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.     

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.     

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.     

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.     

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.     

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.     

Effect of developmental stage of embryo at freezing on pregnancy outcome of frozen-thawed embryo transfer

BACKGROUND: The study aim was to investigate the impact of the developmental stage of embryos on pregnancy outcome of frozen embryo transfer (FET). METHODS: The survival rates of embryos after thawing and pregnancy outcome following FET were compared retrospectively between three cryopreservation strategies utilizing either zygote, day 2 or day 3 embryo freezing. RESULTS: A total of 4006 embryos was analysed in 1657 thaw cycles. The highest (P < 0.0001) survival rate (all cells survived) was observed for zygotes (86.5%), followed by day 2 (61.7%) and day 3 (43.1%) embryos. FET was performed in 1586 (95.7%) of all thaw cycles, resulting in overall clinical pregnancy and implantation rates of 20.7 and 14.2% respectively. The delivery rate per transfer was 16.5%, and live birth rate per transferred embryo 11%. There were no significant differences in clinical pregnancy, implantation, delivery and birth rates between frozen zygote, day 2 and 3 embryo transfers. However, an elevated miscarriage rate was observed in the day 3 group (45%) compared with zygotes (21.3%; P = 0.049) and day 2 embryos (18.3%; P = 0.004). The overall efficacy of FET (birth rate per thawed embryo) was 7.3%. The efficacy was lower in day 3 group (4.2%) than in the zygote (7.1%; P = 0.082) and day 2 (7.6%; P = 0.027) groups. CONCLUSIONS: The developmental stage of embryos at freezing has a profound effect on their post-thaw survival, but seems to have little effect on rates of clinical pregnancy, implantation, delivery and birth after FET. The elevated miscarriage rate for day 3 frozen embryo transfers may be caused by damage during freeze-thaw procedures. The low survival rate and elevated miscarriage rate were both responsible for a reduced overall efficacy for day 3 FET when compared with zygotes and day 2 embryos.     

Influence of the time interval between embryo catheter loading and discharging on the success of IVF

BACKGROUND: To ascertain the influence of the duration of the 'interval loading-discharging embryos' (ILDE) on the results of embryo transfer. METHODS: The population under study consisted of 450 consecutive fresh embryo transfers. ILDE was measured in all transfers. Pregnancy and implantation rates were analyzed. RESULTS: Conceptional cycles had a lower (mean +/- SD) ILDE than non conceptional cycles (53.5 +/- 43.6 s vs 63.7 +/- 49.3). When only easy transfers--defined as those not requiring cervical tenaculum--were considered, similar differences were observed. The following pregnancy rates were obtained according ILDE duration: 38.9% (ILDE < 30 s), 33.2% (ILDE 31-60), 31.6% (ILDE 61-120) and 19.1% (ILDE > 120) (P < 0.05). When only easy transfers were considered, similar results were obtained: 40.0%, 33.3%, 32.0% and 19.4%, respectively. Similar results were observed regarding implantation rates regarding the whole population (21.2%, 15.4%, 15.9% and 9.4%, respectively; P < 0.01) as well as when only easy transfers were considered. CONCLUSIONS: ILDE duration is a prognostic factor of pregnancy rate and of implantation rate in IVF. The longer the ILDE duration, the lower the pregnancy and implantation rates. The decrease in pregnancy and implantation rates is gradual until an ILDE of 120 s, and decreases sharply afterwards. It is recommended to speed up the embryo transfer process, wherever possible. ILDE > 120 s carries a poor prognosis and should, when possible, be avoided.     

Best site for embryo transfer: the upper or lower half of endometrial cavity?

BACKGROUND: The objective of the present study was to determine the importance of the site of embryo transfer (upper or lower half endometrial cavity) on implantation and clinical pregnancy rates. METHODS: A total of 400 transfers guided by ultrasound were randomly assigned to two groups according to the distance between the uterine fundus and the catheter tip at the time of embryo placement. Group I (n = 200) consisted of transfers corresponding to a distance of < 50% of the endometrial cavity length (ECL), i.e. transfer in upper half of the cavity; and group II (n = 200) consisted of transfers corresponding to a distance of > or = 50%, of the ECL, i.e. transfer in lower half of cavity. The Student's t-test, Mann-Whitney test and Fisher's exact test were used where appropriate. RESULTS: The general characteristics of the study population and the main transfer cycle characteristics had an equal distribution (P > 0.05) between groups I and II. No significant difference in implantation or pregnancy rates was observed between groups I and II. CONCLUSION: The implantation or pregnancy rates were similar whether the embryos were deposited in the upper or lower half of the endometrial cavity.     

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.     

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.     

Ultrasound-guided embryo transfer does not offer any benefit in clinical outcome: a randomized controlled trial

BACKGROUND: Ultrasound-guided embryo transfer (ET) is widely suggested as a standard clinical practice that improves overall embryo implantation and pregnancy rates. Various studies of this issue suffer from methodological pitfalls, so that a randomized controlled trial, which overcomes these problems, might be valuable. METHODS: Three hundred women aged <40, who underwent fresh ET, were included in this randomized, double-blind controlled trial. The K-J-SPPE echo tip soft catheter was used for the ultrasound-guided ET and the traditional K-Soft catheter for ETs not using ultrasound. One experienced operator performed all ETs. The primary study outcome was overall pregnancy rate (defined as the number of positive hCG results per transfer). RESULTS: No significant differences between groups were found regarding baseline patient and embryological characteristics, except for male factor and unexplained infertility (higher in the blind and ultrasound-guided ET group, respectively, P < 0.05). Overall pregnancy rates were 53.3 and 51.3% in the ultrasound-guided and blind ET group, respectively. Two ectopic pregnancies were reported in each group. Difficulty in cervical negotiation did not differ between the two groups. CONCLUSIONS: In patients undergoing ET by an experienced operator, ultrasound guidance did not provide any benefit in terms of overall clinical pregnancy and embryo implantation rates.     

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

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

Early embryo cleavage is a strong indicator of embryo quality in human IVF.

BACKGROUND: In order to decrease multiple birth rates without decreasing birth rates overall, it is important to increase the capability of selecting the most optimal embryos for transfer. It has been shown that human embryos which cleave early, i.e. complete the first mitotic division within 25-27 h post insemination, provide higher pregnancy and implantation rates. METHODS AND RESULTS: In this prospective study, an evaluation of 10 798 scored embryos showed that early cleavage resulted in a significantly higher proportion of good quality embryos compared with late cleavage (62.5 versus 33.4%, P < 0.0001). When examining both day 2 and day 3 transfers together, early-cleaving embryos (306 transfers) gave rise to significantly higher rates of pregnancy/transfer (40.5 versus 31.3%, P = 0.0049), implantation (28.0 versus 19.5%, P = 0.0001) and birth/ongoing pregnancy (34.3 versus 24.0%, P = 0.0009) than did late-cleaving embryos (521 transfers). A stepwise logistic regression of all data showed that the total number of good quality embryos and female age were independent predictors of both pregnancies and birth. For intracytoplasmic sperm injection (ICSI) embryos, early cleavage was found to be an independent predictor of birth. CONCLUSIONS: Early embryo cleavage is a strong biological indicator of embryo potential, and may be used as an additional embryo selection factor for ICSI embryos.     

Vitrification of human blastocysts with the Hemi-Straw carrier: application of assisted hatching after thawing

BACKGROUND: The present study was undertaken to examine the usefulness of both vitrification and assisted hatching (AH) on blastocysts that originate from embryos showing different qualities during their cleavage stage. METHODS: A total of 281 blastocysts were vitrified (93 vitrification-warming cycles) in a mixture of ethylene glycol-dimethylsulphoxide-Ficoll and sucrose using the Hemi-Straw (HS) carrier system. After warming, AH using the partial dissection technique was performed in 36 cycles. RESULTS: After warming and culture for 24 h, a total of 168 blastocysts (60%) was suitable for embryo transfers and a total of 25 ongoing pregnancies (27%) was obtained. Forty-nine transfers of 96 no-AH blastocysts and 36 transfers of 72 AH blastocysts resulted in an implantation rate of 13 and 22% respectively (P < 0.05). The percentage of transfers with at least one hatching blastocyst was significantly higher after application of AH (69 versus 33%) (P < 0.001). In all, 73 and 38% of blastocysts showing respectively optimal and non-optimal embryo development during the early stage were available for transfer (P < 0.001). Consequently, implantation rates of 19 and 6% were obtained after transfers of blastocysts showing respectively optimal and poor embryo development. CONCLUSIONS: Artificial opening of the zona pellucida after warming of vitrified blastocysts significantly improved the rate of transfers with hatched blastocysts and the implantation and pregnancy rates. The percentage of blastocysts that survived the HS vitrification procedure and were available for embryo transfer is related to their previous developmental quality.     

Elective transfer of one embryo results in an acceptable pregnancy rate and eliminates the risk of multiple birth.

To avoid multiple pregnancies without compromising pregnancy rates (PR) is a challenge in assisted reproduction. We have compared pregnancy results among 74 elective one-embryo transfers (group 2) and 94 transfers where only one embryo was available (group 1). All the fresh embryo cycles during 1997 in two clinics in Helsinki were analysed, and cumulative PR among these couples after frozen-thawed embryo transfers up to June 1998 were counted. In group 2, where at least two embryos were available for transfer, and only one was transferred on day 2 or 3, the PR per embryo transfer was 29.7%. In group 1, the PR per embryo transfer was 20.2%. In group 2, the cumulative PR after frozen-thawed embryo transfers was 47.3% per oocyte retrieval. Over the same time, 742 two-embryo transfers were carried out. The PR per embryo transfer was 29.4% in these subjects, but 23.9% of these pregnancies were twins. The implantation rates, as well as the PR, were highest when the embryos were at the four- to five-cell stage on day 2 (35.8 versus 9.7% compared with the two- to three-cell stage, P < 0.001) or at the six- to eight-cell stage on day 3 (45.5%). The PR per embryo transfer was higher when a grade 1 or 2 embryo was transferred compared with a grade three embryo (34. 0 and 26.7% versus 8.8% respectively, P < 0.05). In women 35 years or younger, the PR per elective one-embryo transfer was 32.8%. The corresponding figure in women older than 35 years was 18.8%. On the basis of these results, elective one-embryo transfer can be highly recommended, at least in subjects who are younger than 35 years of age, and who have grade one or grade two embryos available for transfer.     

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.     

Day 3 embryo transfer with combined evaluation at the pronuclear and cleavage stages compares favourably with day 5 blastocyst transfer

BACKGROUND: The respective advantages of day 3 and day 5 embryo transfer are a matter of debate. Previous comparisons did not include pronuclear stage zygote scoring and cumulative success rates (fresh and cryopreserved embryos). METHODS: Patients were randomized prospectively for day 3 or day 5 embryo transfer. Day 3 embryos were selected for transfer and cryopreservation by using combined evaluation at the pronuclear and cleavage stages. RESULTS: There was no difference between day 3 and day 5 fresh embryo transfers as to the rates of pregnancy (58 versus 62%), clinical pregnancy (56 versus 58%), delivery (50 versus 48%), implantation (35 versus 38%) and birth (33 versus 36%) rates. The corresponding values for cryopreserved embryo transfers were also similar. However, day 3 embryo transfer compared favourably with day 5 transfer when the pregnancy (90 versus 66%), clinical pregnancy (85 versus 62%) and delivery (77 versus 52%) rates were calculated per oocyte recovery attempt. CONCLUSIONS: With a selected population of good prognosis patients and our embryo selection criteria, the implantation potential of day 3 and day 5 embryos is equal. Per oocyte recovery attempt, day 3 transfer is more clinically efficient than day 5 transfer, but at least one transfer of cryopreserved embryos is necessary to manifest this superiority.     

Limiting the number of injected oocytes to three impairs ICSI outcomes in patients with nonobstructive azoospermia

BACKGROUND: Since March 2004, only a maximum of three oocytes were allowed to be subjected to ICSI at one time in Italy. A previous study failed to show an impact of this restriction on fresh embryo transfer outcomes. The objective of this study was to compare ICSI outcomes before and after this restriction in patients with nonobstructive azoospermia. METHODS: Patients underwent testicular sperm extraction followed by ICSI. Biological (fertilization rate and the percentage of good-morphology zygotes and embryos) and clinical (clinical pregnancy and implantation rates) outcomes of the last 100 ICSI attempts before the restriction and outcomes of the first 100 ICSI attempts after the restriction were compared. RESULTS: Despite comparable fertilization rates (58.8% versus 59.2%; P > 0.05), there was a significant decrease in the percentage of good-morphology zygotes (41.1% versus 88.4%; P < 0.05) and embryos (36.7% versus 74.0%; P < 0.05) in the cohort of embryos transferred, clinical pregnancy rate (22.7% versus 42.4%; P < 0.05) and cumulative pregnancy rate from fresh and frozen embryo transfers (22.7% versus 53.5%; P < 0.05) after the restriction. CONCLUSION: The oocyte number restriction reduces dramatically the chance of achieving a clinical pregnancy in cases of nonobstructive azoospermia.