Can Oocyte Diameter Predict Embryo Quality?

With the recent increased utilization of oocyte vitrification for the purpose of fertility preservation, information regarding the future fertility potential of the frozen oocytes is mandatory. Nowadays, there is a relative lack of data about prediction of assisted reproductive technique (ART) success relying on the retrieved oocytes. In the present study, we therefore aimed to investigate whether oocyte diameter might predict the quality of the developing embryo. A retrospective, single-center cohort study. Oocytes retrieved following controlled ovarian hyperstimulation cycles during 2016 and incubated in a time-lapse incubator system were analyzed. Oocytes were grouped by mean oocyte diameter (MOD) and incubated for 5 days before the final morphological evaluation done by an expert embryologist. A total of 471 cycles which yielded 3355 metaphase II oocytes were included in the analysis. Embryos developed from oocytes with MOD close to the average (Average 1SD < MOD < Average + 1SD) had increased good-quality blastulation rates compared with embryos that developed from very small or very large oocytes. Oocytes with MOD between 105.96 and 118.69 µm have better probability of becoming top-quality D5 blastocysts (17.1-17.4% grade 1 embryos). There is a correlation between oocyte's MOD and the embryo quality at day 5. The oocytes with near average MOD have a better chance to develop to a good-quality embryo. Therefore, the study suggests that MOD might serve as a predictor for embryo grading at day 5.

What is the optimal timing of embryo transfer when there are only one or two embryos at cleavage stage?

Today, most IVF programs have moved to blastocyst transfer but there is still uncertainty regarding when to transfer if there are only one or two embryos at the cleavage stage. The aim of this study was to compare the pregnancy rate of day 3 transfers vs. blastocyst stage transfers in patients who had only one or two embryos on day 3. We conducted a retrospective study of 102 patients with one or two cleavage stage embryos that had their embryos transferred on day 3 and 429 patients had their embryos cultured to day 5 for transfer. The number of mature oocytes (4.0 vs 4.6, p = NS) and number of cleavage stage embryos on day 3 was similar in the two groups (1.3 vs. 1.5, p = NS). The clinical pregnancy rate per retrieval (22% vs. 24.6%, p= NS) and the ongoing pregnancy rate per retrieval (20% vs. 20.2%, p = NS) was comparable between the groups. Fifty seven (13.2%) of the patients had cleavage embryo arrest and did not have an embryo to transfer on day 5. We conclude that the cumulative pregnancy rate is the same for patients with 1-2 cleavage stage embryos regardless of whether the embryo is transferred on day 3 or day 5.

Sub-endometrial contractility or computer-enhanced 3-D modeling scoring of the endometrium before embryo transfer: are they better than measuring endometrial thickness?

PURPOSE: Recent studies have focused on transvaginal ultrasound measurement (TVUS) of sub-endometrial contractility and computer-enhanced 3-D modeling scoring of the endometrium prior to embryo transfer (ET).The aim of this study was to compare pregnancy outcome of patients who performed the 3-D scoring or the sub-endometrial measurement prior to the ET with patients that did not perform those procedures. METHODS: A single center retrospective cohort study of 635 freeze/thaw cycles of blastocysts vitrified on day 5 and transferred between January 2016 and August 2016. RESULTS: We compared the patients who performed 3-D scoring with the control group and found comparable patients' characteristics, clinical pregnancy rates (42% vs. 44.3, p = NS, respectively), and ongoing pregnancy rates (31.7% vs. 33.9%, p = NS).We then compared the patients who performed the sub-endometrial wave measurements with the control group and found similar findings. The clinical pregnancy rate (38.2% vs. 44.3, p = NS, respectively) and the ongoing pregnancy rate (30.8% vs. 33.9%) were comparable between the two groups. We performed a regression analysis to examine the independent contribution of different variables to the ongoing pregnancy rates. Both the 3-D and the wave count procedures were not found to have any influence on the ongoing pregnancy rates. CONCLUSIONS: Although new ultrasonic methods of evaluating the endometrium have been proposed during the last years, these methods have not been shown to improve the pregnancy rates compared to the original method of assessing the endometrium by measuring the endometrial thickness.

Developmental potential of slow-developing embryos: day-5 morulae compared with day-5 cavitating morulae.

OBJECTIVE: To describe and compare the ongoing pregnancy rate between morulae and cavitating morulae (CAVM) transferred on day 5, to describe and compare the blastulation rate between day 5 morulae and CAVM, and to describe the pregnancy rate of these slow-developing blastocysts during a frozen embryo transfer (FET) cycle. DESIGN: Retrospective cohort study. SETTING: Single tertiary care medical center. PATIENT(S): Delayed-development embryos: 3,321 cycles that included 10,304 embryos on day 5 that were cultured until day 6. INTERVENTION(S): Development of morula and CAVM to the blastocyst stage. MAIN OUTCOME MEASURE(S): Blastulation rate. RESULT(S): The fresh embryo transfers comprised 186 patients with 82 embryos at the morula stage and 104 embryos at the CAVM stage. The pregnancy rate (15.8% vs. 21.1%) and the ongoing pregnancy rate (15.8% vs. 17.3%) were comparable between the groups. The study group included 10,304 day-5 delayed embryos: 5,395 morulae and 4,909 CAVM on day 5. The blastulation rate was statistically significantly higher in the CAVM group compared with the morula group (39.2% vs. 20.4%). We included 201 FET cycles: 77 warmed blastocysts that developed from a morula on day 5 and 124 warmed blastocysts that developed from CAVM on day 5. The clinical pregnancy rate was comparable between the two groups per embryo transfer (21.3% vs. 24.7%). CONCLUSION(S): Transferring of fresh, slow-developing embryos seems to improve the cycle outcomes compared with culturing for another day and then vitrifying and thawing later.

Prolonged culture of blastocysts after thawing as a tool for improving prediction of success.

PURPOSE: A few years ago, we started to use a new freeze-thaw protocol for the frozen embryo transfer cycles. Instead of thawing the embryos 2-4 h prior to the transfer, we started thawing the embryos 20-22 h prior to the transfer. The aim of this study was to compare the pregnancy rate in cases of embryos that continued to develop in the post-thawing culture to that of embryos that did not. METHODS: A retrospective cohort study of blastocyst freeze/thaw cycles vitrified on day 5, thawed and transferred after 20-22 h in the culture, between January 2012 and December 2016. RESULTS: A total of 375 patients were included in the analysis. Two hundred twenty-eight embryos graded as good, 87 graded as fair, and 60 graded as poor embryos were transferred. The clinical pregnancy rate (50% vs. 19.5% vs 3.3% p < 0.01) and the ongoing pregnancy rate (38.5% vs. 13.6% vs 1.7% p < 0.01) were higher in cases of good embryo quality compared with fair and poor-quality embryos, respectively. For good embryos, progressing to a better grade during the culture did not change the clinical pregnancy rate (51.3% vs. 46.2% p = NS) or the ongoing pregnancy rate (38.5% vs. 37.5% p = NS). For fair embryos, progressing to a better grade during the culture resulted in a higher clinical pregnancy rate (25.4% vs 9% p = 0.05). CONCLUSIONS: The development of the fair embryos in the culture has a highly positive impact on the pregnancy rate and this factor should be taken into consideration before deciding how many embryos to transfer.

Does the endometrial receptivity array really provide personalized embryo transfer?

PURPOSE: The aim of the present study was to determine the percentage of infertility patients who are diagnosed with a non-receptive endometrium according to the endometrial receptivity array (ERA) test and to examine whether adjusting the embryo transfer day according to the proposed shift in the window of implantation improves the pregnancy rate compared to non-ERA-tested patients. METHODS: A single-center retrospective cohort study, including 53 consecutive good prognosis patients (0-2 previous frozen embryo transfers) admitted to our IVF unit for a mock cycle prior to their frozen day-5 embryo (blastocyst) transfer cycle. The mock cycle included an endometrial biopsy for both the ERA test and histological assessment by the Noyes criteria (study group). The next cycle frozen embryo transfer (FET) in the study group was adjusted according to the ERA results. The control group consisted of patients who underwent FET cycles at our clinic during the same period, without performing the endometrial biopsy and ERA testing. RESULTS: During the study period, 503 patients (control group) underwent FET cycles without performing the ERA testing and 41 patients had FET following an ERA test. There were no between-group differences in patients' age, number of previous transfers, endometrial thickness, number of transferred embryos, and ongoing pregnancy rates (35.2 vs. 39%, respectively, p = NS). Out of the 53 patients who performed the ERA test before their first or second FET, five endometrial samples (9.4%) were found to be post-receptive, 29 (54.7%) pre-receptive, and only 19 samples (35.8%) were receptive. Women in the study group with pre- or post-receptive endometrium on ERA testing, the appropriate adjustment in timing of FET according to the ERA test resulted in a 33.3% pregnancy rate, which is comparable to the 35.2% background ongoing pregnancy rate of the control group. CONCLUSIONS: Performing the ERA test in a mock cycle prior to a FET does not seem to improve the ongoing pregnancy rate in good prognosis patients. Further large prospective studies are needed to elucidate the role of ERA testing in both good prognosis patients and in patients with recurrent implantation failure.

The VEGF and PEDF levels in the follicular fluid of patients co- treated with LETROZOLE and gonadotropins during the stimulation cycle.

BACKGROUND: Previous studies have shown that androgens, in addition to serving as precursors for ovarian estrogen synthesis, also have a fundamental role in primate ovarian follicular development by augmentation of FSH receptor expression on granulosa cells. Recent studies have shown that aromatase inhibitor, letrozole, improves ovarian response to FSH in normal and poor responder patients, possibly by increasing intraovarian androgen levels. Studies in mice also showed an effect of letrozole to increase pigment epithelium-derived factor (PEDF) and to lower vascular epithelial growth factor (VEGF), which might be expected to reduce the risk of ovarian hyperstimulation syndrome (OHSS) with stimulation. The aim of this study was to compare the VEGF and PEDF levels in the follicular fluids of normal responders treated with letrozole and gonadotropins during the ovarian stimulation with patients treated with gonadotropins only. METHODS: A single center, prospective clinical trial. We collected follicular fluid from 26 patients, on a GnRH antagonist protocol, dual triggered with hCG and GnRH agonist. The patients in one group were co-treated with letrozole and gonadotropins during the ovarian stimulation and the patients in the other group were treated with gonadotropins only. VEGF, PEDF, estrogen, progesterone and testosterone levels were measured by ELISA kits. RESULTS: The age of the patients, the total dose of gonadotropins and the number of oocytes were comparable between the two groups. In the follicular fluid, the estrogen levels (2209 nmol/l vs. 3280 nmol/l, p = 0.02) were significantly decreased, and the testosterone levels (246.5 nmol/l vs. 40.7 nmol/l, p < 0.001) were significantly increased in the letrozole group compared to the gonadotropin only group. The progesterone levels (21.4 µmol/l vs. 17.5 p = NS) were comparable between the two groups. The VEGF levels (2992 pg/ml vs. 1812 pg/ml p = 0.02) were significantly increased and the PEDF levels (9.7 ng/ml vs 17.3 ng/ml p < 0.001) were significantly decreased in the letrozole group. CONCLUSIONS: Opposite to observations in the mouse, we found that VEGF levels were increased and PEDF levels were decreased in the follicular fluid in patients treated with letrozole during the stimulation cycles. Further investigation is required to determine if patients treated with letrozole during the IVF stimulation protocol are at increased risk for developing OHSS as a result of these findings.

Recent advances in in vitro fertilization.

The field of assisted reproductive technology is rapidly progressing with many new advances in the last decade. The present review discusses methods to improve oocyte quality in older women and new stimulation protocols that may improve the number of mature oocytes retrieved during an in vitro fertilization cycle. We will discuss the present use of pre-implantation genetic screening (PGS) and finally focus on some new methods to determine endometrial receptivity. The focus of this review is to point out areas of technology that may be controversial or are new enough to require proper controlled studies for validation.

Does daily co-administration of letrozole and gonadotropins during ovarian stimulation improve IVF outcome?

BACKGROUND: For the last year we have been treating normal responders with gonadotropins and letrozole during the whole stimulation in order to improve response to FSH by increasing the intrafollicular androgen concentration, and to reduce circulating estrogen concentrations. The aim of this study was to compare the IVF outcome of normal responders treated with letrozole and gonadotropins during ovarian stimulation with patients treated with gonadotropins only. METHODS: A single centre retrospective cohort study of 174 patients (87 in each group). RESULTS: The age of the patients was comparable between the groups. Estradiol levels were significantly higher in the control group (6760 pmol/L vs. 2420 pmol/L respectively, p < 0.01), and the number of follicles ≥15 mm at the trigger day was significantly lower in the control group (7.9 vs. 10, p = 0.02). The number of retrieved oocytes (10 vs. 14.5, p < 0.01), MII oocytes (7.9 vs. 11.2, p < 0.01) and blastocysts (2.7 vs. 4.0, p = 0.02) was significantly higher in the study group. We found no significant differences in the cumulative pregnancy outcome between the two groups (65.2% vs 58.3% p = NS). CONCLUSIONS: We conclude that co-treatment with letrozole improves the IVF outcome in normal responders in terms of increased number of blastocysts obtained without increasing the pregnancy rate or the risk of OHSS.