To what degree should the zona pellucida be cut open in assisted hatching for best clinical results?

ObjectiveAssisted hatching is widely used to improve implantation by opening or thinning of Zona Pellucida artificially. However, there is no consensus to what degree the Zona Pellucida should be cut open for best clinical results. We compared the size of the opening of the Zona Pellucida with clinical results, using Saturn 5 ActiveTM (Research Instruments Ltd. UK) for lazar assisted hatching (LAH) and EmbryoScope○R(Vitrolife AB. Sweden) for continuous observation.Designprospective randmaized study.Materials and MethodsCryopreserved blastocysts (≧BB grade) which were donated by patients for research were used for this study. LAH was performed on warmed blastocysts after one hour of culturing. The blastocysts were divided into 5 groups by the size of the opening for assisted hatching: Group1 has been performed 50% opening (n=9) and Group2 has been performed 30% opening (n=12). Group3 has been conducted 12 micrometers opening (n=12) so as Group4 has been done the thinning (n=12). For Group5 no LAH has been performed (n=12).We observed the start timing of hatching, time of hatching, hatched rate and frequency of contraction until blastocysts finished hatching by Time Lapse after LAH.ResultsThe time until the initiating of hatching was significantly longer for groups 4 and 5 when compared to other groups. In fact, blastocysts of groups 4 and 5 needed 1-3 times of contraction to start hatching as found by Time Lapse observation. Time of hatching for Group 3 was significantly slower than for other groups. In that group, embryos were stuck by the small hole of the Zona Pellucida and repeated contraction occurred during hatching. The hatched rates were significantly lower in groups 3, 4 and 5 when compared to groups 1 and 2. Frequency of contraction until the blastocysts finished hatching was higher for groups 3, 4 and 5. There was no significant difference between groups 1 and 2.ConclusionsFrom this study, we found that adequate LAH improve subsequent hatching rates. In fact, the Zona Pellucida should not merely be thinned by rather cut open, at least 30%. ObjectiveAssisted hatching is widely used to improve implantation by opening or thinning of Zona Pellucida artificially. However, there is no consensus to what degree the Zona Pellucida should be cut open for best clinical results. We compared the size of the opening of the Zona Pellucida with clinical results, using Saturn 5 ActiveTM (Research Instruments Ltd. UK) for lazar assisted hatching (LAH) and EmbryoScope○R(Vitrolife AB. Sweden) for continuous observation. Assisted hatching is widely used to improve implantation by opening or thinning of Zona Pellucida artificially. However, there is no consensus to what degree the Zona Pellucida should be cut open for best clinical results. We compared the size of the opening of the Zona Pellucida with clinical results, using Saturn 5 ActiveTM (Research Instruments Ltd. UK) for lazar assisted hatching (LAH) and EmbryoScope○R(Vitrolife AB. Sweden) for continuous observation. Designprospective randmaized study. prospective randmaized study. Materials and MethodsCryopreserved blastocysts (≧BB grade) which were donated by patients for research were used for this study. LAH was performed on warmed blastocysts after one hour of culturing. The blastocysts were divided into 5 groups by the size of the opening for assisted hatching: Group1 has been performed 50% opening (n=9) and Group2 has been performed 30% opening (n=12). Group3 has been conducted 12 micrometers opening (n=12) so as Group4 has been done the thinning (n=12). For Group5 no LAH has been performed (n=12).We observed the start timing of hatching, time of hatching, hatched rate and frequency of contraction until blastocysts finished hatching by Time Lapse after LAH. Cryopreserved blastocysts (≧BB grade) which were donated by patients for research were used for this study. LAH was performed on warmed blastocysts after one hour of culturing. The blastocysts were divided into 5 groups by the size of the opening for assisted hatching: Group1 has been performed 50% opening (n=9) and Group2 has been performed 30% opening (n=12). Group3 has been conducted 12 micrometers opening (n=12) so as Group4 has been done the thinning (n=12). For Group5 no LAH has been performed (n=12).We observed the start timing of hatching, time of hatching, hatched rate and frequency of contraction until blastocysts finished hatching by Time Lapse after LAH. ResultsThe time until the initiating of hatching was significantly longer for groups 4 and 5 when compared to other groups. In fact, blastocysts of groups 4 and 5 needed 1-3 times of contraction to start hatching as found by Time Lapse observation. Time of hatching for Group 3 was significantly slower than for other groups. In that group, embryos were stuck by the small hole of the Zona Pellucida and repeated contraction occurred during hatching. The hatched rates were significantly lower in groups 3, 4 and 5 when compared to groups 1 and 2. Frequency of contraction until the blastocysts finished hatching was higher for groups 3, 4 and 5. There was no significant difference between groups 1 and 2. The time until the initiating of hatching was significantly longer for groups 4 and 5 when compared to other groups. In fact, blastocysts of groups 4 and 5 needed 1-3 times of contraction to start hatching as found by Time Lapse observation. Time of hatching for Group 3 was significantly slower than for other groups. In that group, embryos were stuck by the small hole of the Zona Pellucida and repeated contraction occurred during hatching. The hatched rates were significantly lower in groups 3, 4 and 5 when compared to groups 1 and 2. Frequency of contraction until the blastocysts finished hatching was higher for groups 3, 4 and 5. There was no significant difference between groups 1 and 2. ConclusionsFrom this study, we found that adequate LAH improve subsequent hatching rates. In fact, the Zona Pellucida should not merely be thinned by rather cut open, at least 30%. From this study, we found that adequate LAH improve subsequent hatching rates. In fact, the Zona Pellucida should not merely be thinned by rather cut open, at least 30%.