Study question What is the optimal endometrial preparation protocol for a frozen embryo transfer (FET)? Summary answer Although the optimal endometrial preparation protocol for FET needs further research and is yet to be determined, we propose a standardized timing strategy based on the current available evidence which could assist in the harmonization and comparability of clinic practice and future trials. What is known already Amid a continuous increase in the number of FET cycles, determining the optimal endometrial preparation protocol has become paramount to maximize ART success. In current daily practice, different FET preparation methods and timing strategies are used. Study design, size, duration This is a review of the current literature on FET preparation methods, with special attention to the timing of the embryo transfer. Participants/materials, setting, methods Literature on the topic was retrieved in PubMed and references from relevant articles were investigated until June 2017. Main results and the role of chance The number of high quality randomized controlled trials (RCTs) is scarce and, hence, the evidence for the best protocol for FET is poor. Future research should compare both the pregnancy and neonatal outcomes between HRT and true natural cycle (NC) FET. In terms of embryo transfer timing, we propose to start progesterone intake on the theoretical day of oocyte retrieval in HRT and to perform blastocyst transfer at hCG + 7 or LH + 6 in modified or true NC, respectively. Limitations reasons for caution As only a few high quality RCTs on the optimal preparation for FET are available in the existing literature, no definitive conclusion for benefit of one protocol over the other can be drawn so far. Wider implications of the findings Caution when using HRT for FET is warranted since the rate of early pregnancy loss is alarmingly high in some reports. Study funding/competing interest(s) S.M. is funded by the Research Fund of Flanders (FWO). H.T. and C.B. report grants from Merck, Goodlife, Besins and Abbott during the conduct of the study. Trial registration number Not applicable.

/pdf/frozen-embryo-transfer-a-review-on-the-optimal-endometrial-49yg13r793.pdf

Frozen embryo transfer: a review on the optimal endometrial preparation and timing.

Generating new life in animals by sexual reproduction depends on adequate communication between mature and competent male and female gametes. Ion channels are instrumental in the dialogue between sperm, its environment, and the egg. The ability of sperm to swim to the egg and fertilize it is modulated by ion permeability changes induced by environmental cues and components of the egg outer layer. Ca(2+) is probably the key messenger in this information exchange. It is therefore not surprising that different Ca(2+)-permeable channels are distinctly localized in these tiny specialized cells. New approaches to measure sperm currents, intracellular Ca(2+), membrane potential, and intracellular pH with fluorescent probes, patch-clamp recordings, sequence information, and heterologous expression are revealing how sperm channels participate in fertilization. Certain sperm ion channels are turning out to be unique, making them attractive targets for contraception and for the discovery of novel signaling complexes.

Calcium Channels and Ca2+ Fluctuations in Sperm Physiology

http://directory.umm.ac.id/Data%20Elmu/jurnal/A/Animal%20Reproduction%20Science/Vol63.Issue3-4.Nov2000/2042.pdf

Effect of freezing and thawing rates on the post-thaw viability of boar spermatozoa frozen in FlatPacks and Maxi-straws.

Transfer of frozen-thawed embryos is usually carried out in a natural cycle or in a programmed cycle in which the endometrium is exogenously stimulated following down-regulation of the hypophysis. To analyse the possibility that the programmed cycle for embryo transfer can still be hormonally manipulated without the use of gonadotrophin-releasing hormone agonist (GnRHa) we have conducted a prospective randomized study that compared the outcome of frozen-thawed embryo transfer cycles using micronized 17beta-oestradiol and micronized progesterone preparations with and without the concomitant use of GnRHa. One hundred and six patients were randomly divided into two groups. In group A (53 patients) 4 mg/day of micronized 17beta-oestradiol was initiated following down-regulation of hypophysis. In group B (53 patients) oestrogen stimulation started on day 1 of the cycle without prior pituitary down-regulation using a dose of 6 mg/day for 7 days. In both groups, micronized progesterone in a dose of 900 mg/day was administered vaginally after at least 12 days of oestrogen stimulation. Embryo transfer embryo transfer took place 48-72 h thereafter according to the cryopreserved embryonic stage. Overall, none of the patients had any follicular development and only one cycle in group B had to be cancelled because of premature progesterone secretion. The two groups did not differ in age (31+/-5.6 and 31+/-5.0 years), number of embryos transferred per patient (3.4+/-1.2 and 3.3+/-1.0), and day of progesterone initiation (15+/-2.2 and 15+/-1.9 for groups A and B respectively). The endometrial thickness on the day of progesterone initiation was comparable in both groups (11 +/-1.6 and 10+/-1.6 mm for groups A and B respectively). Similarly, the pregnancy rate per embryo transfer and implantation rate in group A (26.4% and 9.5%) were comparable to those of group B (21.1% and 9%). These results indicate that programmed cycles can be successfully applied by administering a high dose of micronized 17beta-oestradiol starting on day 1 of the cycle. Compared to GnRHa programmed cycles, this approach is simpler, more convenient for both the patient and medical staff, and results in a similar success rate at a lower cost.

Transfer of frozen-thawed embryos in artificially prepared cycles with and without prior gonadotrophin-releasing hormone agonist suppression: a prospective randomized study.

BACKGROUND: The formation of functional ovarian cysts has been recognized as one of the side effects of GnRH agonist administration. The formation of cysts during IVF treatment may be of no clinical significance or may negatively influence its outcome. The objective of this study was to determine the incidence of ovarian cyst formation following GnRH agonist administration and to examine their effect on IVF outcome. METHODS: A prospective study of 1317 IVF patients who developed one or more functional ovarian cysts of 15 mm following GnRH agonist treatment was performed. Transvaginal ultrasonographic-guided cyst aspiration was carried out in 76 randomly allocated patients out of 122 patients who were found to have functional ovarian cysts before starting ovarian stimulation with gonadotropins. RESULTS: The incidence of follicular cyst formation was 9.3%. Cyst cycles in comparison with noncyst cycles had significantly elevated day 3 basal FSH (mean ± SD of 8.3 ± 3.2 versus 5.3 ± 2.6 mIU/ml, P < 0.05) and required more ampoules of gonadotropins (46.3 ± 16.5 versus 35 ± 14.6, P <0.01). Furthermore, they showed a statistically significant decrease in the quality and number of oocytes retrieved, fertilization rate, number and quality of embryos, implantation and pregnancy rates, with a significant increase in cancellation and abortion rates. Patients with bilateral cysts had a significantly lower number of oocytes and embryos retrieved, with a lower proportion of metaphase II oocytes. They also had a higher proportion of poor quality embryos. Cyst aspiration was not associated with a significant difference in the above parameters. CONCLUSIONS: The incidence of cyst formation during GnRH agonist treatment is lower than previously reported. In such cases, the quality of oocytes and embryos were significantly compromised, with a significant increase in the cycle cancellation rate and a decrease in the implantation and pregnancy rates. Neither conservative management nor cyst aspiration improved the IVF outcome.

/pdf/ovarian-cyst-formation-following-gnrh-agonist-administration-1uk32b6mta.pdf

Ovarian cyst formation following GnRH agonist administration in IVF cycles: incidence and impact

Baseline cyst formation after luteal phase gonadotropin-releasing hormone agonist administration is linked to poor in vitro fertilization outcome.

Purpose:Our purpose was to evaluate sperm motility and viability and the maintenance of these parameters in already cryopreserved semen samples following repeated freezing/thawing cycles.

Methods:Human spermatozoa were subjected to five cycles of cryopreservation/thawing. Recovery of sperm motility and viability and the proportion of viable nonmotile sperm were determined up to 6 hr after thaw.

Results:Sperm motilities (prefreeze motility, 70.1%; n = 9 samples) after each of five freeze/thaw cycles were 24.4, 8.0, 3.5, 1.5, and 1.8%. The recovery of sperm viability was higher than that of motility after each cycle: 39.1, 25.3, 22.6, 17.8, and 16.5%. Recoveries of motility and viability were improved if the thawed samples were left in the original cryopreservation medium prior to refreezing vs. if a washing/resuspension step was included. The recovery of sperm motility in the first thawing cycle was indicative of the expected motile sperm recovery in the second thawing cycle.

Conclusions:Cryopreserved semen that is intended to be reused in future assisted reproduction treatments should be thawed only once and aliquoted in the original freezing medium before refreezing. The recovery of sperm motility and viability in the second thawing cycle, thus the applicability of the sample in conventional in vitro fertilization or intracytoplasmic sperm injection may be anticipated in >90% of the samples. In view of intracytoplasmic sperm injection it is important that sperm viability is maintained better than motility; after the first, second, and third thawing cycles the ratios of motile:nonmotile viable sperm were 1:1, 1:4, and 1:7, respectively.

/pdf/optimal-utilization-of-cryopreserved-human-semen-for-16i11fz2a1.pdf

Optimal Utilization of Cryopreserved Human Semen for Assisted Reproduction: Recovery and Maintenance of Sperm Motility and Viability

https://www.fertstert.org/article/S0015-0282(97)00282-3/pdf

Tibor E. Polcz

Papers

Baseline cyst formation after luteal phase gonadotropin-releasing hormone agonist administration is linked to poor in vitro fertilization outcome.

Optimal Utilization of Cryopreserved Human Semen for Assisted Reproduction: Recovery and Maintenance of Sperm Motility and Viability

Improving the intracytoplasmic sperm injection technique by transmembrane electric potential monitoring.