OBJECTIVE:To study whether the method of donor sperm cryopreservation, vitrification or slow freezing, affects embryological and clinical outcomes in in vitro fertilization (IVF) cycles. DESIGN:Retrospective cohort study. SUBJECTS:A total of 604 IVF cycles conducted between January 2023 and November 2024 using donor sperm cryopreserved by vitrification (n = 396) or slow freezing (n = 208). EXPOSURE:Cryopreservation method of donor sperm (vitrification vs. slow freezing). MAIN OUTCOME MEASURES:Fertilization rate, usable blastocyst rate, and clinical pregnancy rate after the first embryo transfer. RESULTS:Overall fertilization rates were similar between groups; however, stratified analysis by insemination technique revealed a significantly higher fertilization rate with vitrified sperm in conventional IVF cycles (76.4% vs. 65.9%; adjusted odds ratio [aOR] 1.95 [1.11-3.40]), whereas no difference was observed in intracytoplasmic sperm injection (ICSI) cycles (76.8% vs. 79.7%; aOR 0.84 [0.65-1.09]). Usable blastocyst and clinical pregnancy rates after the first embryo transfer were comparable between vitrification and slow freezing groups. Multivariable analyses adjusting for confounders confirmed these findings. CONCLUSION:Donor sperm vitrification is a safe alternative to conventional slow freezing and yields comparable blastocyst and clinical outcomes. Notably, in conventional IVF cycles, vitrification was associated with a significantly higher fertilization rate. This advantage was not observed in ICSI cycles, suggesting that vitrification better preserves sperm membrane functionality required for natural gamete interaction. Although clinical outcomes remain similar between both methods, reduced fertilization with slow-frozen sperm may decrease the number of embryos available, with potential implications for overall treatment efficiency.

Standard semen parameters remain the cornerstone of male infertility evaluation, though they often poorly reflect the likelihood of success in assisted reproductive technology (ART). This study evaluates sperm DNA fragmentation (SDF) as a diagnostic tool for male infertility and predictive biomarker for ART success. Semen samples were collected from 20 fertile donors and 40 infertile patients with abnormal semen parameters. A fraction of each sample was used for SDF assessment via TUNEL assay and flow cytometry, while the remaining portion was processed for conventional semen analysis and ART. Infertile patients exhibited higher SDF levels (32.77 ± 13.61%) compared to donors (22.19 ± 8.37%; p < 0.01), a difference that remained statistically significant across all subgroups stratified by semen parameters. Additionally, significant correlations were obtained between the percentage of SDF and sperm count (r = −0.4036), motility (r = −0.6377), and morphology (r = −0.2783). Regarding ART outcomes, patients with low-quality embryos exhibited higher SDF levels compared to those with high-quality embryos (30.02 ± 12.52% vs. 23.16 ± 8.41%; p = 0.0036). Receiver operating characteristic (ROC) curve analysis revealed an area under the curve (AUC) above 0.7 for the classification of male infertility as well as the assessment of embryo quality. Overall, our results support the utility of SDF as both a diagnostic biomarker for male infertility and a predictive indicator of embryo quality in ART, particularly in the presence of an oocyte-related female factor.

Study question What is the impact of discontinuing the reporting of low-grade mosaic embryos on PGT-A cycles’ outcomes? Summary answer Disregarding low grade mosaics leads to a significant increase in cycles with transferrable embryos without compromising clinical outcomes. What is known already In the context of PGT-A, uncertainty regarding the clinical relevance of chromosomal mosaicism has made it challenging for both professionals and patients to decide whether to transfer mosaic embryos. Consequently, many have been discarded. Yet, research has shown that such embryos can give rise to healthy babies. Lately, although there is still controversy, low-grade mosaics have been reported to be equivalent to euploid embryos in terms of clinical outcomes and risks. Thus, ESHRE guidelines on mosaicism opened the possibility of not reporting low-grade mosaicism. However, the impact of implementing such option in a PGT-A setting has not yet been assessed. Study design, size, duration Retrospective cohort study analysing 1718 PGT-A cycles performed from January 2021 to October 2024 at a university-affiliated fertility unit. Two groups were established based on low-grade mosaicism reporting policy: REPORTING (n = 1380) and NON-REPORTING (n = 338). Clinical pregnancy rates of transfers performed up to November 2024 were assessed for REPORTING group (n = 949) and NON-REPORTING group (n = 151). Additionally, PGT-A results of transferred embryos from NON-REPORTING group were revisited to detect low-grade mosaics and their outcomes were analysed. Participants/materials, setting, methods Trophectoderm biopsies from 5382 embryos were analysed by NGS. From January 2021 to January 2024, the REPORTING policy was applied: low-grade mosaics (30-50%) and high-grade mosaics (50-70%). From February 2024, NON-REPORTING policy was applied: euploid (<50%) and high-grade mosaics (50-70%). Primary outcomes measured were: mosaicism rate, % of cycles with mosaic embryos, % of cycles with only mosaic embryos for transfer, % cycles with no euploid embryos for transfer, and clinical pregnancy rates. Main results and the role of chance Both groups were similar in terms of female and male age, female BMI, number of pick-ups per PGT-A cycle, total dose of gonadotropins, days of ovarian stimulation, number of oocytes retrieved, number of MII oocytes, and number of biopsied blastocysts. As expected, mosaicism rate was inferior in NON-REPORTING group (3.9% [95%CI (%): 2.5-5.2]) compared to REPORTING group (6.8% [95%CI (%): 6.0-7.5]), while euploidy rate was higher (41.1% [95%CI (%): 37.6-44.6] vs 35.9% [95%CI (%): 34.2-37.5]). No differences were observed in aneuploidy rates (47.5% vs 52.4%, NS). The percentage of cycles with at least one mosaic embryo was lower in NON-REPORTING group 9.8% (33/338) compared to REPORTING group 18.5% (255/1380) (p < 0.001). Most interestingly, the percentage of cycles with no euploid embryos for transfer was significantly reduced in the NON-REPORTING group (34.3% vs 41.5%, p = 0.009). The adoption of the NON-REPORTING policy did not negatively impact on clinical pregnancy: 53.6% (81/151) vs 57.4% (545/949) in REPORTING group (p = 0.2). A total of 22 transferred embryos from NON-REPORTING group, that would have been classified as low-grade mosaics according to the REPORTING policy, presented the following clinical outcomes: biochemical pregnancy 54.5% (12/22), clinical pregnancy 45.4% (10/22), miscarriage 10.0% (1/10), and ongoing pregnancy 40.9% (9/22). All ongoing pregnancies are normally developing. Limitations, reasons for caution Retrospective study. Data on clinical outcomes for the NON-REPORTING group is preliminary and should be further confirmed with extended pregnancy follow-up and increased sample size.. NON-REPORTING policy of low-grade mosaicism should not be adopted without providing patients with an adequate pre-test consultation with full disclosure of the chosen policy. Wider implications of the findings Results suggest that disregarding low-grade mosaicism avoids unnecessary uncertainty to patients without compromising clinical outcomes. As a result, an increase in cumulative live birth could be expected. Given all, it may be the time to consider of no value the reporting of a low-grade mosaicism. Trial registration number No

Research question: Is partial compaction during morula formation associated with an embryo's developmental ability and Design: Retrospective analysis of data from 196 preimplantation genetic testing for aneuploidy (PGT-A) cycles. Embryos starting compaction were grouped according to the inclusion or not of all the blastomeres in the forming morula (full compaction or partial compaction). The possible effect of maternal age and ovarian response on compaction was analysed. Morphokinetic characteristics, blastocyst formation rate, morphology and cytogenetic constitution of the obtained blastocysts were compared. Comparisons of reproductive outcomes after the transfer of euploid blastocysts from both groups were established. Finally, in a subset of embryos, the chromosomal constitution concordance of the abandoned cells and the corresponding blastocyst through trophectoderm biopsies was assessed. Results: A total of 430 embryos failed to include at least one cell during compaction (partial compaction group [49.3%]), whereas the 442 remaining embryos formed a fully compacted morula (full compaction group [50.7%]). Neither female age nor the number of oocytes collected affected the prevalence of partial compaction morulae. Morphokinetic parameters were altered in embryos from partial compaction morulae compared with full compaction. Although an impairment in blastocyst formation rate was observed in partial compaction morulae (57.2% versus 70.8%, P < 0.001), both chromosomal constitution (euploidy rate: partial compaction [38.4%] versus full compaction [34.2%]) and reproductive outcomes (live birth rate: partial compaction [51.9%] versus full compaction [46.2%]) of the obtained blastocysts were equivalent between groups. A high ploidy Conclusions: Partial compaction morulae show a reduced developmental ability compared with full compaction morulae. be a consequence of a compromised embryo development regardless of the chromosomal constitution of the excluded cells.

Little is known about the effects of low gravity on human gametes. The aim of this study was to analyze if fresh human sperm samples after fast gravity load changes suffered any detrimental effect in comparison to the splits maintained in Earth’s gravity. Fifteen fresh samples from normozoospermic donors were analyzed. Statistically significant differences in vitality (69.7 ± 9.9 % vs 72.4 ± 9.7 %, [95% CI: 0.002,0.07]); motile sperm concentration (23.7 ± 15.3 M/ml vs 31.5 ± 25.1 M/ml, [95% CI: 1.03,14.65]); grade “a” sperm concentration (8.7 ± 6.5 M/ml vs 11.7 ± 9.9 M/ml, [95% CI: 0.71,5.28]); percentage of progressive motility sperm (30 ± 12.9 % vs 36 ± 14.3 %, [95% CI: 0.10,0.37]) and curvilinear velocity VCL: 45.7 ± 12.8 μm/s vs 47.7 ± 13.3 μm/s, [95% CI: 0.79,3.22]) were observed. No statistical differences were observed in other sperm kinematic parameters, morphology, DNA fragmentation, apoptosis, and oxidative stress. In conclusion, even though it did not result in a total loss, heavy gravity load changes including microgravity causes a significant decrease in sperm vitality and motility suggesting that negative consequences would be even higher if the exposure were longer. The results obtained indicate that further research is really needed before Assisted Reproduction will be considered for the future human reproduction outside the Earth.

To determine whether embryo mosaicism prevalence in preimplantation genetic testing for aneuploidy (PGT-A) cycles is associated with the trophectoderm biopsy technique used (a. number of laser pulses or b. the use of flicking or pulling) or the time to tubing. Prospective observational study performed in a single IVF-PGT-A setting from May 2019 to May 2021. Trophectoderm biopsies were analysed by next-generation sequencing. Mosaicism was analysed in relation to the biopsy methodology (number of laser pulses and pulling vs flicking), time elapsed from biopsy to tubing (min), and time of sample cryostorage from tubing to amplification (days). As a secondary objective, the number of laser pulses and biopsy methodology were studied in relation to clinical outcomes of transferred euploid blastocysts. None of the analysed variables were associated to mosaicism prevalence. Multivariable regression analysis demonstrated that mosaicism prevalence was comparable either when  > 3 laser pulses were used as compared to ≤ 3 (13.9% vs 13.8%, aOR = 0.8726 [0.60–1.28]) and pulling compared to flicking (13.1% vs 14.0%, aOR = 0.86 [0.60–1.23]). Moreover, neither the number of laser pulses during biopsy (> 3 vs ≤ 3) nor the technique used (pulling vs flicking) were associated with clinical pregnancy after the transfer of frozen-thawed euploid blastocysts (54.9% vs 55.2%, aOR = 1.05 [0.53–2.09]; 61.1% vs 52.9%, aOR = 1.11 [0.55–2.25], respectively). Our results suggest that, as long as the biopsy and tubing procedures are performed following standardized high quality procedures, no specific approach would increase the generation of artefactual mosaicism as a result of trophectoderm biopsy. Trophectoderm biopsies should be performed regardless of the methodology but always aiming on minimising blastocyst manipulation.

ObjectiveTo assess patients' and embryonic characteristics that may have an influence on the decision to transfer a mosaic embryo. MethodSingle centre retrospective cohort study including 1247 PGT-A cycles. Demographic and clinical factors associated with a decision to transfer a mosaic embryo were studied. Female age, number of previous cycles, previous availability of euploid embryos, history of miscarriages and parity as well as percentage of mosaicism, type of anomaly and chromosome risk were studied in relation to decision-making. Outcomes after mosaic embryo transfer were assessed. ResultsTo date, in 7.9% of cycles (99/1247), patients have had to make a decision on the fate of their mosaic embryos. In 23.2% of cycles (23/99), patients decided to transfer. In most cases (79.8%; 79/99), patients underwent genetic counselling before the decision. None of the variables analysed were associated with the patients' decision, although parity and the high-degree mosaicism (>50%) seemed to be negatively associated with the decision to transfer (18.2% vs. 29.8%, p = 0.294; 10% vs. 32.2%, p = 0.052). ConclusionsNeither reproductive history nor information on mosaic embryo characteristics through counselling seems to be determinative for patients when deciding to transfer a mosaic embryo. Promising and increasing data on clinical outcomes after mosaic embryo transfer will be of utmost importance to soften risk perception regarding mosaic embryos and give a better, simplified and more evidence-based counselling.

Research question: Are intrinsic or extrinsic factors associated with embryo mosaicism prevalence in IVF cycles? Design: Retrospective cohort study of preimplantation genetic testing for aneuploidy (PGT-A) cycles carried out at a university-affiliated IVF clinic between October 2017 and October 2019. Trophectoderm biopsies were analysed by next generation sequencing. Mosaicism prevalence, type of anomaly and the chromosomes involved were analysed. Intrinsic and extrinsic factors potentially inducing mosaicism were studied: maternal and paternal age, antral follicle count, cumulus-oocyte complexes retrieved, female body mass index, PGT-A indication, sperm concentration, total dosage of gonadotrophins, embryo quality and day of blastocyst formation, single-step commercial media used and biopsy operator. Results: Overall prevalence of mosaicism in our PGT-A setting was 13.9%. In segmental mosaicism, larger chromosomes tended to be more affected, which was not observed in whole-chromosome mosaicism. Additionally, segmental mosaicism was mostly observed in monosomy (69.6%; P < 0.01) compared with whole-chromosome mosaicism (49.7% monosomies versus 50.3% trisomies; P = 0.83). Although a high inter-patient variability was observed, only paternal age showed a positive association with mosaicism (adjusted OR 1.26, 95% CI 1.02 to 1.54) among the analysed variables. Conclusions: Our results suggest remarkable differences in the mechanisms generating segmental and whole-chromosome mosaicism, indicating that they may deserve different consideration when studying them and when prioritizing them for transfer. Male factor seems to be associated with mosaicism and may be worthy of specific assessment in future studies.

Conservative and functional surgery is increasingly used in surgical oncology. Its aim is to preserve organs’ functionality and to reduce radical resection. Development of new surgical procedures in oncologic gynecologic surgery is a perfect example of this evolution. Although radical surgery remains the gold standard in the treatment of ovarian cancer, a conservative approach can be considered in patients with early-stages disease, in order to preserve their fertility function. These procedures were proposed to selected patients, depending on histologic subtypes and prognostic factors. Ovarian cancers are classified in epithelial (including borderline and malignant tumors) and non-epithelial cancer.

Summary The aim of this study was to provide a more comprehensive understanding of 1PN intracytoplasmic sperm injection (ICSI) zygotes. To achieve this objective, we assessed whether all 1PN-derived embryos showed a similar morphokinetic pattern, and if the morphokinetic behaviour of 1PN-derived embryos was comparable with that of 2PN-derived embryos. In total, 149 1PN ICSI zygotes (study group) and 195 2PN ICSI zygotes (control group) were included in the study. Embryo development potential was evaluated in terms of blastocyst rate. Morphokinetic parameters, including the pronucleus diameter and kinetics of in vitro development, were also analyzed. Embryos derived from 1PN ICSI zygotes showed impaired development compared with 2PN-derived embryos, with blastocyst rates of 28.9% and 67.2%, respectively. The diameter of the pronucleus of 1PN zygotes was larger than that of 2PN zygotes. When compared with 2PN-derived embryos, those derived from 1PN zygotes had a visible pronucleus for a shorter time, in addition to a longer syngamy time and slower kinetic behaviour from two to nine cells. When 1PN-derived blastocysts and 2PN-derived blastocysts were compared, the developmental kinetics were similar in both groups, except for a delayed and longer duration of the compaction phase in 1PN-derived embryos. In conclusion, monopronucleated ICSI zygotes present differences in developmental capacity and morphokinetic behaviour compared with 2PN ICSI zygotes, showing particular morphokinetic parameters related to pronucleus formation. Only the 1PN ICSI-derived embryos that reached the blastocyst stage have similar morphokinetic development to blastocysts from 2PN zygotes.

To determine the developmental competence of fast-cleaving D3 embryos. Retrospective study including 4028 embryos from 513 PGT-A cycles performed between July 2014 and June 2017. Embryos were cultured in time-lapse incubators and biopsied at blastocyst stage. Embryos were classified in groups according to the number of cells on D3 (from 2-cell to ≥13 -cell and compacted). A generalized linear mixed model adjusted for confounding factors was performed to assess the chance to give rise to an euploid blastocyst in each group compared with the chance of 8-cell embryos. Implantation and live birth rates were also analyzed. The statistical analysis showed that embryos with 9 to 11 cells had a slightly lower euploid blastocyst rate than 8-cell embryos (OR (95% CI) 0.77 (0.61–0.96)) while embryos with more than 11 cells were found to be just as likely to give rise to an euploid blastocyst as the 8-cell embryos (OR (95% CI) 1.20 (0.92–1.56)). Conversely, slow-cleaving embryos had a significantly lower euploid blastocyst rate than 8-cell embryos (OR (95% CI) 0.31 (0.24–0.39)). Moreover, euploid blastocysts derived from fast-cleaving embryos and from 8-cell embryos exhibit similar live birth rates. No significant differences were found in the chance to give rise a live birth between 8-cell and 9- to 11-cell embryos (OR (95% CI) 1.23 (0.70–2.15)) and > 11-cell embryos (OR (95% CI) 1.09 (0.57–2.09)). Embryos with more than 11 cells exhibit similar developmental competence to 8-cell embryos. Their poor prognosis should be reconsidered.

The transition in biopsy timing from blastomere to trophectoderm biopsy has led to a remarkable decrease in the percentage of undiagnosed blastocysts. However, patients with few or no euploid blastocysts can be affected by this residual percentage of diagnosis failure. The aim of this study is to assess whether blastocyst rebiopsy and revitrification is an efficient and safe procedure to be applied in cases of no results after analysis. Fifty-three patients agreed to the warming of 61 blastocysts to perform a second biopsy and PGT-A by aCGH. Only 75.4% of the blastocysts survived, reexpanded, and could be rebiopsied. After the second biopsy and analysis, 95.6% of the blastocysts were successfully diagnosed with an euploidy rate of 65.9%. Eighteen euploid blastocysts were warmed and transferred to 18 patients with a 100% survival and reexpansion rate. Seven clinical pregnancies have been achieved with 4 live births, 1 ongoing pregnancy, and 2 miscarriages. Thus, although few transfers of rebiopsied and revitrified blastocysts have been performed till date, our preliminary results show that this approach is efficient and safe to be applied for undiagnosed blastocysts, as it ultimately allows the transfer of euploid blastocysts and good clinical outcomes.

Summary Shortly after the implementation of comprehensive chromosome screening (CCS) techniques for preimplantation genetic testing for aneuploidies (PGT-A), the discussion about the transition from day 3 to blastocyst stage biopsy was initiated. Trophectoderm biopsy with CCS is meant to overcome the limitations of cleavage-stage biopsy and single-cell analysis. The aim of this study was to assess the results obtained in our PGT-A programme after the implementation of this new strategy. Comparisons between the results obtained in 179 PGT-A cycles with day 3 biopsy (D+3) and fresh embryo transfer, and 204 cycles with trophectoderm biopsy and deferred (frozen–thawed) embryo transfer were established. Fewer embryos were biopsied and a higher euploidy rate was observed in the trophectoderm biopsy group. No differences in implantation (50.3% vs. 61.4%) and clinical pregnancy rate per transfer (56.1% vs. 65.3%) were found. Although the mean number of euploid embryos per cycle did not differ between groups (1.5 ± 1.7 vs. 1.7 ± 1.8), the final number of euploid blastocysts available for transfer per cycle was significantly higher in the trophectoderm biopsy group (1.1 ± 1.3 vs. 1.7 ± 1.8). This factor led to an increased cumulative live birth rate in this last group (34.1% vs. 44.6%). Although both strategies can offer good results, trophectoderm biopsy offers a more robust diagnosis and the intervention is less harmful for the embryos so more euploid blastocysts are finally available for transfer and/or vitrification.

El presente estudio describe la implementación de un test de cribado de portadores de enfermedades genéticas autosómicas recesivas y enfermedades ligadas al cromosoma X en un programa de donación de ovocitos (donantes de ovocitos y parejas masculinas de las receptoras). El test empleado basado en tecnología Next-Generation Sequencing (NGS), cubría 200 genes (68 mediante análisis completo de secuencia codificante y 132 por estrategia dirigida de análisis) asociados a 314 enfermedades (277 enfermedades autosómicas recesivas y 22 ligadas al cromosoma X). El resultado obtenido tras 2,5 años mostró un alto grado de aceptación (implementación>80%). Se identificaron un 56,4% de individuos (761/1.350) portadores de al menos una mutación patogénica. Asimismo se identificó que el 1,9% de las candidatas a donantes eran portadoras de una enfermedad ligada al cromosoma X por lo que se excluyeron del programa de Donación de Ovocitos. La carga mutacional media fue de 0,84 mutaciones por muestra. Se identificaron un 3,4% de preasignaciones donante-receptor con alto riesgo reproductivo para alguna enfermedad genética recesiva (fibrosis quística, hiperplasia suprarrenal congénita, sordera congénita no-sindrómica, alfa-talasemia, fiebre mediterránea familiar, enfermedad de Niemann-Pick, dishormonogénesis tiroidea tipo 6 e hipoplasia de cartílago-pelo). La asignación definitiva se realizó teniendo en cuenta los resultados de los estudios genéticos. El estado de portador heterocigoto para una enfermedad autosómica recesiva no fue motivo de exclusión del programa de Donación de Ovocitos, pero implicó la selección de una receptora cuya pareja masculina no fuera portadora de la misma enfermedad. El asesoramiento genético de donantes y receptores en las diferentes etapas del proceso clínico de la donación de ovocitos fue esencial para disminuir la ansiedad, conseguir una buena comprensión de los resultados y poder otorgar las recomendaciones pertinentes sobre el riesgo reproductivo propio o de sus familiares, cuando fue necesario.

An external quality-control programme for morphology-based embryo quality assessment, incorporating a standardized embryo grading scheme, was evaluated over a period of 5 years to determine levels of inter-observer reliability and agreement between practising clinical embryologists at IVF centres and the opinions of a panel of experts. Following Guidelines for Reporting Reliability and Agreement Studies, the Gwet index and proportion of positive (Ppos) and negative agreement were calculated. For embryo morphology assessment, a substantial degree of reliability was measured between the centres and the panel of experts (Gwet index: 0.76; 95% CI 0.70 to 0.84). The agreement was higher for good- versus poor-quality embryos. When multinucleation or vacuoles were observed, low levels of reliability were obtained (Ppos: 0.56 and 0.43, respectively). In blastocysts, the characteristic that presented the largest discrepancy was that related to the inner cell mass. In decisions about the final disposition of the embryo, reliability between centre and the panel of experts was moderate (Gwet index: 0.51; 95% CI 0.41 to 0.60). In conclusion, the ability of clinical embryologists to evaluate the presence of multinucleation and vacuoles in the early cleavage embryo, and to determine the category of the inner cell mass in blastocysts, needs to be improved.

OBJECTIVE:This study aims to increase the knowledge about monopronucleated ICSI-derived blastocysts, analyzing trophectoderm biopsies by aCGH and FISH to evaluate their chromosome constitution.METHODS:Fifteen monopronucleated ICSI-derived blastocysts were studied. Double trophectoderm biopsy was performed and analyzed by FISH and aCGH. The blastocysts were classified according to chromosome constitution. Disagreements between the two techniques were assessed.RESULTS:Results obtained after FISH and aCGH analyses showed the following: 20% (3/15) and 60% (9/15) diploid females, respectively; 26.7% (4/15) and 26.7% (4/15) diploid males, respectively; and 53.3% (8/15) and 13.3% (2/15) mosaics, respectively. No mosaic male embryos were found using FISH or aCGH. There were disagreements in 40% (6/15) of the cases due to the higher detection of mosaicism by FISH compared to aCGH.CONCLUSIONS:The combination of FISH and aCGH has been shown to be a suitable approach to increase the knowledge about monopronucleated ICSI-derived embryos. FISH analysis of blastocysts derived from monopronucleated ICSI zygotes enabled us to conclude that aCGH underestimates haploidy. Some diploid embryos diagnosed by aCGH are in fact mosaic. In cases where these embryos would be used for reproductive purposes, extra analysis of parental genome origin is recommended.

Purpose The objective of this work was to determine which embryonic morphokinetic parameters up to D3 of in vitro development have predictive value for implantation for the selection of embryos for transfer in clinical practice based upon information generated from embryo transfers with known implantation data (KID).Methods A total of 800 KID embryos (100% implantation rate (IR) per transfer and 0% IR per transfer) cultured in an incubator with Time-Lapse system were retrospectively analysed. Of them, 140 embryos implanted, whereas 660 did not.Results The analysis of morphokinetic parameters, together with the embryo morphology assessment on D3, enabled us to develop a hierarchical model that places the classical morphological score, the t4 and t8 morphokinetic values, as the variables with the best prognosis of implantation.Conclusion In our decision tree, the classical morphological score is the most predictive parameter. Among embryos with better morphological scores, morphokinetics permits deselection of embryos with the lowest implantation potential.

La multinucleación es un fenómeno frecuente en los embriones obtenidos por fecundación in vitro y suele asociarse a un pobre pronóstico reproductivo. La monitorización embrionaria en sistemas de cultivo time-lapse permite la observación detallada y continua del desarrollo embrionario. En nuestro trabajo se ha evaluado el impacto de la presencia de multinucleación en la morfocinética, la capacidad de desarrollo y la implantación embrionaria. Estudio retrospectivo de cohorte. Se han incluido 5.540 embriones cultivados en TL (Embryoscope®, Unisense Fertilitech®) procedentes de 763 ciclos de FIV-ICSI realizados durante el periodo 2012-2014. La presencia de multinucleación se evaluó en todas las etapas del desarrollo. La transferencia embrionaria se realizó en D + 3, y los embriones multinucleados se cultivaron hasta alcanzar el estadio de blastocisto. Un 23,6% de los embriones mostraron multinucleación en algún momento del desarrollo embrionario. Los valores de los parámetros morfocinéticos de los embriones multinucleados y no multinucleados mostraron diferencias estadísticamente significativas. El 18% de los embriones multinucleados alcanzaron el estadio de blastocisto y fueron congelados. No se observó efecto ni del tipo de multinucleación ni del porcentaje de células multinucleadas sobre la tasa de blastocisto. La tasa de implantación de los blastocistos procedentes de embriones multinucleados fue del 39,1%. La monitorización embrionaria continua permite una mejor detección de la multinucleación. La presencia de multinucleación embrionaria se asocia a una morfocinética alterada y una capacidad de desarrollo reducida. No obstante, los embriones multinucleados que alcanzan el estadio de blastocisto muestran una elevada capacidad de implantación. Multinucleation is a common phenomenon in in vitro human embryos and is associated with a poor outcome. Time-lapse monitoring of embryo development allows a continuous and detailed observation of fertilisation and cleavage events. An evaluation is presented on the impact of the presence of multinucleation on embryo morphokinetics, developmental ability, and implantation potential. A retrospective cohort study was conducted on a total of 5540 embryos cultured in a TL system (Embryoscope®, Unisense Fertilitech®) from 763 ICSI cycles performed between 2012 and 2014. Presence of multinucleation in all developmental stages was assessed. Embryo replacement was performed on D + 3. Multinucleated embryos were cultured to the blastocyst stage and cryopreserved for subsequent transfer. Approximately one quarter (23.6%) of the studied embryos showed multinucleation. Multinucleated embryos showed altered morphokinetic parameters compared to the non-multinucleated ones. The multinucleated embryos that reached the blastocyst stage (18%) were cryopreserved. No differences in the developmental ability were observed compared to the multinucleated type or percentage of multinucleated cells. There was a 39.1% implantation rate of the blastocysts obtained from multinucleated embryos. Time-lapse monitoring of embryo development allows a better detection of the multinucleation phenomenon. The presence of multinucleated cells is associated with changes in the morphokinetics and a reduced developmental ability. However, multinucleated embryos that reach the blastocyst stage can be replaced, and have a high implantation potential.

Next-generation sequencing (NGS) has the capacity of carrier screening in gamete donation (GD) programs. We have developed and validated an NGS carrier-screening test (qCarrier test) that includes 200 genes associated with 368 disorders (277 autosomal recessive and 37 X-linked). Carrier screening is performed on oocyte donation candidates and the male partner of oocyte recipient. Carriers of X-linked conditions are excluded from the GD program, whereas donors are chosen who do not carry mutations for the same gene/disease as the recipients. The validation phase showed a high sensitivity (>99% sensitivity) detecting all single-nucleotide variants, 13 indels, and 25 copy-number variants included in the validation set. A total of 1,301 individuals were analysed with the qCarrier test, including 483 candidate oocyte donors and 635 receptor couples, 105 females receiving sperm donation, and 39 couples seeking pregnancy. We identified 56% of individuals who are carriers for at least one genetic condition and 1.7% of female donors who were excluded from the program due to a carrier state of X-linked conditions. Globally, 3% of a priori assigned donations had a high reproductive risk that could be minimized after testing. Genetic counselling at different stages is essential for helping to facilitate a successful and healthy pregnancy.

OBJECTIVE:To assess whether preimplantation genetic screening can successfully identify cytogenetically normal embryos in couples carrying balanced chromosome rearrangements in addition to increased sperm DNA fragmentation. DESIGN:Comprehensive preimplantation genetic screening was performed on three couples carrying chromosome rearrangements. Sperm DNA fragmentation was assessed for each patient. SETTING:Academic center. PATIENT(S):One couple with the male partner carrying a chromosome 2 pericentric inversion and two couples with the male partners carrying a Robertsonian translocation (13:14 and 14:21, respectively). INTERVENTION(S):A single blastomere from each of the 18 cleavage-stage embryos obtained was analysed by metaphase comparative genomic hybridization. Single- and double-strand sperm DNA fragmentation was determined by the alkaline and neutral Comet assays. MAIN OUTCOME MEASURE(S):Single- and double-strand sperm DNA fragmentation values and incidence of chromosome imbalances in the blastomeres were analyzed. RESULT(S):The obtained values of single-strand sperm DNA fragmentation were between 47% and 59%, and the double-strand sperm DNA fragmentation values were between 43% and 54%. No euploid embryos were observed in the couple showing the highest single-strand sperm DNA fragmentation. However, euploid embryos were observed in the other two couples: embryo transfer was performed, and pregnancy was achieved by the couple showing the lowest sperm DNA fragmentation values. CONCLUSION(S):Preimplantation genetic screening enables the detection of euploid embryos in couples affected by balanced chromosome rearrangements and increased sperm DNA fragmentation. Even though sperm DNA fragmentation may potentially have clinical consequences on fertility, comprehensive preimplantation genetic screening allows for the identification and transfer of euploid embryos.