Cleavage-stage versus blastocyst-stage embryo transfer in assisted reproductive technology.

BACKGROUND: Advances in embryo culture media have led to a shift in in vitro fertilisation (IVF) practice from cleavage-stage embryo transfer to blastocyst-stage embryo transfer. The rationale for blastocyst-stage transfer is to improve both uterine and embryonic synchronicity and enable self selection of viable embryos, thus resulting in better live birth rates. OBJECTIVES: To determine whether blastocyst-stage (day 5 to 6) embryo transfer improves the live birth rate (LBR) per fresh transfer, and other associated outcomes, compared with cleavage-stage (day 2 to 3) embryo transfer. SEARCH METHODS: We searched the Cochrane Gynaecology and Fertility Group Specialised Register of controlled trials, CENTRAL, MEDLINE, Embase, PsycINFO, and CINAHL, from inception to October 2021. We also searched registers of ongoing trials and the reference lists of studies retrieved. SELECTION CRITERIA: We included randomised controlled trials (RCTs) which compared the effectiveness of IVF with blastocyst-stage embryo transfer versus IVF with cleavage-stage embryo transfer. DATA COLLECTION AND ANALYSIS: We used standard methodological procedures recommended by Cochrane. Our primary outcomes were LBR per fresh transfer and cumulative clinical pregnancy rates (cCPR). Secondary outcomes were clinical pregnancy rate (CPR), multiple pregnancy, high-order multiple pregnancy, miscarriage (all following first embryo transfer), failure to transfer embryos, and whether supernumerary embryos were frozen for transfer at a later date (frozen-thawed embryo transfer). We assessed the overall quality of the evidence for the main comparisons using GRADE methods. MAIN RESULTS: We included 32 RCTs (5821 couples or women). The live birth rate following fresh transfer was higher in the blastocyst-stage transfer group (odds ratio (OR) 1.27, 95% confidence interval (CI) 1.06 to 1.51; I2 = 53%; 15 studies, 2219 women; low-quality evidence). This suggests that if 31% of women achieve live birth after fresh cleavage-stage transfer, between 32% and 41% would do so after fresh blastocyst-stage transfer. We are uncertain whether blastocyst-stage transfer improves the cCPR. A post hoc analysis showed that vitrification could increase the cCPR. This is an interesting finding that warrants further investigation when more studies using vitrification are published. The CPR was also higher in the blastocyst-stage transfer group, following fresh transfer (OR 1.25, 95% CI 1.12 to 1.39; I2 = 51%; 32 studies, 5821 women; moderate-quality evidence). This suggests that if 39% of women achieve a clinical pregnancy after fresh cleavage-stage transfer, between 42% and 47% will probably do so after fresh blastocyst-stage transfer. We are uncertain whether blastocyst-stage transfer increases multiple pregnancy (OR 1.05, 95% CI 0.83 to 1.33; I2 = 30%; 19 studies, 3019 women; low-quality evidence) or miscarriage rates (OR 1.12, 95% CI 0.90 to 1.38; I2 = 24%; 22 studies, 4208 women; low-quality evidence). This suggests that if 9% of women have a multiple pregnancy after fresh cleavage-stage transfer, between 8% and 12% would do so after fresh blastocyst-stage transfer. However, a sensitivity analysis restricted only to studies with low or 'some concerns' for risk of bias, in the subgroup of equal number of embryos transferred, showed that blastocyst transfer probably increases the multiple pregnancy rate. Embryo freezing rates (when there are frozen supernumerary embryos for transfer at a later date) were lower in the blastocyst-stage transfer group (OR 0.48, 95% CI 0.40 to 0.57; I2 = 84%; 14 studies, 2292 women; low-quality evidence). This suggests that if 60% of women have embryos frozen after cleavage-stage transfer, between 37% and 46% would do so after blastocyst-stage transfer. Failure to transfer any embryos was higher in the blastocyst transfer group (OR 2.50, 95% CI 1.76 to 3.55; I2 = 36%; 17 studies, 2577 women; moderate-quality evidence). This suggests that if 1% of women have no embryos transferred in planned fresh cleavage-stage transfer, between 2% and 4% probably have no embryos transferred in planned fresh blastocyst-stage transfer. The evidence was of low quality for most outcomes. The main limitations were serious imprecision and serious risk of bias, associated with failure to describe acceptable methods of randomisation. AUTHORS' CONCLUSIONS: There is low-quality evidence for live birth and moderate-quality evidence for clinical pregnancy that fresh blastocyst-stage transfer is associated with higher rates of both than fresh cleavage-stage transfer. We are uncertain whether blastocyst-stage transfer improves the cCPR derived from fresh and frozen-thawed cycles following a single oocyte retrieval. Although there is a benefit favouring blastocyst-stage transfer in fresh cycles, more evidence is needed to know whether the stage of transfer impacts on cumulative live birth and pregnancy rates. Future RCTs should report rates of live birth, cumulative live birth, and miscarriage. They should also evaluate women with a poor prognosis to enable those undergoing assisted reproductive technology (ART) and service providers to make well-informed decisions on the best treatment option available.

COVID-19 risk assessment and safety management operational guidelines for IVF center reopening.

PURPOSE: To promote nationwide dissemination and implementation of COVID-19 Risk Assessment and Safety Management Operational Guidelines, drawn up by SAMeR Task Force in ART centers in Argentina. Our objective is to prevent and mitigate the transmission of SARS-CoV-2 at an institutional level, while reducing the risk of infection among both physicians and patients in the context of a critical scenario in the local and Latin American healthcare system. METHODS: SAMeR Executive Committee set up a crisis committee which was made up of specialists in reproductive medicine, embryology, and healthcare management. A critical and updated review of the advances in science, documents, and recommendations released by other societies (ASRM, ESHRE, IFFS, Red LARA, societies of anesthesiologists, infectious diseases, and Occupational Safety and Health Administration-OSHA) was carried out. Likewise, there were joint meetings with the Ministry of Health of Argentina in order to draw up the guidelines. Simultaneously, ongoing medical training was carried out, thus providing added value to them, including two status surveys of the activities of the monovalent and polyvalent centers according to the country's epidemiological mapping. Four additional recommendations were made, and online training was given to healthcare workers. The aforementioned regulations were first analyzed by the healthcare providers and their practical suggestions were then added to the guidelines. RESULTS: The one-off collaborative work and the actions coordinated with the National ART Program of the Ministry of Health of Argentina resulted in the development and implementation of the present COVID-19 Risk Assessment and Safety Management Operational Guidelines at a national level. SAMeR gave recommendations for the implementation of the Management Guidelines for the center reopening, providing new safety criteria against the threat of viral contagion. A new organizational culture was promoted through the awareness of all the healthcare workers and teaching responsibility. We continue working on the compliance with a new "Code of Conduct and Commitment in Healthcare" and with workplace safety measures. We helped with transforming the theoretical knowledge into practical measures for the healthcare workers in different services, with the aim to prevent, mitigate, and/or handle contingencies at the centers/services and gamete banks, in line with the actions agreed upon with the Ministry of Health. CONCLUSIONS: As an extraordinary and uncertain event, the SARS-CoV-2 pandemic helped consolidate a volunteer-based and collaborative panel of SAMeR experts who developed the COVID-19 Risk Assessment and Safety Management Operational Guidelines as a new and readily available tool for physicians, patients, and gamete banks care. Their implementation has provided specific guidelines to minimize risk for professionals in ART clinics, as well as guaranteeing patient safety.

Effect of sperm DNA fragmentation on embryo development: clinical and biological aspects.

OBJECTIVE: The aim of this study was to investigate the effect of sperm DNA fragmentation on fertilization rate, embryo development (blastulation rate), and pregnancy outcomes for ICSI cycles performed in a cohort of couples using donor eggs and to assess the remaining embryos that were not transferred or frozen for apoptotic markers. METHODS: Eighty-two women (egg recipients) were included in the study (2016) were included in the study. The recipients' mean age was 41.8±5.1 y/o (36-49), while the egg donors' mean age was 30.8±2.1 y/o (27-33). Even though donor egg cycles with frozen sperm samples are performed regularly in our center, 35 cycles were done using fresh sperm samples. The mean age of the males involved in the procedure was 40.1±5.2 y/o. Fertilization, blastulation, and pregnancy rates were assessed. The patients were divided into two groups, TUNEL <15% and ≥15%. In arrested embryos, ICC was performed to detect cleaved caspase-3, survivin, TUNEL, and DNA. The Student's t-test was used in between-group comparisons. The Mann-Whitney U-test was used to assess homogeneity. Pearson's correlation coefficient was also calculated. p<0.05 was considered statistically significant. RESULTS: This study showed that there is a negative correlation (R=-0.5) between DNA fragmentation and blastulation rate. High levels of DNA fragmentation were associated with low blastulation and pregnancy rates (per transfer); however, fertilization rate was not affected. Samples with higher levels of DNA fragmentation were associated with higher levels of DNA fragmentation in blastomeres without activating the apoptotic pathway (9.1% vs. 15.9%) (p<0.05). Blastomeres from samples with high DNA fragmentation activated the apoptotic pathway in higher levels than samples with TUNEL <15% (16.4% vs. 21.9%) (p<0.05). CONCLUSION: Sperm DNA fragmentation was negatively correlated with blastulation and pregnancy rates even in good quality oocytes. High levels of DNA damage promote embryo arrest and induce the activation of the apoptotic pathway.

Cleavage stage versus blastocyst stage embryo transfer in assisted reproductive technology.

BACKGROUND: Advances in cell culture media have led to a shift in in vitro fertilisation (IVF) practice from cleavage stage embryo transfer to blastocyst stage transfer. The rationale for blastocyst transfer is to improve both uterine and embryonic synchronicity and enable self selection of viable embryos, thus resulting in better live birth rates. OBJECTIVES: To determine whether blastocyst stage (day 5 to 6) embryo transfers improve the live birth rate, and other associated outcomes, compared with cleavage stage (day 2 to 3) embryo transfers. SEARCH METHODS: We searched the Cochrane Gynaecology and Fertility Group Specialised Register of controlled trials, Cochrane Central Register of Controlled Trials (CENTRAL; the Cochrane Library; 2016, Issue 4), MEDLINE, EMBASE, PsycINFO, CINAHL, and Bio extracts from inception to 4th April 2016. We also searched registers of ongoing trials and the reference lists of studies retrieved. SELECTION CRITERIA: We included randomised controlled trials (RCTs) which compared the effectiveness of blastocyst versus cleavage stage transfers. DATA COLLECTION AND ANALYSIS: We used standard methodological procedures recommended by Cochrane. Our primary outcomes were live birth and cumulative clinical pregnancy rates. Secondary outcomes were clinical pregnancy, multiple pregnancy, high order pregnancy, miscarriage, failure to transfer embryos, and embryo freezing. We assessed the overall quality of the evidence for the main comparisons using GRADE methods. MAIN RESULTS: We included 27 RCTs (4031 couples or women).The live birth rate following fresh transfer was higher in the blastocyst transfer group (odds ratio (OR) 1.48, 95% confidence interval (CI) 1.20 to 1.82; 13 RCTs, 1630 women, I(2) = 45%, low quality evidence) following fresh transfer. This suggests that if 29% of women achieve live birth after fresh cleavage stage transfer, between 32% and 42% would do so after fresh blastocyst stage transfer.There was no evidence of a difference between the groups in rates per couple of cumulative pregnancy following fresh and frozen-thawed transfer after one oocyte retrieval (OR 0.89, 95% CI 0.64 to 1.22; 5 RCTs, 632 women, I(2) = 71%, very low quality evidence).The clinical pregnancy rate was also higher in the blastocyst transfer group, following fresh transfer (OR 1.30, 95% CI 1.14 to 1.47; 27 RCTs, 4031 women, I(2) = 56%, moderate quality evidence). This suggests that if 36% of women achieve clinical pregnancy after fresh cleavage stage transfer, between 39% and 46% would do so after fresh blastocyst stage transfer.There was no evidence of a difference between the groups in rates of multiple pregnancy (OR 1.05, 95% CI 0.83 to 1.33; 19 RCTs, 3019 women, I(2) = 30%, low quality evidence), or miscarriage (OR 1.15, 95% CI 0.88 to 1.50; 18 RCTs, 2917 women, I(2) = 0%, low quality evidence). These data are incomplete as under 70% of studies reported these outcomes.Embryo freezing rates were lower in the blastocyst transfer group (OR 0.48, 95% CI 0.40 to 0.57; 14 RCTs, 2292 women, I(2) = 84%, low quality evidence). This suggests that if 60% of women have embryos frozen after cleavage stage transfer, between 37% and 46% would do so after blastocyst stage transfer. Failure to transfer any embryos was higher in the blastocyst transfer group (OR 2.50, 95% CI 1.76 to 3.55; 17 RCTs, 2577 women, I(2) = 36%, moderate quality evidence). This suggests that if 1% of women have no embryos transferred in (planned) fresh cleavage stage transfer, between 2% and 4% will have no embryos transferred in (planned) fresh blastocyst stage transfer.The evidence was of low quality for most outcomes. The main limitation was serious risk of bias, associated with failure to describe acceptable methods of randomisation, and unclear or high risk of attrition bias. AUTHORS' CONCLUSIONS: There is low quality evidence for live birth and moderate quality evidence for clinical pregnancy that fresh blastocyst stage transfer is associated with higher rates than fresh cleavage stage transfer. There was no evidence of a difference between the groups in cumulative pregnancy rates derived from fresh and frozen-thawed cycles following a single oocyte retrieval, but the evidence for this outcome was very low quality. Thus, although there is a benefit favouring blastocyst transfer in fresh cycles, it remains unclear whether the day of transfer impacts on cumulative live birth and pregnancy rates. Future RCTs should report rates of live birth, cumulative live birth, and miscarriage to enable couples or women undergoing assisted reproductive technology (ART) and service providers to make well informed decisions on the best treatment option available.

Correlation between Cytoplamic Oocyte Maturation and Chromosomal Aneuploidies - Impact on fertilization, embryo quality and pregnancy.

OBJECTIVE: To establish the relationship between oocyte cytoplasmic maturation and its chromosomal status and determine the effect of this feature over the reproductive outcome in patients with sub-optimal fertilization in ART. METHODS: Fifty couples who underwent ART were selected. From nineteen patients, 22 metaphase II-MII and 18 failed-fertilized oocytes after ICSI were studied. The first polar body was collected for chromosomal analysis by aCGH. Oocytes were processed by immunocytochemistry (ICC) to determine oocyte maturation: assessment of inactive MPF status and the conformation-alignment of the metaphase plate.Other 31 couples presented sub-optimal fertilization (<50%) after ICSI, and failed-fertilized oocytes were studied by ICC. Two groups were conformed according to the main feature observed: A) cytoplasmic immaturity and sperm premature chromosome condensation and B) sperm nuclear decondensation failure with mature cytoplasm. RESULTS: Regarding MII mature oocytes, 87% had a normal metaphase plate and 84% were chromosomally normal. Contrary, immature oocytes presented abnormal metaphase plate (86%) and just 33% were euploid. In failed-fertilized oocytes: 100% of mature oocytes had a normal metaphase plate and 71% were euploid. When oocytes were cytoplasmic immature, 37% of them were normal (metaphase plate) and 50% were chromosomally normal.The global rate of aneuploidies and metaphase plate disarrangements in immature oocytes (MII+failed-fertilized) were significantly higher than mature oocytes (P<0.05).In patients with sub-optimal fertilization, the percentage of top quality embryos and pregnancy rate was significantly higher in group B (P<0.05). CONCLUSION: Oocyte cytoplasmic immaturity is related to metaphase plate anomalies and aneuploidies. Fertilized oocytes, from a cohort with sub optimal fertilization with cytoplasmic immaturity, had poorer reproductive outcomes.

Relationship Between Sperm DNA Fragmentation and Nuclear Vacuoles.

OBJECTIVE: The aim of the present study is to assess the correlation between the presence, quantity and size of nuclear vacuoles and DNA damage and chromatin status in sperm samples of men who underwent to assisted reproduction technology. METHODS: Forty six males who underwent to assisted reproductive technology (ART) were considered. According to their latest semen analysis (<3 months), were grouped into: (A) strict morphology index ≤4% (26) and (B) strict morphology index ≥14% (20). Motile sperm were selected by density gradient, and MSOME study was conducted to assess the number and size of nuclear vacuoles. DNA fragmentation (TUNEL) and DNA strand status (acridine orange) were assessed over the selected spermatozoa accordingly to their vacuole pattern. RESULTS: In group A, sperm without vacuoles (1°) have similar levels of DNA fragmentation (TUNEL) in compare to the rest of observed patterns (2°- 6°). Regarding to AO, spermatozoa with large or several vacuoles that cover more than 30-50% of the nuclear surface are AO+, but not necessarily TUNEL positive. The first three patterns of vacuoles patterns had lower levels of AO in compare to grades 4° and 6°. In group B, those sperm with one or more vacuoles greater than 30%-50% (4° and 6°), had a significant increase in TUNEL values, in relation to group 1°- 3°. Considering AO, it was found that the 4° and 6° pattern had a significantly elevated level of this marker, as same of group A (P <0.05). CONCLUSIONS: There is no relationship between the greater number and size of sperm vacuoles with high levels of DNA fragmentation in patients with severe teratozoospermia (Kruger <4%). Conversely, this relationship is evident in normal semen samples (normal morphology. Sperm selection by IMSI technique, to select non-fragmented sperm in patients with Kruger <4%, is not necessarily secured when non-vacuolated sperm is selected.

Changes in DNA fragmentation during sperm preparation for intracytoplasmic sperm injection over time.

OBJECTIVE: To compare the DNA fragmentation of semen samples established by terminal deoxynucleotide transferase-mediated dUTP nick-end labeling (TUNEL) after incubation in polyvinylpyrrolidone (PVP) and hyaluronic acid (HA) for different time periods. DESIGN: Comparative prospective study. SETTING: Center for reproductive medicine. PATIENT(S): Twenty-seven semen samples from infertile patients. INTERVENTION(S): None. METHODS: Semen analysis and DNA fragmentation assays (TUNEL) were performed. Two groups were established: A) normal TUNEL (<20%); and B) Abnormal TUNEL (≥ 20%). TUNEL was performed in neat (T0), postgradient (TG), 1-hour postgradient (TG1), and 2-hour postgradient (TG2) samples and in TG2 samples after 0.5, 1.0, and 1.5 hours of incubation in PVP or HA. RESULT(S): TUNEL levels were significantly reduced after gradient separation compared with neat values. In group A, TUNEL levels were significantly higher in the TG2 + 1.5 hours in PVP and HA samples but did not reach abnormal levels. In group B, TUNEL levels were significantly higher in the TG2 + 1 hour in PVP and HA samples. CONCLUSION(S): Sperm DNA fragmentation significantly decreased after centrifugation gradient, regardless of the initial levels of the sample. Samples with TUNEL ≥ 20% were more susceptible to a significant increase in DNA fragmentation over time, with similar increases being observed over time for samples that were incubated in HA or PVP. These data may be relevant for sperm preparation for intracytoplasmic sperm injection.

Acrosomal biogenesis in human globozoospermia: immunocytochemical, ultrastructural and proteomic studies.

BACKGROUND: Acrosome biogenesis is a key event in sperm differentiation that depends on the proper interaction between the Golgi complex and the nuclear envelope of early spermatids. We studied the development, structure and biochemical characteristics of human acrosomes in germ cells and spermatozoa from testicular biopsies and semen samples of fertile men and patients with acrosomeless spermatozoa (globozoospermia). A set of proteins collectively known as the perinuclear theca (PT), which has been related to acrosomal development in many mammalian species, were also investigated. METHODS: We evaluated spermatozoa from five males with globozoospermia and six fertile men, and immature germ cells from testicular biopsies of one globozoospermic patient and three men with obstructive azoospermia. Samples were assessed by transmission electron microscopy, immunofluorescence microscopy, ultrastructural immunocytochemistry and proteomic analysis by western blot. RESULTS: In normal spermiogenesis, the development of the acrosome depends on the correct formation of Golgi-derived proacrosomal vesicles and simultaneous modifications in the nuclear envelope. PT proteins are consistently found in proacrosomic vesicles, localize underneath the acrosome and expand over the nuclear surface along acrosome biogenesis. In fertile men, the PT is composed of six proteins, similar to those previously described for other mammals (16, 22, 29, 34, 50 and 68 kDa). In globozoospermia, abnormal proacrosomal vesicles and paranuclear multivesicular and multilamellar structures were observed that resulted in acrosomes insufficiently developed or detached from the nuclear envelope. PT proteins, dissociated from the acrosomes, were ectopically localized in the cytoplasm. Proteomic analysis showed a significant decrease in all six PT proteins. CONCLUSIONS: The alterations observed during early acrosome biogenesis in globozoospermia are due to anomalous development of Golgi-derived proacrosomic vesicles, failure of PT proteins to properly associate with the nuclear surface and significant deficiencies in specific PT components that are necessary for proper acrosome formation, implantation and expansion over the spermatid nucleus.

Tales of the tail and sperm head aches: changing concepts on the prognostic significance of sperm pathologies affecting the head, neck and tail.

This article presents an update on the variable prognostic significance of different sperm pathologies in patients with severe male factor infertility due to morphology and motility disorders. Severe asthenozoospermia is one of the leading causes of male infertility as spermatozoa cannot reach the oocyte and/or penetrate normally. Identifying structural causes of sperm immotility was of great concern before the advent of intracytoplasmic sperm injection (ICSI), because immotility was the limiting factor in the treatment of these patients. In these cases, in vitro methods are used to identify live spermatozoa or stimulate sperm motility to avoid selection of non-viable cells. With these advances, fertilization and pregnancy results have improved dramatically. The identification of genetic phenotypes in asthenozoospermia is important to adequately inform patients of treatment outcomes and risks. The one sperm characteristic that seriously affects fertility prognosis is teratozoospermia, primarily sperm head and neck anomalies. Defects of chromatin condensation and acrosomal hypoplasia are the two most common abnormalities in severe teratozoospermia. The introduction of microscopic methods to select spermatozoa and the development of new ones to evaluate sperm quality before ICSI will assure that ultrastructural identification of sperm pathologies will not only be of academic interest, but will also be an essential tool to inform treatment choice. Herein, we review the differential roles played by sperm components in normal fertilization and early embryo development and explore how assisted reproductive technologies have modified our concepts on the prognostic significance of sperm pathologies affecting the head, neck, mid-piece and tail.

The nuclear mitotic apparatus (NuMA) protein: localization and dynamics in human oocytes, fertilization and early embryos.

The oocyte's meiotic spindle is a dynamic structure that relies on microtubule organization and regulation by centrosomes. Disorganization of centrosomal proteins, including the nuclear mitotic apparatus (NuMA) protein and the molecular motor complex dynein/dynactin, can lead to chromosomal instability and developmental abnormalities. The present study reports the distribution and function of these proteins in human oocytes, zygotes and early embryos. A total of 239 oocytes, 90 zygotes and discarded embryos were fixed and analyzed with confocal microscopy for NuMA and dynactin distribution together with microtubules and chromatin. Microtubule-associated dynein-dependent transport functions were explored by inhibiting phosphatase and ATPase activity with sodium-orthovanadate (SOV). At germinal vesicle (GV) stages, NuMA was dispersed across the nucleoplasm. After GV breaks down, NuMA became cytoplasmic before localizing at the spindle poles in metaphase I and II oocytes. Aberrant NuMA localization patterns were found during oocyte in vitro maturation. After fertilization, normal and abnormal pronuclear stage zygotes and embryos displayed translocation of NuMA to interphase nuclei. SOV treatment for up to 2 h induced lower maturation rates with chromosomal scattering and ectopic localization of NuMA. Accurate distribution of NuMA is important for oocyte maturation, zygote and embryo development in humans. Proper assembly of NuMA is likely necessary for bipolar spindle organization and human oocyte developmental competence.

Healthy baby born after reduction of sperm DNA fragmentation using cell sorting before ICSI.

Magnetic activated cell sorting (MACS) with annexin V microbeads recognizes externalized phosphatidylserine (PS) residues on the surface of apoptotic spermatozoa. The successful use of this novel technique applied to a highly apoptotic semen sample before performing intracytoplasmic sperm injection (ICSI) is reported here. The use of annexin V microbeads for selecting non-apoptotic spermatozoa seems to reduce the percentage of altered cells, improving the chance of pregnancy after ICSI.

Biogenesis of the sperm head perinuclear theca during human spermiogenesis.

We analyzed the appearance and localization of the sub-acrosomal perinuclear theca (PT) during human spermiogenesis. The PT is tightly associated with acrosomal biogenesis.