Impact of the size of zona pellucida thinning area on vitrified-warmed cleavage-stage embryo transfers: a prospective, randomized study.

PURPOSE: The aim of this study was to determine if the size of zona pellucida thinning area by laser assisted hatching could affect the rates of pregnancy and implantation for vitrified-warmed embryo transfers at the cleavage-stage. METHODS: A total of 120 vitrified-warmed cleavage-stage embryo transfers were randomly assigned to either quarter or half of zona pellucida thinning group. RESULTS: The rates of clinical pregnancy (46.7 versus 25.0%) and implantation (32.0 versus 16.2%) were significantly greater in the half thinning group than in the quarter thinning group (P = 0.0218 and P = 0.0090, respectively). CONCLUSIONS: The results of this investigation show that, in vitrified-warmed embryo transfers at the cleavage-stage, the size of zona pellucida thinning area by laser assisted hatching impacts the rate of clinical pregnancy and implantation and that half of zona pellucida thinning significantly increases both of these results compared with quarter of zona pellucida thinning.

Case report: successful delivery following the transfer of a human re-vitrified day-7 spontaneously hatched blastocyst developed from vitrified cleaved embryos.

PURPOSE: To report a successful delivery after the transfer of a re-cryopreserved day-7 hatched blastocyst. METHODS AND RESULTS: A 30-year-old woman underwent a long-treatment protocol for ovarian stimulation. Fourteen mature oocytes were obtained, and twelve were fertilized. On day 3, two cleaved embryos were transferred, but no implantation occurred. The remaining embryos were vitrified. Subsequently, two vitrified day-3 embryos were transferred. The woman became pregnant and delivered a healthy baby. Subsequently, two vitrified day-3 embryos were transferred, but no pregnancy occurred. Subsequently, all the remaining vitrified day-3 embryos were cultured. On day 5, no blastocyst was obtained. The remaining embryos were continued to be cultured. On day 7, a hatched blastocyst was obtained and re-vitrified. Subsequently, the re-vitrified day-7 hatched blastocyst was transferred. The woman became pregnant and delivered a healthy female. CONCLUSIONS: The day-7 hatched blastocyst developed from vitrified embryos can be re-vitrified and have pregnancy potential after re-warming.

Perinatal outcomes following transfer of human blastocysts vitrified at day 5, 6 and 7.

Little information is available on perinatal outcome of cryopreserved day-7 blastocyst transfer. In the present report, perinatal outcomes for transfers of cryopreserved blastocysts by a vitrification method were examined with respect to the day of blastocyst expansion among on day 5, 6 or 7 before cryopreservation. We investigated 263 cycles of vitrified-warmed blastocyst stage embryo transfer performed between April 2005 and April 2009, which were reviewed retrospectively. There were 144 cycles with day-5 blastocyst, 100 cycles with day-6 blastocyst, and 19 cycles with day-7 blastocyst transfers. There were no differences among the vitrified day-5, day-6 and day-7 blastocyst transfer groups regarding mean number of embryos transferred, pregnancy rate, implantation rate and miscarriage rate. At this time, 71 deliveries have occurred with no reported abnormalities. There were 47 infants from 41 deliveries with day-5 blastocyst, 26 infants from 23 deliveries with day-6 blastocyst, and 8 infants from 7 deliveries with day-7 blastocyst. There were no differences among the three groups in the mean gestational age, preterm delivery rate and mean birth weight. These results indicated that blastocysts have similar inherent viability regardless of whether they develop by day 5, 6 or 7.

Vitrified human day-7 blastocyst transfer: 11 cases.

This case report describes successful pregnancies after vitrification of human day-7 blastocysts. A total of 16 day-7 blastocysts were vitrified and warmed. All 16 blastocysts survived after warming and were transferred to 11 patients. Six of the women (55%) became clinically pregnant and the implantation rate was 44% (7/16). Among these women, one woman delivered a healthy baby, two pregnancies ended in miscarriage, and three pregnancies are ongoing at 10, 29 and 34 weeks of gestation. This is the first report of successful pregnancies after vitrification of human day-7 blastocysts.

Case report: two successful pregnancies following the transfer of re-vitrified human day 7 blastocysts developed from vitrified cleaved embryos.

PURPOSE: To report successful pregnancies after the transfer of re-vitrified human day 7 blastocysts developed from vitrified cleaved embryos. METHODS AND RESULTS: A total of five day 7 blastocysts developed from vitrified cleaved embryos were re-vitrified and re-warmed. All of five re-vitrified day 7 blastocysts (100%) survived after warming and were transferred to three patients. Two of the women became clinically pregnant. Of these women, one woman delivered a healthy baby and the other pregnancy is ongoing at 26 weeks of gestation. CONCLUSIONS: This is the first report of successful pregnancies after the transfer of re-vitrified human day 7 blastocysts developed from vitrified cleaved embryos.

Effect of the size of zona pellucida opening by laser assisted hatching on clinical outcome of frozen cleaved embryos that were cultured to blastocyst after thawing in women with multiple implantation failures of embryo transfer: a retrospective study.

PURPOSE: To evaluate the effect of the size of zona pellucida opening by laser assisted hatching for frozen cleaved embryo that were thawed after both fresh and frozen cleaved embryo transfer cycles failed and were cultured to blastocyst after thawing in patients with multiple implantation failures. MATERIALS AND METHODS: Of 101 consecutive procedures (October 2003 to June 2006), 30 patients declined to perform assisted hatching and were selected as control group, 40 patients had 40 microm opening of the zona (October 2003 to January 2005), 31 patients had 50% of the zona opening (February 2005 to June 2006). RESULTS: The pregnancy, implantation and delivery rates were significantly higher in 50% opening group (74%, 52% and 65%) compared to control group (17%, 10% and 13%; P < 0.01) and 40 microm opening group (43%, 27% and 38%; P < 0.04). CONCLUSIONS: The size of the zona pellucida opening may affect the outcome of frozen cleaved embryo transfer.

Zona pellucida removal and vitrified blastocyst transfer outcome: a preliminary study.

The objective of this study was to investigate whether a change in assisted hatching technique from partial opening to total removal of the zona pellucida improved the outcome of vitrified blastocyst transfer. This was a preliminary observational study conducted from November 2003 to April 2006. Partial opening using acid Tyrode's solution was performed in 45 cycles, while total removal using a laser and mechanical pipetting was performed in 57 cycles. The clinical pregnancy, implantation, and delivery rates were higher in the total removal group than in the partial opening group (67% versus 42%, P < 0.02; 55% versus 30%, P < 0.01; 56% versus 36%, P < 0.04, respectively). These results suggest that total removal of the zona pellucida is associated with higher pregnancy, implantation and delivery rates compared with partial opening for vitrified blastocyst transfer.

Vitrification of human hatched blastocysts: a report of 4 cases.

BACKGROUND: Vitrification is a fairly well-established technique for cryopreservation of human zona-intact blastocysts. However, little is known about the efficacy of the vitrification technique for zona-free hatched blastocysts. CASE: A total of 4 hatched blastocysts from 4 healthy, infertile women undergoing in vitro fertilization were vitrified and warmed. All 4 hatched blastocysts expanded after warming and were transferred to 4 patients. Three of the women became clinically pregnant. Two healthy infants were born in 2 deliveries, and 1 pregnancy had progressed to 35 weeks at this writing. CONCLUSION: Our results suggest that vitrification is a useful cryopreservation technique not only for zona-intact blastocysts but also for zona-free hatched blastocysts.

Successful dizygotic twin pregnancy after recryopreservation by vitrification of human expanded blastocysts developed from frozen cleaved embryos on day 6: a case report.

BACKGROUND: Vitrification has evolved into an established technique for cryopreservation of human blastocysts. However, it is still unclear whether the blastocysts developed from frozen embryos can be cryopreserved a second time by vitrification for further embryo transfer. CASE: A 31-year-old woman underwent a long-treatment protocol for ovarian stimulation. Twenty-seven mature oocytes were obtained, and 21 were fertilized with intracytoplasmic sperm injection. On day 3, 2 cleaved embryos were transferred, but no implantation occurred. The remaining 19 embryos were cryopreserved with the slow freezing method. Three months after oocyte retrieval, 5 frozen day 3 embryos were thawed, the surviving 2 were transferred, but no implantation occurred. Six months after oocyte retrieval, the remaining 14 frozen day 3 embryos were thawed and the surviving 12 cultured. On day 5, 2 embryos reached the expanded blastocyst stage and were transferred, but no implantation occurred. On day 6, 5 of the nontransferred embryos became expanded blastocysts and were cryopreserved again by vitrification. Eight months after oocyte retrieval, 2 recryopreserved day 6 blastocysts were warmed and transferred. Implantation resulted in a dizygotic twin pregnancy. The pregnancy resulted in delivery of normal, healthy male and female infants weighing 2,155 and 2,590 g at birth, at 36 weeks of gestation. CONCLUSION: The blastocysts developed from frozen embryos on day 6 can be recryopreserved by vitrification and have pregnancy potential after warming.

Blastocoele collapse by micropipetting prior to vitrification gives excellent survival and pregnancy outcomes for human day 5 and 6 expanded blastocysts.

BACKGROUND: Manual puncture of the trophectoderm of human blastocysts with a needle before vitrification increases their survival rate, but the embryos take a long time to re-expand. This study examined whether causing human blastocysts to collapse by manual pipetting before vitrification would allow more rapid re-expansion and improve pregnancy rates. METHODS: After embryo transfer in IVF cycles, surplus embryos that developed to the expanded blastocyst stage were placed in cryoprotectant and then artificially shrunk by mechanical pipetting with a fine hand-drawn glass pipette slightly smaller in diameter than the blastocyst. The shrunken embryos were placed in a small volume of vitrification solution and plunged into liquid nitrogen on a cryotop. The blastocysts were thawed by warming and then dilution in 1 mol/l sucrose. RESULTS: Of 49 expanded vitrified blastocysts, 48 (98%) re-expanded within 3 h after warming. Following transfer (48 blastocysts in 28 cycles), 14 women (50%) became clinically pregnant, and the implantation rate was 33% (16/48). Eight healthy babies have been born in six deliveries, and the other eight pregnancies are ongoing. To date, there have been no spontaneous abortions. CONCLUSIONS: The results suggest that artificial shrinkage with pipetting is a simple and effective technique to assist successful cryopreservation of expanded blastocysts by vitrification.

Case report: successful pregnancy after vitrification of a human blastocyst that had completely escaped from the zona pellucida on day 6.

This case report describes a successful pregnancy after vitrification of a human hatched blastocyst. A 31-year-old woman, after failed stimulated and thaw cycles, underwent short-treatment protocol stimulation, and oocytes were recovered transvaginally with ultrasound guidance. Eight mature oocytes were obtained and six were fertilized with conventional IVF. Consecutive embryo transfer was performed, in which two cleaved embryos were transferred on day 3 and a single blastocyst was transferred on day 5, but no implantation occurred. On day 6, one of the non-transferred embryos developed into a blastocyst that had completely escaped from the zona pellucida. The zona-free hatched blastocyst was vitrified using a cryotop procedure after artificial shrinkage, which in our clinical experience has proved to be effective for zona-intact blastocysts. Six months after the previous retrieval cycle, the cryopreserved hatched blastocyst survived the warming process and was transferred to the patient's uterus. Implantation resulted in a healthy pregnancy; the pregnancy is ongoing at 33 weeks. This is the first report of a pregnancy after vitrification of a human blastocyst that had completely escaped from the zona pellucida.