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PubMed2004

Elective single-embryo transfer versus double-embryo transfer in in vitro fertilization.

BACKGROUND: The risks of premature birth and perinatal death are increased after in vitro fertilization. These risks are mainly due to the high incidence of multiple births, which relates to the number of embryos transferred. METHODS: We performed a randomized, multicenter trial to assess the equivalence of two approaches to in vitro fertilization with respect to the rates of pregnancy that result in at least one live birth and to compare associated rates of multiple gestation. Women less than 36 years of age who had at least two good-quality embryos were randomly assigned either to undergo transfer of a single fresh embryo and, if there was no live birth, subsequent transfer of a single frozen-and-thawed embryo, or to undergo a single transfer of two fresh embryos. Equivalence was defined as a difference of no more than 10 percentage points in the rates of pregnancy resulting in at least one live birth. RESULTS: Pregnancy resulting in at least one live birth occurred in 142 of 331 women (42.9 percent) in the double-embryo-transfer group as compared with 128 of 330 women (38.8 percent) in the single-embryo-transfer group (difference, 4.1 percentage points; 95 percent confidence interval, -3.4 to 11.6 percentage points); rates of multiple births were 33.1 percent and 0.8 percent, respectively (P<0.001). These results do not demonstrate equivalence of the two approaches in rates of live births, but they do indicate that any reduction in the rate of live births with the transfer of single embryos is unlikely to exceed 11.6 percentage points. CONCLUSIONS: In women under 36 years of age, transferring one fresh embryo and then, if needed, one frozen-and-thawed embryo dramatically reduces the rate of multiple births while achieving a rate of live births that is not substantially lower than the rate that is achievable with a double-embryo transfer.

Adult↗
PubMed2006

Towards defining parameters for a successful single embryo transfer in frozen cycles.

BACKGROUND: Twin pregnancies in IVF should be avoided by transferring embryos one at a time, even for frozen cycles. In this study, we investigated the effect of blastomere lysis and cleavage in singleton frozen embryo transfer (sFET) cycles. Outcomes were compared with the transfer of two embryos in frozen transfer cycles (dFET). METHODS: A retrospective analysis was performed on 891 FET cycles, involving 404 sFET and 487 dFET cycles. RESULTS: Overall, in sFET cycles, the pregnancy and implantation rates were 8.9 and 8.7%. When blastomere lysis was more than 25% but no greater than 50%, the pregnancy and implantation rates were 3.2%. If blastomere lysis was greater than 50% there were no pregnancies. If blastomere lysis was less than 25%, but with no cleavage, the pregnancy and implantation rates were 4.1%. The results significantly improved (P = 0.007) in the group with less than 25% lysis, when cleavage occurred. The pregnancy and implantation rates for this group were 17.3 and 16.6%. This was not significantly different from unselected two embryo transfers (22 and 12.7%,P = 0.2 and 0.19, respectively). There were 21 twins with dFET (19.6% of pregnancies) and none in sFET. CONCLUSION: Both blastomere lysis and cleavage affect the outcome in sFET. To avoid the risk of twins, sFET should be considered when the embryo shows less than 25% blastomere lysis and at least one blastomere cleaves.

Adult↗
PubMed1993

Effects of strain and embryo transfer model (embryos from one versus two donor does/recipient) on results of cryopreservation in rabbit.

Differential effects of 2 transfer models for normal thawed embryos of 1 donor doe were studied on the offspring rate and their embryo survival at birth from 3 selected rabbit strains (SY and SB: synthetic strains, NZ: New Zealand White). Morulae were obtained 64-66 h post-coitum from 93 adult does treated with 25 IU of hCG (SY:36, NZ:27, SB:30). Morphologically normal morulae were frozen in the presence of 1.5M DMSO and stored in liquid nitrogen. Normal thawed embryos were transferred into the oviducts of synchronized recipient does of the same strain 48 h after being injected with 25 IU of hCG (SY:28, NZ:21, SB:24). Each recipient received embryos from 1 (single transfer) or 2 different donor does (double transfer). Significant differences were observed in the post-thawing percentage of normal embryos between strains (SY:95 +/- 1% and SB:85 +/- 3%, P < 0.05; NZ: ,91 +/- 2%). After transfer, no significant differences were observed in pregnancy rate and offspring rate between the transfer models, whereas significant differences were only found in survival rate when all transfers were analyzed (double: 24 +/- 4% vs single: 14 +/- 3%, P < 0.05). An effect of strain was detected in the pregnancy rate (NZ: 33% vs SB: 71%, P < 0.05; SY: 61%) and in the survival rate per donor doe on pregnant recipient doe (SY: 42 +/- 5 vs SB: 19 +/- 5, P < 0.05; NZ: 34 +/- 7%). These results suggest a differential embryo sensitivity with respect to their genetic origin in both the freezing-thawing and transfer procedures.

Animals↗
PubMed2000

Pregnancy rates after embryo transfer depend on the provider at embryo transfer.

OBJECTIVE: To evaluate the effect of individual providers on pregnancy outcome after embryo transfer. DESIGN: Retrospective data analysis. SETTING: University-based tertiary-care assisted reproductive technology program with 10 physician-providers. PATIENT(S): Six hundred and seventeen women who underwent 854 fresh embryo transfers between January 1996 and January 1999. INTERVENTION(S): Pregnancies after embryo transfer were recorded for each provider. MAIN OUTCOME MEASURE(S): Establishment of a clinical pregnancy. RESULT(S): Three hundred ninety-three clinical pregnancies resulted from 854 embryo transfers, for an overall clinical pregnancy rate of 46.0% per embryo transfer. Three hundred forty-seven (40.6%) pregnancies were ongoing. The clinical pregnancy rate varied significantly between providers: for example, 17.0% (47 transfers) vs. 54.3% (57 transfers) (P<.05). Similarly, the ratio of high-grade embryos required to produce a gestational sac differed between providers. The number or quality of embryos transferred did not differ significantly. CONCLUSION(S): Significant differences were observed in pregnancy rates after embryo transfer done by different providers, suggesting that embryo transfer technique may influence pregnancy outcome in assisted reproductive technology.

Adult↗
PubMed1981

Artificial induction of twinning in cattle by means of supplemental embryo transfer.

The induction of twins by surgical and nonsurgical transfer was performed 6 - 8 days after Artificial Insemination (A.I.) in a total of 142 cows. Of the 47 heifers, which received surgically transferred embryos, 32 (68%) became pregnant. Of the 95 cows, which received nonsurgically transferred embryos, 58 (61,6%) became pregnant. A total of 90 (63.5%) of the recipient animals became pregnant. Up to date 64 recipients have calved; twins have resulted in 40 and 48,2% resp, from surgical and nonsurgical inductions. Out of a total of 64 calvings 29 (45,3%) were twins, and of these 38% were males, 27% were females, and 34% were mixed births. Female - calves resulted in freemartinism. There was no increase in the incidence of either retained placenta or dystocia. The induction of twinning by means of embryo transfer can be regarded as a useful method for the increase in the reproductive performance cattle.

Journal Article↗
PubMed1998

Reducing multiple pregnancies by restricting the number of embryos transferred to two at the first embryo transfer attempt.

Though the multiple pregnancy rate in in-vitro fertilization-embryo transfer must be reduced, strict and uniform regulation of the number of embryos transferred may make it impossible for women with little natural fecundity to carry children. We therefore restricted the number of embryos per transfer. In the first half of the observation period (n = 100), we limited the number of embryos transferred to three regardless of the number of previous transfers. In the second half (n = 137), we strictly regulated the number of embryos transferred to two at the first attempt and three in the second and later attempts. The multiple pregnancy rate per pregnancy was significantly lower (P < 0.005) in the second period (20.4%) than in the first period (52.9%), while the clinical pregnancy rate and the implantation rate per transfer were similar in both observation periods. 60.7% (17/28) of the multiple pregnancies arose from the first embryo transfer attempt, and 17.9% (5/28) of them arose from a second attempt. The 18 multiple pregnancies in the first period involved six sets of triplets, while the 10 multiple pregnancies that arose in the second period all involved twins. The implantation rate per transfer at the first attempt was significantly higher than that at the second or later attempts. The criterion for determining the number of embryos transferred should be simple to minimize errors of judgement. We believe that our method of restricting the numbers of embryos transferred may be one method of reducing multiple pregnancies without eliminating the possibility of having children for women with low fecundity.

Adult↗
PubMed1991

Embryo transfer as a means of controlling the transmission of viral infections. XIII. Failure to transmit foot-and-mouth disease virus through the transfer of embryos from viremic donors.

A total of 436 embryos/unfertilized ova was collected from 30 foot-and-mouth disease (FMD) viremic cattle; 106 of these embryos/ova were from eight donors that had FMD virus in their reproductive tracts. The 436 embryos/ova were washed and then either assayed in cell culture or intradermally in steer tongues or transferred to recipients. Foot-and-mouth infectivity was not found to be associated with any of the embryos/ova assayed in cell culture or intradermally. The 149 embryos transferred produced two abortions, five sets of twins born prematurely, and 15 normal calves. All of the recipients and all of the calves remained FMD-seronegative.

Journal Article↗
PubMed2007

The pre-cycle blind mock embryo transfer is an inaccurate predictor of anticipated embryo transfer depth.

PURPOSE: To assess if the uterine cavity depth measured by a blind pre-cycle mock transfer changes after gonadotropin stimulation. METHODS: This is a retrospective cohort study at an academic IVF program involving 128 infertility patients. The main outcome measures were uterine cavity depth measured at the blind pre-stimulation mock transfer and the ultrasound-guided embryo transfer. RESULTS: A >or= 1 cm increase in uterine cavity depth was found in 57.9% of the patients. The mean pre-cycle blind mock transfer uterine depth significantly differed from the mean uterine depth measured at embryo transfer. Based on the mock transfer, the anticipated embryo transfer depth was significantly less than the actual ultrasound-guided embryo transfer depth. CONCLUSION: Uterine depth significantly differed between the blind pre-cycle mock transfer measurement and the ultrasound-guided embryo transfer measurement. The mock transfer may predict a difficult embryo transfer but it is an inaccurate predictor of the final embryo transfer depth.

Cohort Studies↗
PubMed2001

Evaluation of the embryo transfer procedure proposed by the International Embryo Transfer Society as a method of controlling vertical transmission of Neospora caninum in cattle.

OBJECTIVE: To evaluate efficacy of embryo transfer into seronegative recipients, using the procedure proposed by the International Embryo Transfer Society (IETS), for preventing vertical transmission of Neospora caninum in cattle. DESIGN: Prospective clinical trial. ANIMALS: 87 recipient cows and heifers and their embryo transfer calves from 22 donors originating from 9 dairy herds. PROCEDURE: Neospora caninum serologic status of donors and recipients was determined before collection and transfer of embryos. Viable embryos were washed and treated with trypsin. Recipients in experimental groups A (n = 50) and B (29) were seronegative and received embryos from seropositive and seronegative donors, respectively. Recipients in group C (n = 8) were seropositive and received embryos from seronegative or seropositive donors. Antibody titers against N caninum were determined monthly during pregnancy in recipients and in calf blood samples collected at birth. Tissues collected from stillborn calves and aborted fetuses were analyzed histologically and by immunohistochemical (IHC) methods. RESULTS: 76 calves and 11 fetuses and stillborn calves were examined. All calves from groups A and B were seronegative (n = 70) or lacked evidence of infection by use of tissue analysis (9). In group C, 5 of 6 calves were seropositive at birth, and IHC results were positive for 1 of 2 calves. Vertical transmission rate was significantly lower in groups A and B (0%) than in group C (75%). CONCLUSION AND CLINICAL RELEVANCE: Embryo transfer into seronegative recipients, using the procedure proposed by IETS, is an effective way to prevent vertical transmission of N caninum. Results provide support for pretransfer testing of all embryo transfer recipients.

Animals↗
PubMed2004

Exposure to warmer postoperative temperatures reduces hypothermia caused by anaesthesia and significantly increases the implantation rate of transferred embryos in the mouse.

Embryo transfer (ET) is among the key factors determining the overall efficiency of transgenic technology in the mouse. A successful ET depends among other factors on the quality of the transferred embryos, foster mothers and anaesthetic reagents and on the transfer techniques. Anaesthesia-caused deaths and suboptimal ET procedures are factors which reduce the success of transgenic experiments and mouse colony maintenance. Here we compared the effects of two anaesthetic reagents-a ketamine/xylazine combination, and tribromoethanol (Avertin)-on the rates of implantation and development to term of mouse zygotes transferred into the oviducts of CD-1 foster mothers, and evaluated whether hypothermia caused by anaesthetics after the ET operation could be overcome by postoperative incubation of the foster mothers. We established two experimental groups of fosters, one of which was kept at room temperature (RT, 21 degrees C) with the other in an incubator (33 degrees C) overnight after ET. Rates of implantation, resorption and development to normal fetuses were evaluated by sacrificing the foster mothers on the 15th day of their pregnancy. Our results showed that regardless of the anaesthetic reagents used, the rates of implantation and of development to normal fetuses can be significantly improved by exposing the foster mothers to warmer temperatures (33 degrees C) immediately after the ET operation. These results may have important implications in increasing the success rate of ET with micromanipulated embryos.

Anesthetics↗
PubMed1999

Comparison of pronuclear stage embryo transfer and in vitro fertilization-embryo transfer following intracytoplasmic sperm injection.

To determine whether the mode of embryo transfer (PROST vs IVF) affected the outcome in intracytoplasmic sperm injection (ICSI) cycles, 237 ICSI cycles (106 PROST and 131 IVF) were analyzed. Several parameters, including patient age, duration of infertility, amounts of hMG used, number of mature eggs retrieved and injected, fertilization rate, number of embryos transferred, and clinical pregnancy rate, were compared. Most of the variable factors were not significantly different, except the mean numbers of transferred embryos which were significantly higher in the PROST group. The clinical pregnancy rate showed no statistical difference between PROST and IVF cycles (25.5 and 16.8%; p = 0.139). This study suggests that even the pregnancy rate in PROST cycles was slightly higher than IVF cycles, but there was no statistically significant difference between the two groups.

Adult↗
PubMed2005

Single embryo transfer is an option in frozen embryo transfer.

BACKGROUND: A good strategy to decrease multiple pregnancy rate in assisted reproduction technology (ART) is the use of single embryo transfer (SET). METHODS: This retrospective study analysed 1647 frozen embryo transfers carried out during 1998-2003 in Helsinki University Central Hospital; of these, 872 were double embryo transfers (DETs) and 775 SETs. The SET group included 140 (18.1%) elective SETs (eSETs). RESULTS: The yearly rate of SETs in frozen cycles increased from 28 to 66%. Overall, the clinical pregnancy rate per frozen embryo transfer was 30.7% and the delivery rate 22.6%. The delivery rate was significantly higher in DET cryocycles than in SET cryocycles (25.7 versus 19.2%, respectively; P < 0.01). In DET cryocycles, the multiple delivery rate was 21.9%, 10 times higher than that observed in cryocycles with SET (2.0%) (P < 0.0001). When eSET was applied, no difference in delivery rate was observed when compared with cryocycles with DET (28.6 and 25.7%, respectively). CONCLUSIONS: SET can be used in frozen cycles to reduce multiple delivery rates.

Cryopreservation↗
PubMed1997

Embryo transfer as a means of controlling the transmission of viral infections. XV. Failure to transmit bluetongue virus through the transfer of embryos from viremic sheep donors.

The first experiment involved in vitro exposure of clean embryos to bluetongue virus (BTV) while three subsequent experiments involved the collection of embryos from BTV-infected donor ewes and their transfer to disease-free recipients. In Experiment I, 22 embryos/ova were exposed to BTV type 11 (BTV-11) for 1 h, washed 10 times in PBS and assayed in pairs for BTV. All 11 samples were positive for BTV in the 11-d-old embryonated chicken egg (ECE) assay system and 5/11 samples were positive in baby hamster kidney-21 (BHK-21) cells. In Experiment II, 5 donors were infected with BTV type 10 (BTV-10). All embryos were washed 10 times prior to assay or transfer. Thirty-three embryos/ova were assayed in groups of 2 or 3 and none yielded virus in ECE. Two BTV-seronegative recipients each received 6 embryos and a total of 3 lambs free of BTV antibodies were delivered. In Experiments III and IV, a total of 9 donors were infected with BTV-11. All embryos were washed 10 times prior to assay or transfer. Seventy-four embryos/ova were assayed in groups of 2 or 3 and none yielded virus in ECE, while for each experiment, 6 embryos were transferred into 2 BTV-seronegative recipients. The four recipients and their 3 lambs and 2 aborted fetuses were also seronegative for BTV.

Journal Article↗
PubMed2001

The pregnancy rates--a retrospective comparison of tubal and uterine embryo transfers.

Tubal embryo transfer (TET), which involves an embryo transfer via the uterine tube, has a possible advantage over uterine embryo transfer (UET) due to more natural timing of embryo exposure to the uterine cavity. This study was carried out to evaluate the pregnancy rate of TET versus UET. Eight hundred and ninety-seven consecutive patients who underwent embryo transfers from July 1997 to June 1999 in Bielefelder Institut fuer Fortpflanzungsmedizin (BIF.), Germany were included in this study. Two hundred and eighty-six pregnancies were achieved in 167 cases (31.4%) after TET and 119 cases (24.6%) after UET. The abortion rate of the TET group was 12.0 per cent while that of the UET group was 23.3 per cent. Our results showed that TET has a significantly increased clinical pregnancy rate and significantly decreased abortion rate. There is an advantage in transferring embryos to the fallopian tube in infertile couples with male factor infertility and unexplained infertility. We recommend TET as the first choice for embryo transfer in infertile couples with patent fallopian tubes and with no evidence of pelvic adhesion and/or endometriosis.

Abortion, Spontaneous↗
PubMed1996

[Multiple pregnancies prevention in in vitro fertilization: limiting the number of transferred embryos to two maximum?].

The success of an IVF-programme is mainly linked to the number and quality of embryos transferred as well as women's age, but the incidence of obstetrics complications rises significantly with the number of fetuses. Reducing the number of embryos transferred is therefore recommended in order to avoid the medical, social and financial problems associated with multiple births. Present data suggest that, when at least three embryos of good quality are available, the pregnancy rate already reaches its maximum value when two embryos are transferred. A third one merely increases the number of triple pregnancies. Further studies are needed to conclude, especially in the cases of poor quality embryos.

Adult↗
PubMed1999

Transcervical embryo transfer as a risk factor for ectopic pregnancy.

OBJECTIVE: To evaluate the ease and timing of transcervical ET as risk factors for ectopic pregnancy (EP) after IVF. DESIGN: Retrospective study. SETTING: University-based IVF program in the United Kingdom. PATIENT(S): Eighteen consecutively seen patients with an EP after IVF and 314 patients with an intrauterine pregnancy after transcervical ET performed during the same period. INTERVENTION(S): Additional manipulation with a transfer catheter or the use of other instruments to assist transfer. Embryo transfer on day 2 or 3 after oocyte retrieval. MAIN OUTCOME MEASURE(S): Risk factors for EP (day 2 ET, difficult transfer overall and on days 2 and 3, history of tubal subfertility, and previous EP) presented as odds ratios with 95% confidence intervals. RESULT(S): The risk of EP was 2.26 (0.64-8.01) after day 2 ET, 3.91 (1.49-10.23) after difficult ET, 3.88 (1.34-11.24) after difficult ET on day 2, 2.7 (0.20-13.99) after difficult ET on day 3, 5.73 (1.99-16.62) when there was a history of tubal subfertility, and 5.41 (1.96-14.91) when there was a previous EP. CONCLUSION(S): A difficult ET significantly increases the risk of an EP. The risk is particularly high when the patient has a history of tubal damage or previous EP. The timing of ET is important only if the ET is difficult.

Cervix Uteri↗