embryos.

Blastomeres↗

PubMed2003

Impact of transabdominal ultrasound guidance on performance and outcome of transcervical uterine embryo transfer.

PURPOSE: To determine the impact of transabdominal ultrasound guidance on embryo transfer during IVF therapy. METHODS: Retrospective analysis of 823 consecutive embryo transfers. Three hundred and sixty-seven procedures performed with transabdominal ultrasound guidance were compared to 456 cases performed with the "clinical touch" method. RESULTS: Ultrasound-guided embryo transfer yielded higher, but not statistically significant, clinical pregnancy (48% vs. 44%) and implantation rates (22% vs. 20%). The incidence of multiple pregnancies, ectopic and multiple pregnancy rates were similar. The frequency of negative factors typically associated with difficult transfers, such as requirement of use of tenaculum, and presence of blood or mucus in the catheter tip, were significantly lower in the ultrasound-guided group in comparison with the clinical touch group. Ultrasound-guided embryo transfer was associated with a significantly increased easiness of transfer performance; 95% of the transfers were rated as very easy in the ultrasound-guidance group compared to 87% in the clinical touch group. The use of a soft pass catheter was the only variable independently and significantly associated with pregnancy success (odds ratio = 2.74). CONCLUSION(S): Ultrasound-guidance facilitates embryo transfer and in combination with the use of a soft catheter should be implemented to optimize embryo transfer results.

Embryo Transfer↗

PubMed1988

Incidence of abortion in pregnancies after in vitro fertilization and embryo transfer.

Our purpose was to assess factors that are associated with an increased rate of spontaneous abortion in pregnancies initiated by in vitro fertilization. Pregnancies were diagnosed by measurement of serum human chorionic gonadotropin (hCG) 15 days after embryo transfer. Of the 64 women who conceived, 47 delivered term infants, one patient delivered a stillborn at 22 weeks, 14 aborted in the first trimester, and two had pregnancies that implanted in the tube. Abortion rates were similar for women treated with human menopausal gonadotropin (24%; 12 of 54) and those who received clomiphene citrate (12.5%; one of eight). Two patients conceived after treatment with a combination of clomiphene citrate and human menopausal gonadotropin, neither of whom aborted. In 54 patients treated with human menopausal gonadotropin, there were no significant differences in mean maternal age, number of years of infertility before the pregnancy, history of previous pregnancies, amount of human menopausal gonadotropin used to induce ovulation, serum estradiol levels on the day of hCG administration, mean number of follicles, and the mean number of transferred embryos between the group who delivered and the group who aborted. We conclude that none of these factors are associated with increased tendency for fetal loss in our in vitro fertilization program. Beta-hCG levels on day 15 after embryo transfer were significantly lower in the group who aborted than in the group who delivered, and may be predictive of implantation failure.

Abortion, Spontaneous↗

PubMed2004

Rate of abnormalities in lambs from in vitro produced embryos transferred on Day 2 compared with Day 6 postfertilization.

The effect of transferring ovine IVP embryos on Day 2 versus Day 6 postinsemination was investigated. Oocytes were collected from 35 cull ewes and cultured separately for each donor. Embryos were exposed to serum in the maturation and fertilization media, and then cultured in a serum-free SOF system under serum-conditioned silicone oil. Cleaved Day 2 postfertilization embryos were randomly allocated for immediate transfer versus Day 6 transfer. Parturition was induced (with 15 mg dexamethasone) between Days 141 and 143 of pregnancy; those failing to initiate parturition by Day 146 had a Caesarean section. Stillborn lambs and those dying within several days of birth were necropsied. Lambs were weighed at birth; lambs (n = 132) derived from the same flock (from natural breeding or AI) were used as a control. An estimate of the 99th percentile of the normal population was used as the point above which lambs from three litter-size categories were classified as abnormally large (analysis was repeated for 95% confidence and median estimates of this value). Thirty-eight lambs were born from early transfer, 45 from late transfer and 12 from unobserved lambings (parentage could not be determined). Lambs from early transfer were heavier at birth (P = 6.0 x 10 (-11)). The early treatment group had fewer lambs produced per embryo transferred (P = 0.0002), fewer live lambs per embryo transferred (P = 0.00009) and fewer normal lambs per embryo transferred (P= 0.0002). There was an effect of donor on the number of dead lambs per embryo transferred (P = 0.017). The number of dystocias per transfer was not significantly different for early versus late transfer groups. However, the probabilities of survival for cleaved embryos were 27.3% and 13.1% in the early and late transfer treatment, respectively. There were more lambs produced per cleaved embryo with early transfer (P = 0.004) and there was an effect of donor within ram and replicate (P = 0.04) on the number of lambs produced. The odds ratio for early/late treatment was 2.449 with a confidence interval of 1.368-4.382. Day 2 transfer of cleaved embryos did not prevent the production of oversized or abnormal offspring; however, there was an increased chance of a cleaved embryo producing a lamb when transferred on Day 2 rather than Day 6 postfertilization.

Animals↗

PubMed2005

Germfree status of mice obtained by embryo transfer in an isolator environment.

The technique of embryo transfer has been evaluated for the purpose of changing the mouse stocks to a germfree (GF) status. Our results show reproducible and quality-assured conversion of animals to those which are negative for the presence of microorganisms. Rapid and easy access to GF mice is advantageous for studies of selected microflora and their cross-talks with the host, when applying, e.g. genomic, proteomic and metabolic methodology. The study involved embryo transfer in an isolator environment, thereby allowing implantation of cleansed embryos into GF recipients under well-controlled conditions. The recipient females gave birth normally and took care of the offspring as if they were their own pups, thus enhancing the survival rate. Access to full technical resources required to maintain GF isolators are, however, a prerequisite. In this study, we used stainless steel isolators designed by Gustafsson (1959), on which a stereomicroscope was mounted to facilitate embryo transfer inside the isolator. The use of embryo transfer and isolator techniques will facilitate the availability of various mouse mutant models under different gnotobiotic conditions, GF, monoxenic or polyxenic animals, to enable comparison with conventional animals for physiological and pathophysiological studies.

Animals↗