Ultrasound-guided embryo transfer: a prospective randomized controlled trial.

BACKGROUND: Recent reports suggested that ultrasound guidance during embryo transfer might improve the pregnancy rate. METHODS: A prospective randomized controlled trial was performed to compare embryo transfer under ultrasound guidance versus the clinical touch method. A total of 800 embryo transfers was studied; 400 were randomized to ultrasound-guided transfers and 400 were randomized to the clinical touch group. Of these, 441 were fresh cycles and 359 were frozen-thawed cycles. RESULTS: The clinical pregnancy rate was 26.0% in the ultrasound-guided group and 22.5% in the clinical touch group; the difference was not statistically significant. The ongoing pregnancy rate was 23.5% in the ultrasound-guided group compared with 19.0% in the clinical touch group and the difference was again not statistically significant. The implantation rate was slightly higher in the ultrasound-guided group (15.3%) than the clinical touch group (12.0%) (P = 0.048). There were no differences in the incidences of ectopic pregnancy, miscarriage and multiple pregnancy between the two groups. CONCLUSIONS: A significant improvement in implantation rate was observed following the use of ultrasound guidance during embryo transfer. The extent of improvement in the pregnancy rate may depend on the specific techniques and methods of embryo transfer used in individual centres.     

Effect of using an echogenic catheter for ultrasound-guided embryo transfer in an IVF programme: a prospective, randomized, controlled study

BACKGROUND: Recent evidence showed that ultrasound-guided embryo transfer significantly increases successful implantation compared to the clinical touch method. It has been postulated that new echodense catheters which are more readily detectable by ultrasound may refine transfer techniques even more, thus improving IVF outcome. METHODS: A prospective, randomized, controlled trial comparing IVF outcome for women undergoing embryo transfer under ultrasound guidance by a single healthcare provider with random assignment according to a computer-generated randomization table to either standard soft Wallace catheter (standard catheter group, n=95) or the new echogenic soft Wallace catheter (echogenic catheter group, n=98). RESULTS: The use of the echodense catheter facilitated catheter identification under ultrasound, and thus the duration of the embryo transfer procedure since the loaded catheter was handed to the physician and up to embryo discharge was significantly shorter in the echogenic catheter group as compared with the standard catheter group. There were 39 and 53 clinical pregnancies in the standard catheter (41%) and echogenic catheter (54.1%) groups, respectively. This was not statistically significant (P=0.08) according to the OR (0.6) and CIs (0.33-1.04). However, twin pregnancy rate was significantly increased (P<0.01) with the use of the new catheter which was the underlying source for obtaining significant increase in implantation rate in this group (37.1%) as compared with the standard catheter group (23.2%). CONCLUSION: This pilot study suggests that the use of the echogenic Wallace catheter simplifies ultrasound-guided embryo transfer but not definite benefit in terms of pregnancy rates was obtained. In contrast, the use of the new catheter was associated with a significant increase in the number of twin pregnancies.     

The usefulness of ultrasound guidance in frozen-thawed embryo transfer: a prospective randomized clinical trial

BACKGROUND: Recent randomized controlled trials have shown that implantation and pregnancy rates were improved with ultrasound-guided embryo transfer compared with clinical touch in fresh IVF cycles associated with supraphysiological ovarian steroid levels. However, the usefulness of ultrasound guidance in frozen-thawed embryo transfer where potential hormonal influences are lacking has not been appropriately investigated. METHODS: A total of 184 consecutive patients undergoing thawed embryo transfer cycles with hormone replacement under pituitary suppression were randomized by computer-generated randomization table to two study groups: 93 had ultrasound-guided (group 1) and 91 had clinical touch (group 2) embryo transfer. RESULTS: There was equal distribution between the two study groups with respect to the main demographic and baseline characteristics of the patients as well as the characteristics of both prior IVF cycles from which embryos were generated and cryopreserved-thawed embryo transfer cycles. However, both pregnancy and implantation rates in group 1 (34.4 and 19.8% respectively) were significantly higher than the corresponding values (19.7 and 11.9%) in group 2. CONCLUSIONS: Ultrasound guidance in frozen-thawed embryo transfer significantly increases pregnancy and implantation rates.     

Embryo transfer under ultrasound guidance improves pregnancy rates after in-vitro fertilization

Between October 1998 and January 1999, we examined the influence of ultrasound guidance in embryo transfer on pregnancy rate in 362 patients from our in-vitro fertilization (IVF)-embryo transfer programme. These patients were prospectively randomized into two groups: 182 had ultrasound-guided embryo replacement, and 180 had clinical touch embryo transfer. There were no statistically significant differences between the two groups with respect to age, cause of infertility and in the characteristics of the IVF cycle. The pregnancy rate was significantly higher among the ultrasound-guided embryo transfer group (50%) compared with the clinical touch group (33.7%) (P < 0.002). Furthermore, there was also a significant increase in the implantation rate: 25.3% in the ultrasound group compared with 18.1% in the clinical touch group (P < 0.05). In conclusion, ultrasound assistance in embryo transfer significantly improved pregnancy and implantation rates in IVF.     

Ultrasound measurement of the uterocervical angle before embryo transfer: a prospective controlled study

BACKGROUND: The study aim was to determine whether moulding the embryo transfer catheter according to the uterocervical angle measured by ultrasound could improve pregnancy and implantation rates. METHODS: Patients were alternately allocated to one of two groups. In the ultrasound-guided group (n = 320), the catheter was moulded according to the uterocervical angle measured by abdominal ultrasound. In controls (n = 320), embryo transfer was performed using the "clinical feel" method. RESULTS: Moulding the embryo transfer catheter according to the uterocervical angle significantly increased clinical pregnancy [(OR = 1.57, 95% CI (1.08-2.27)] and implantation rates [(OR = 1.47, 95% CI (1.10-1.96)] compared with the "clinical feel" method. It also significantly reduced difficult transfers [(OR = 0.25, 95% CI (0.16-0.40)] and blood during transfers [OR = 0.71, 95% CI (0.50-0.99)]. Patients with large angles (>60 degrees ) had significantly lower pregnancy rates compared with those with no angle [OR = 0.36, 95% CI (0.16-0.52)]. CONCLUSIONS: Moulding the embryo transfer catheter according to the uterocervical angle measured by ultrasound increases clinical pregnancy and implantation rates and diminishes the incidence of difficult and bloody transfers.     

Ultrasound-guided embryo transfer and the accuracy of trial embryo transfer

BACKGROUND: Studies have suggested that ultrasound-guided embryo transfer (UG-ET) may improve the outcome in IVF; however, several factors may account for the improvement in pregnancy rate. This study examines the use of ultrasound to determine the accuracy of trial transfer (TT) in preparation for ET. METHODS: Sixty-seven consecutive patients prospectively underwent UG-ET over a 2 month period. Total cavity length by US was compared with the length noted by TT. A difference of > or = 1 cm was considered significant. All embryos were placed within 1-2 cm of the fundus by US. RESULTS: Twenty patients (29.9%) had a difference of > or = 1 cm and 13 patients (19.4%) had a difference of < or = 1.5 cm. Patients with a difference of > or = 1 or > or = 1.5 cm had a significantly greater depth at transfer (P < 0.001) and uterine cavity length (P < 0.001) when compared with patients without a difference. Clinical pregnancy, implantation, delivery and overall miscarriage rates did not differ between patients with a difference of > or = 1 or > or = 1.5 cm versus no difference. There were no ectopic pregnancies. CONCLUSIONS: Nineteen percent of patients had a discrepancy of > or = 1.5 cm and approximately 30% had a difference of > or = 1 cm from TT at UG-ET, suggesting a benefit to UG-ET. A large prospective randomized trial comparing UG-ET with blind transfer is required to assess further if UG-ET should be used in all cases of ET.     

The influence of the depth of embryo replacement into the uterine cavity on implantation rates after IVF: a controlled, ultrasound-guided study

BACKGROUND: Traditionally, embryo transfer after IVF has been performed blindly and placing the embryos approximately 1 cm below the fundal endometrial surface. However, it has been suggested that transferring embryos rather lower in the uterine cavity or high in the uterus may improve implantation rates. Nevertheless, there has not yet been a controlled trial to prove this theory. This prospective randomized study investigates the influence of the depth of embryo replacement on the implantation rate after embryo transfer carried out under transabdominal ultrasound guidance. METHODS: A total of 180 consecutive patients undergoing ultrasound-guided embryo transfer were randomized to three study groups according to the distance between the tip of the catheter and the uterine fundus at the moment of the embryo deposition in the lumen of the endometrial cavity: group 1: 10 +/- 1.5 mm; group 2: 15 +/- 1.5 mm; group 3: 20 +/- 1.5 mm. RESULTS: There was equal distribution between all three study groups regarding the main demographic and baseline characteristics of the patients, ovarian response, oocyte retrieval and IVF outcome, as well as the characteristics of embryo transfer and luteal phase support. The position of the catheter tip in relation to the fundal endometrial surface in groups 1 (10.2 +/- 0.9 mm), 2 (14.6 +/- 0.7 mm) and 3 (19.3 +/- 0.8 mm) was significantly different. Implantation rate was significantly higher (P < 0.05) in groups 2 (31.3%) and 3 (33.3%) compared with group 1 (20.6%). CONCLUSIONS: The depth of the embryo replacement into the uterine cavity may influence implantation rates, and thus it should be considered as an additional procedure among factors recently proposed as associated with successful embryo transfer after IVF.     

Transvaginal ultrasound-guided embryo transfer improves pregnancy and implantation rates after IVF.

BACKGROUND: Attempts are constantly being made to improve clinical pregnancy rates after IVF and embryo transfer. Since November 1998, we have gradually been adopting transvaginal ultrasound guidance during embryo transfer. We retrospectively examined the efficacy of this method on pregnancy and implantation rates. METHODS: The results of 846 cycles from our IVF-embryo transfer programme were analysed and comparisons were made between those carried out using ultrasound guidance and those by the clinical touch method. RESULTS: Higher pregnancy and implantation rates (28.9 and 15.2% respectively) were found in the group using the transvaginal ultrasound guidance during embryo transfer compared with those in the group using the clinical touch method (13.1 and 7.0% respectively). The differences were statistically significant (P < 0.01). There was no significant difference in ectopic pregnancy rates between the two groups. CONCLUSION: The use of transvaginal ultrasound-guided embryo transfer significantly improved both pregnancy and implantation rates. Although technically difficult, we suggest its use may maximize the chances of achieving a successful pregnancy outcome.     

Embryo transfer: ultrasound-guided versus clinical touch.

In this prospective control study, the pregnancy and implantation rates were compared between ultrasound-guided and clinical touch uterine embryo transfers. In addition, a subset of patients was sought that would particularly benefit from embryo transfer under ultrasound guidance. A total of 187 patients (93 ultrasound and 94 clinical touch) was enrolled. Allocation was random and depended on whether their embryo transfers were done during the 1 h each day in which the ultrasound was available. Pregnancy and implantation rates of 37.8 and 20.4% respectively were achieved when ultrasound was used, compared with 28.9 and 16.2% respectively with clinical touch. This difference was not statistically significant. There was no significant difference in the pregnancy rate when the number of embryos transferred was controlled. Older women (>/=37 years old) had an apparently higher pregnancy rate (38.1 versus 20.4%; not significant) with ultrasound guidance during embryo transfer. In the subgroup where the clinician rated the transfer procedure as difficult, there appeared to be a substantial improvement in the pregnancy rate in the group that used ultrasound (54.5 versus 10.0%; not significant). Although our results were not statistically significant, we believe that ultrasound-guided embryo transfers should be used in clinically difficult embryo transfers and in older women, as it appears to improve the pregnancy rate over clinical touch transfers.     

A randomized controlled trial of a soft double lumen embryo transfer catheter versus a firm single lumen catheter: significant improvements in pregnancy rates

BACKGROUND: Embryo transfer has changed little since originally described in 1978. Clinicians rate the type of catheter used as the third most important variable in embryo transfer, but there are no adequately powered randomized trials. We compared the clinical pregnancy rates with the single lumen catheter (TCC) and the double lumen catheter (CC) in a randomized single blind trial. METHODS: A total of 650 cycles of women from the Adelaide University reproductive medicine units in Australia were included in this trial. Patients were <40 years of age undertaking IVF and embryo transfer. Exclusion criteria were: known uterine abnormality, day 3 FSH >10 IU/l, previous difficult embryo transfer and pre-implantation genetic diagnosis. Cycles were randomized from numbered sealed envelopes immediately prior to embryo transfer with stratification for fresh or frozen cycles. RESULTS: There was a significantly higher pregnancy rate in the group treated with the CC compared with the TCC catheter [29.6 versus 20.5% per embryo transfer, odds ratio (OR) = 1.63 (95% confidence interval: 1.14-2.30), P = 0.0076]. The point estimate for the OR was similar for fresh and frozen cycles. CONCLUSIONS: The pregnancy rate was increased by 50% and this justifies the increased cost of the soft double lumen catheter and the training of clinical staff required.     

GnRH agonist protocol administration in the luteal phase in ICSI-ET cycles stimulated with the long GnRH agonist protocol: a randomized, controlled double blind study

BACKGROUND: GnRH agonist administration in the luteal phase was reported to beneficially affect the clinical outcome of intracytoplasmic sperm injection (ICSI) and embryo transfer (ET) cycles. This double blind, randomized, placebo controlled trial evaluates whether a single dose GnRH agonist administered 6 days after ICSI increases ongoing pregnancy rates following ET in cycles stimulated with the long GnRH agonist protocol. METHODS: Five hundred and seventy women undergoing ET following controlled ovarian stimulation with a long GnRH agonist protocol were included. In addition to routine luteal phase support with progesterone, women were randomized to receive a single 0.1 mg dose of triptorelin or placebo 6 days after ICSI. Randomization was done on the day of ET according to a computer generated randomization table. Ongoing pregnancy rate beyond 20th week of gestation was the primary outcome measure. The trial was powered to detect a 12% absolute increase from an assumed 38% ongoing pregnancy rate in the placebo group, with an alpha error level of 0.05 and a beta error level of 0.2. RESULTS: There were 89 (31.2%) ongoing pregnancies in the GnRH agonist group, and 84 (29.5%) in the control group (absolute difference +1.7%, 95% confidence interval -5.8% to +9.2%). Implantation, clinical pregnancy and multiple pregnancy rates were likewise similar in the GnRH agonist and placebo groups. CONCLUSIONS: Single 0.1 mg triptorelin administration 6 days after ICSI following ovarian stimulation with the long GnRH agonist protocol does not seem to result in an increase >or=12% in ongoing pregnancy rates.     

Ultrasound-guided embryo transfer improves pregnancy rates and increases the frequency of easy transfers

BACKGROUND: Recent reports have suggested that ultrasound (US) guidance during embryo transfer might improve pregnancy rates. METHODS: A prospective randomized (computer-generated random table) trial was performed to compare embryo transfer under abdominal US guidance (n = 255 women) with clinical touch embryo transfer (n = 260). RESULTS: The clinical pregnancy rate was 26.3% (67/255) in the US-guided transfer group compared with 18.1% (47/260) in the clinical touch transfer group (P < 0.05). The implantation rate was 11.1% (100/903) in the US group compared with 7.5% (66/884) in the clinical touch group (P < 0.05). US-guided transfer was associated with a decrease in the difficulty of the transfers: 97% of transfers were easy in the US-guided group compared with 81% in the clinical touch group (P < 0.05). CONCLUSIONS: US-guided embryo transfer increased pregnancy and implantation rates in IVF cycles, as well as the frequency of easy transfers. It is suggested that the decrease in cervical and uterine trauma can play a role in the increase in pregnancy rates associated with US-guided transfer. It is recommended that embryo transfer should be performed under US guidance.     

A prospective randomized study to assess the benefit of partial zona pellucida digestion before frozen-thawed embryo transfers

BACKGROUND: Assisted hatching (AH) in fresh embryo transfer (ET) could be associated with increased implantation rates. However, very few prospective randomized studies have specifically addressed the issue of AH during frozen-thawed embryo transfers (FET) cycles, those that have reported controversial results. The aim of this study was to evaluate the benefit of an enzymatic zona pellucida treatment of frozen-thawed embryos before transfer. METHODS: This was a prospective study including 125 non-donor FET cycles from 125 infertile couples. FETs were randomly allocated into AH group (n = 61, embryos pretreated with pronase 5 IU/ml for 1 min at 37 degrees C) or control group (n = 64, untreated embryos). Zona pellucida thickness was measured for each transferred embryo. The main outcome parameters were clinical pregnancy and implantation rates. RESULTS: The two groups were comparable regarding mean women's age, duration and indications of infertility, IVF outcome after fresh ETs, numbers and quality of fresh and frozen embryos, frozen-thawed embryo survival rates and blastomeres survival indexes. Despite a statistically significant decrease of zona pellucida thickness after pronase treatment [(mean +/- SD) 18.5 +/- 2.25 versus 14.5 +/- 2.75 microm; P < 0.0001], implantation (9.6 versus 9.2%) and clinical pregnancy rates (18.0 versus 17.2%) were not statistically different after FETs, with a similar mean number of embryos transferred between AH and control groups, respectively. CONCLUSION: Within the constraints of our protocol, partial enzymatic digestion of zona pellucida by pronase was not related with any benefit of the FET outcome especially concerning the implantation ability of frozen-thawed embryos.     

Ultrasound-guided soft catheter embryo transfers will improve pregnancy rates in in-vitro fertilization

Attempts to improve clinical pregnancy rates after in-vitro fertilization (IVF) and embryo transfer are constantly being made. Two changes in technique of embryo transfer of potential clinical importance were evaluated over two contiguous time periods in order to observe any corresponding change in clinical pregnancy (CP) rate per transfer: (i) embryo transfer catheter; (ii) ultrasound guidance. Catheter choices were hard: Tefcat, Tom Cat, or Norfolk; or soft: Frydman or Wallace. Ultrasound visualization was considered to be excellent/good when the catheter could be followed from the cervix to the fundus by transabdominal ultrasound with retention of the embryo-containing fluid droplet; fair/poor if visualization could not document the sequence of events. Embryo transfers were performed in 518 cycles. CP rates per transfer using soft and hard catheters was 36 and 17% (P < 0.000) respectively. CP rates per transfer for transfers performed with and without ultrasound guidance were 38 and 25% (P < 0.002) respectively. A statistically significant difference was also noted when visualization ranks were compared. CP rates per transfer in all excellent/good ultrasound-guided transfers was 41.5 versus 16.7% for fair/poor transfers (P < 0.038). In conclusion, performance of embryo transfer with a soft catheter under ultrasound guidance with good visualization resulted in a significant increase in clinical pregnancy rates.     

Ultrasound-guided embryo transfer maximizes the IVF results on day 3 and day 4 embryo transfer but has no impact on day 5

BACKGROUND: The use of ultrasound-guided embryo transfer has been reported to affect success rates in some centres but not others. In a prospective study, we examined the influence of ultrasound guidance in embryo transfer performed on different days after oocyte retrieval. METHODS: Two different methods of embryo transfer were evaluated in 1069 consecutive transfers. The ultrasound-guided embryo transfer was used in 433 cases, whereas 636 embryo transfers were performed with the tactile assessment ('clinical feel') method. RESULTS: Ultrasound-guided embryo transfer yielded a higher overall pregnancy rate than the 'clinical feel' approach, 47 versus 36% (P < 0.001). This difference was statistically significant where embryos were transferred after 3 or 4 days of culture, 45.9 versus 37.1% (P = 0.001) and 42.3 versus 27% (P = 0.035) respectively but not significant (P = 0.112) on day 5 embryo transfer (56.3 versus 45.7%). Likewise, the implantation rate was significantly different between the two groups on day 3 and 4 embryo transfer, 23.3 versus 15.8% (P < 0.01) and 21.6 versus 15.7% (P < 0.05%) respectively but no statistical difference was noted on day 5 embryo transfer, 26.7 versus 23.6%. CONCLUSION: Ultrasound assistance in embryo transfer on day 3 and 4 significantly improved pregnancy rates in IVF but had no impact on day 5.     

A randomized double-blind controlled study of the efficacy of laser-assisted hatching on implantation and pregnancy rates of frozen-thawed embryo transfer at the cleavage stage

BACKGROUND: Assisted hatching (AH) in fresh embryo transfer (ET) cycles increases the implantation and pregnancy rates, especially in women with a poor prognosis, repeated implantation failures and in older women. Little information exists in the literature regarding the role of AH in frozen-thawed embryo transfer (FET) cycles. METHODS: Embryos were cryopreserved at the cleavage stage. On the day of FET, 160 patients were randomized according to a computer-generated randomization list in sealed envelopes into the AH group and the control group. The patients and the clinicians were blinded to the group assigned. In the AH group, the outer half of the zona pellucida over a quarter of the diameter of zona was removed using a 1480 nm non-contact laser. RESULTS: The two groups were comparable in terms of demographic characteristics, ovarian response of the stimulated cycle and quality of fresh and frozen-thawed embryos. No differences in implantation, pregnancy and multiple pregnancy rates were found between the two groups. There was a non-significant trend of a higher implantation rate in the AH group when the zona thickness was > or = 16 mm. CONCLUSION: Laser AH did not improve the implantation rate of FET cycles and should not be performed routinely in all frozen-thawed embryos at the cleavage stage.     

The impact of the embryo transfer catheter on the pregnancy rate in IVF

BACKGROUND: The aim was to assess whether the type of embryo transfer set used for embryo transfer affects the ongoing pregnancy rate in IVF. METHODS: The TDT set was compared with the K-soft 5000 in a large, prospective, randomized study. Patients were randomized moments before transfer by drawing a consecutively numbered, sealed, opaque envelope indicating the catheter to be used. RESULTS: 2059 embryo transfers in 1296 patients were analysed. The ongoing pregnancy rate was significantly higher in the K-soft group. If the first transfer of a patient (n = 1296) within this study period was analysed, the ongoing pregnancy rates were 27.1 versus 20.5% (P = 0.006). If the analysis is limited to patients that underwent their very first transfer ever (n = 607), the ongoing pregnancy rates were 30.3 versus 20.0% (P = 0.003) in favour of the K-soft. CONCLUSION: We conclude from these data that the type of embryo transfer set used for embryo transfer does affect the ongoing pregnancy rate and that the impact of the variable transfer catheter on the ongoing pregnancy rate increases when the a priori chance of pregnancy increases.     

The presence of blood in the transfer catheter negatively influences outcome at embryo transfer

BACKGROUND: Embryo transfer (ET) influences pregnancy rates in patients undergoing assisted reproduction. Data are conflicting as to which variables affect ET success. This study examines variables that may affect outcome after ET in assisted reproductive technology patients who had high-quality embryos transferred. METHODS: Over a 23 month period, 669 consecutive cycles were examined. Only patients having grade I and grade II embryos, or blastocyst transfers, were included in this retrospective analysis. A total of 584 consecutive cycles met study criteria. At the time of ET, the following variables were recorded: aborted first attempt at ET; presence of blood and/or mucus in or on the transfer catheter after ET; ease of ET as judged by provider; need for mock embryo transfer immediately before the actual transfer and retention of embryos in the transfer catheter. These variables were retrospectively analysed for their impact on implantation rate (IR) and clinical pregnancy rate (CPR). RESULTS: There were 290 gestations (49.7% CPR). Multiple attempts at ET, subjective difficulty of ET, performance of a sham pass immediately prior to embryo transfer, and presence of mucus on or in the catheter did not affect the CPR or IR. No difference was noted in the mean age of patients having or lacking any of these factors. There was a significant association between the presence of blood on or in the catheter and decreased IR (P = 0.015) and CPR (P = 0.004). Retained embryos also decreased IR (P = 0.03). Multivariable analysis confirmed that the presence of blood on the transfer catheter was the most important of these transfer characteristics in predicting IR (P = 0.042) and CPR (P = 0.018). CONCLUSIONS: These results suggest that when only high-grade embryos or blastocysts are transferred, the presence of blood on the catheter is associated with decreased IR and CPR in assisted reproduction.     

A prospective, randomized study: day 3 versus hatching blastocyst stage

BACKGROUND: Recently, advances in human IVF-embryo transfer (ET) have been reported using sequential media and blastocyst stage ET. In our previous report, using a prospective, randomized study, no advantage was found using the blastocyst stage ET compared with day 3 ET. This study was performed in order to evaluate implantation and pregnancy rates of hatching blastocyst stage ET compared with conventional day 3 ET. METHODS AND RESULTS: A total of 480 patient cycles were evaluated using a prospective, randomized study. The pregnancy rate and implantation rate were compared between the day 3 ET (n = 240) and hatching blastocyst stage ET (Hat ET; n = 240). The Hat ET group had a pregnancy rate of 29.3% (55 out of 188) and an implantation rate of 21.4% (67 out of 313). The day 3 ET group had a pregnancy rate of 29.2% (70 out of 240) and an implantation rate of 19.1% (93 out of 488). In the Hat ET group, the pregnancy rate, implantation rate and ongoing pregnancy rate of day 5 ET and day 6 ET were all higher than the respective rates in the day 7-9 ET group. CONCLUSION: We found that the pregnancy rate and implantation rate of ET with hatching stage blastocysts had no advantage compared with the conventional day 3 ET.     

Tubal embryo transfer in cynomologus monkeys: effects of hyperstimulation and synchrony

To date the main limitation of in-vitro fertilization–embryotransfer (IVF–ET) programmes is that transcervical transferof embryos results in a rate of low implantation. On the otherhand, the technique of gamete intra-Fallopian transfer (GIFT)does not contribute to information on oocyte fertilization rates,and the time of oocyte exposure to sperm may be limited. Thedevelopment of ultrasonically guided follicular aspiration willallow transfer of embryos generated in vitro to the Fallopiantubes performing only one surgical procedure in the process.We have perfonnd 25 intra-tubal embryo transfers in the cynomolgusmonkey (Macaca fascicularis). Ovarian stimulation, folliularaspiration and IVF procedures have been reported previouslyby Balmaceda. ETs were performed via laparotomy. Embryos atthe 2-, 4- or 9-cell stage were loaded into a tom-cat catheterin 5 ?l of culture medium and delivered to the mid-ampullaryportion of the tube. Seven ETs performed during stimulated cyclesresulted in one pregnancy, and 18 ETs performed in synchronizedrecipients resulted in six pregnancies. Ten ETs were performed0–24 h, eight performed 24–48 h and seven performed72–110 h after follicular aspiration or ovulation, andresulted in 4, 3 and 0 pregnancies respectively. Our resultsdemonstrate that intra-tubal embryo transfer can result in normalintra-uterine pregnancies and suggest that both ovarian stimulationand cycle synchronization affect the probability of embryo implantation.