Importance of embryo transfer technique in maximizing assisted reproductive outcomes

Sonographer-guided frozen embryo transfer vs ultrasound-assisted frozen embryo transfer - A randomised controlled study

BACKGROUND

The use of ultrasound to guide placement of the embryo during in vitro fertilisation (IVF) is important, but there are times where a good image cannot be obtained. Having a trained sonographer perform the ultrasound may therefore improve the success of embryo transfer.

AIM

To determine whether the routine use of a sonographer to guide embryo transfer is superior to standard care.

MATERIALS AND METHODS

Randomised, controlled, prospective clinical study in a private infertility clinic. There were 113 women aged <38 years undergoing frozen embryo transfer (donor egg/embryo excluded) who were randomised to sonographer-guided embryo transfer or standard care (the doctor performs an ultrasound prior to embryo transfer and the patient holds the ultrasound probe). The primary outcome was visualisation of the air bubble, and secondary outcomes were distance of the air bubble from the fundal endometrium, pregnancy rate (gestational sac on ultrasound at seven weeks) and live birth rate.

RESULTS

The bubble was visualised in 100% of embryo transfers with a sonographer compared to 83% in the ultrasound-assisted group, and this was statistically significant (P < 0.01). No statistically significant differences were found in terms of distance from the fundal endometrium or in pregnancy rate and live birth rate.

CONCLUSION

Sonographer-guided embryo transfer leads to statistically higher rates of visualisation of the air bubble compared to ultrasound-assisted transfer.

Embryo Transfer Procedural Parameters Do Not Predict IVF Cycle Outcome

BACKGROUND

this study aims to assess the effect of embryo transfer (ET) performance parameters of a technical nature on IVF outcome.

METHODS

A total of 1417 ETs from a single IVF center were included in this prospective observational study. The parameters investigated were as follows: the presence of cervical mucus post catheter withdrawal, the presence of blood, catheter reload, the employment of a tenaculum and stylet, catheter resistance as experienced by the physician and patient discomfort.

RESULTS

When ET performance parameters were associated with clinical outcomes on a singular level, none of the ET parameters presented with any statistical significance. The evaluation of covariates indicated that the number and the quality of transferred embryos, as well as maternal age, exerted a statistically significant effect on clinical outcomes. In a multivariate analysis, only the presence of mucus along with significant catheter resistance presented with statistical significance; however, when adjusting for covariates, this combination showed no statistically significant effect on clinical outcomes.

CONCLUSIONS

the results indicate that the time-consuming process of recording and analyzing ET performance parameters fails to offer any additional value in predicting the cycle's outcome, while factors like embryo quality and number, as well as maternal age, seem to be the sole robust predictive factors of an IVF cycle.

Steps forward in embryo transfer technique: a retrospective study comparing direct versus afterload catheters at different time frames

PURPOSE

To assess whether embryo transfer (ET) technique can influence the clinical pregnancy rate (CPR) and its correlation with the embryo transfer difficulty.

DESIGN

This single center retrospective cohort analysis of fresh and frozen single blastocyst transfers performed between January 2016 and December 2021 included fresh and frozen single blastocyst transfers performed during the study timeframe. Direct technique was the only one used from January 2016 to September 2017. From September 2017 to March 2019, the choice between the two techniques was given by randomization, due to a clinical trial recruitment. From April 2019, only the afterload technique was used. Preimplantation genetic testing cycles and gamete donation procedures and cycles performed with external gametes or embryos were excluded. CPR was the primary outcome, while difficult transfer rate the secondary one. Univariate and multivariate logistic regressions were performed.

RESULTS

During the period, 8,189 transfers were performed. CPR of the afterload group resulted significantly higher compared to the direct group (44.69% versus 41.65%, OR 1.13, 95% CI 1.02-1.25, p = 0.017) and the rate of difficult transfers two-thirds lower (9.06% versus 26.85%, OR 0.27, 95% CI 0.24-0.31, p < 0.001).

CONCLUSION

Our study demonstrated that CPR is significantly affected by the ET technique. In particular, with the afterload protocol, both CPR and easy transfer rates increased.

TRIAL REGISTRATION

http://clinicaltrials.gov registration number: NCT05364528, retrospectively registered on 3rd of May 2022.

Factors Affecting the Outcomes of First in vitro Fertilization and Embryo Transfer: A Retrospective Investigation

Background

The outcome of embryo transfer (ET) is multifactorial. A variety of patient-related, procedural-related, and operator-related factors are known to play a role. This study aims to evaluate the outcomes of ET and determine the factors that affect the outcome.

Methods

The study involved a retrospective design involving 300 first in vitro fertilization and embryo transfer (IVF-ET) cycles between 2011 and 2021. The outcome included 155 unsuccessful cycles and 145 successful IVF-ET leading to pregnancy. The outcomes were examined for different variables, including age, weight, height, body mass index, cause of infertility, number of embryos fertilized during the cycle, day of ET, whether the embryo was frozen, presence of blood or mucus during the procedure, the use of a stylet, tenaculum, uterine sound/dilator, and catheter type. Logistic regression was used to analyze factors affecting the outcomes of ET.

Results

The mean age was 27.84 ± 3.77 years. Patients who had blood during the procedure (32.9% vs 17.2%, p = 0.002), mucus (31% vs 20.7%, p = 0.049), or used the tenaculum (16.8% vs 6.9%, p = 0.012) were more likely to have unsuccessful IVF-ET. Logistic regression to adjust for related factors revealed that the presence of blood (AOR = 2.21, 95% CI 1.04 to 4.66, p = 0.038) during the ET had a higher likelihood of an unsuccessful outcome.

Conclusion

This study showed that the presence of blood during the ET cycle influenced clinical pregnancy. This highlights the importance of performing the procedure under atraumatic conditions.

Level of Evidence

Level III; retrospective comparative study.

Large-scale retrospective analysis of methodological factors affecting pregnancy rates after embryo transfer for in vitro fertilization

This study aimed to investigate the impact of methodological factors on pregnancy rates after embryo transfer (ET) for in vitro fertilization. This retrospective cross-sectional study was conducted between September 2020 and April 2022. A total of 2048 patients who underwent ultrasonography-guided first frozen embryo transfer (FET) or a fresh ET cycle due to infertility were included in the study. The effects of age, ET protocol (frozen or fresh), preimplantation genetic testing, number of embryos transferred (NET), and embryo fundus distance on pregnancy rate were investigated. The mean age of pregnant patients (31.51 ± 5.28) was significantly lower than that of non-pregnant patients (35.34 ± 6.39) (P < .001). Multiple regression analysis showed that women with lower age (P < .001), higher NET (P < .001), higher embryo fundus distance (P < .001), FET (P < .001), and preimplantation genetic testing (P = .012) had a significantly higher likelihood of pregnancy. Appropriate transfer depth, younger age, euploid embryo transfer, FET, and a higher NET can increase the likelihood of pregnancy. However, multiple factors must be considered when deciding the best protocol for a particular patient, including patient preference, costs and timing.

Effect of retained embryos on pregnancy outcomes of in vitro fertilization: a matched retrospective cohort study

OBJECTIVES

To explore the incidence of retained embryos (REs) in embryo transfer (ET) cycles and its effects on pregnancy outcomes in women undergoing in vitro fertilization (IVF).

METHODS

This was a matched retrospective cohort study involving 29,160 ET cycles conducted from March 2016 to February 2021, in which ET cycles without RE were matched to the RE group at a 2:1 ratio. Clinical pregnancy, implantation, miscarriage, and live birth rates were compared between the with-RE and without-RE groups.

RESULTS

Our study showed that the overall incidence of REs was 0.33% (95/29,160). There was a statistically significant difference in RE rate among the operators (P < 0.001), suggesting that the embryo retention rate may be affected by the individual operator. A total of 95 repeated ET cycles due to RE were included in the study group, and 190 ET cycles without RE were matched to the study group (1:2). There were no significant differences between the RE and matched groups in terms of implantation rate (35.6 vs. 38.0%; P = 0.608), clinical pregnancy rate (47.4 vs. 54.7%; P = 0.240), biochemical pregnancy rate (5.3 vs. 4.7%; P = 0.846), miscarriage rate (11.1 vs. 9.6%; P = 0.781), ectopic pregnancy rate (2.2 vs. 1.9%; P = 1.000) or live birth rate (41.1 vs. 48.9%; P = 0.208).

CONCLUSIONS

The present findings demonstrated that immediate retransfer of REs did not significantly affect IVF outcomes, which may provide counselling information for patients when REs are identified and ET is reattempted. The incidence of REs was associated with the operator who expelled the embryos from the catheter. Attention to detail and frequent assessment of the operator's technique may facilitate avoidance of embryo retention.

Association between oocyte retrieval technique and number of oocytes retrieved

PURPOSE

To assess if there is an optimal oocyte retrieval (OR) technique to retrieve a maximum number of oocytes and mature oocytes (MII).

METHODS

Retrospective cohort study in which nine physicians completed a survey on OR techniques. Number of oocytes/follicle cohort, MIIs/follicle cohort, and MIIs/oocytes retrieved (%MII) were assessed for each technique for patients undergoing OR from 3/2013 to 7/2019. Data were stratified by number of follicles on ultrasound on day of trigger (< 6, 6-10, > 10).

RESULTS

Patient demographics were equivalent between techniques. For < 6 follicles, three techniques resulted in significantly fewer oocyte/follicle (0.97 ± 0.48, 0.95 ± 0.66, and 0.90 ± 0.41) compared to the top-performing technique (TPT) (1.11 ± 0.55). For 6-10 follicles, two techniques resulted in significantly fewer oocyte/follicle (0.95 ± 0.39 and 0.93 ± 0.35) compared to the TPT (1.06 ± 0.42). A different technique had higher %MII (0.77 ± 0.19) compared to two techniques (0.74 ± 0.21 and 0.72 ± 0.22). For > 10 follicles, two techniques resulted in significantly fewer oocyte/follicle (1.01 ± 0.42 and 1.07 ± 0.40) compared to the TPT (1.15 ± 0.41). These two techniques also resulted in fewer MII/follicle (0.75 ± 0.33 and 0.81 ± 0.34 vs. 0.87 ± 0.34). There was no consistent TPT across follicle number groups or for all outcome variables.

CONCLUSIONS

There does not appear to be a clear TPT, even for patients with few follicles. Providers who perform OR in a similar fashion to physicians at our institution should feel confident that those techniques obtain equivalent oocyte yields.

Evidence and consensus on technical aspects of embryo transfer

BACKGROUND

Ultrasound-guided embryo transfer (US-GET) is a widely performed procedure, but standards for the best practice are not available.

OBJECTIVE AND RATIONALE

This document aims to provide an overview of technical aspects of US-GET after considering the published data and including the preparation for the embryo transfer (ET) procedure, the actual procedure, the post-procedure care, associated pathologies, complications and risks, quality assurance and practitioners’ performance.

SEARCH METHODS

A literature search for evidence on key aspects of the ET procedure was carried out from database inception to November 2021. Selected papers (n = 359) relevant to the topic were analysed by the authors. The following key points were considered in the papers: whether ultrasound (US) practice standards were explained, to what extent the ET technique was described and whether complications or incidents and how to prevent such events were reported. In the end, 89 papers could be used to support the recommendations in this document, which focused on transabdominal US-GET.

OUTCOMES

The relevant papers found in the literature search were included in the current document and described according to the topic in three main sections: requirements and preparations prior to ET, the ET procedure, and training and competence for ET. Recommendations are provided on preparations prior to ET, equipment and materials, ET technique, possible risks and complications, training and competence. Specific aspects of the laboratory procedures are covered, in particular the different loading techniques and their potential impact on the final outcomes. Potential future developments and research priorities regarding the ET technique are also outlined.

LIMITATIONS, REASONS FOR CAUTION

Many topics were not covered in the literature review and some recommendations were based on expert opinions and are not necessarily evidence based.

WIDER IMPLICATIONS

ET is the last procedural step in an ART treatment and is a crucial step toward achieving a pregnancy and live birth. The current paper set out to bring together the recent developments considering all aspects of ET, especially emphasizing US quality imaging. There are still many questions needing answers, and these can be subject of future research.

STUDY FUNDING/COMPETING INTEREST(S)

No funding. ADA has received royalties from CRC Press and personal honorarium from Cook, Ferring and Cooper Surgical. The other co-authors have no conflicts of interest to declare that are relevant to the content of this article.

Uterine factors modify the association between embryo transfer depth and clinical pregnancy

The embryo transfer depth may affect the chance of pregnancy. However, embryo dislodging caused by uterine contraction may occur after the transfer. The aim of the retrospective study was to investigate whether the factors associated with uterine contractilities, such as endometrial thickness and progesterone elevation, affect the association between transfer depth and implantation. A total of 7849 fresh transfer cycles on conventional stimulation in a single in vitro fertilization (IVF) center during the period 2013–2015 was reviewed. Patients were categorized according to quartiles of embryo transfer depth (≤ 9 mm, n = 1735, 9.1–11 mm, n = 2557, 11.1–14 mm, n = 1933, ≥ 1.4 mm, n = 1624, respectively). Adjusted for confounding factors, the adjusted odds ratio (aOR) (95% confidence interval, CI) for clinical pregnancy was 0.90 (0.79–1.02), 0.86 (0.74–0.99), and 0.70 (0.60–0.82) respectively in quartiles 2 through 4, comparing with quartile 1. However, the aORs were significantly increased when the endometrial thickness was < 8 mm. In comparison with that in the cycles with a normal endometrial thickness (8–11 mm), the aORs comparing quartiles 2 through 4 with quartile 1 in the cycles with an endometrial thickness < 8 mm increased from 0.78 (95% CI 0.65–0.93), 0.79 (95% CI 0.65–0.97), and 0.64 (95% CI 0.51–0.81) to 1.73 (95% CI 1.21–2.47), 1.04 (95% CI 0.69–1.56), and 1.45 (95% CI 0.91–2.31), respectively. In the cycles with elevated progesterone and blastocyst stage transfer, the aORs comparing quartiles 4 with quartile 1 decreased from 0.73 (95% CI 0.62–0.87) and 0.74 (95% CI 0.63–0.87) to 0.58 (95% CI 0.40–0.84) and 0.42 (95% CI 0.25–0.73) than those in the cycles without. However, only blastocyst transfer showed a significant interaction with transfer depth (p = 0.043). Our data suggested that endometrial thickness and blastocyst transfer significantly affect the association between embryo transfer depth and clinical pregnancy.

Soft Microrobot for Embryo Transfer in Assisted Reproductive Technology

This letter proposes a novel therapeutic approach in assisted reproductive technology (ART) to control the implantation position of after embryo transfer. The system composed of a soft microrobot, a catheter, and a guiding magnet. The microrobot accommodates and transports an embryo into the patient’s uterus and keeps the embryo within the suitable area for implantation. The proposed treatment was demonstrated with the prototype in an obstetric model. This minimally invasive system will increase the pregnancy rate and prevent ectopic pregnancy.

An expert commentary on essential equipment, supplies and culture media in the ART laboratory

The ART laboratory is a complex system designed to sustain the fertilization, survival, and culture of the preimplantation embryo to the blastocyst stage. ART outcomes depend on numerous factors, among which are the equipment, supplies and culture media used. The number and type of incubators also may affect ART results. While large incubators may be more suitable for media equilibration, bench-top incubators may provide better embryo culture conditions in separate or smaller chambers and may be coupled with time-lapse systems that allow continuous embryo monitoring. Microscopes are essential for observation, assessment, and micromanipulation. Workstations provide a controlled environment for gamete and embryo handling and their quantity should be adjusted according to the number of ART cycles treated in order to provide a steady and efficient workflow. Continuous maintenance, quality control and monitoring of equipment is essential and quality control devices such as the thermometer, and pH-meter are necessary to maintain optimal culture conditions. Tracking, appropriate delivery and storage conditions, and quality control of all consumables is recommended so that the adequate quantity and quality is available for use. Embryo culture media have evolved: preimplantation embryos are cultured either by sequential media or single-step media that can be used for interrupted or uninterrupted culture. There is currently no sufficient evidence that any individual commercially-available culture system is better than others in terms of embryo viability. In this review, we aim to analyse the various parameters that should be taken into account when choosing the essential equipment, consumables and culture media systems that will create optimal culture conditions and provide the most effective patient treatment.

Does rotation during catheter withdrawal in embryo transfer increase pregnancy rates?

BACKGROUND

The aim of this study was to determine whether there is a difference in pregnancy rates between groups that we removed directly and removed by rotating the embryo transfer catheter 360°.

METHODS

The study group consisted of 552 patients who were withdrawn by 360° rotation and 797 patients who were withdrawn without catheter rotation. All patients underwent one or two fresh ETs on day 3 or 5. Groups were compared in terms of cycle characteristics and clinical pregnancy rates.

RESULTS

There were no significant differences in demographic and clinical characteristics of both groups, such as age, body mass index (BMI), duration of infertility, causes of infertility, and basal hormone levels. Clinicals pregnancy rate, in the study group, 48% (265/552) and in the control group, 50.8% (405/797) were similar in both groups. When the implantation rate and miscarriage rate were examined, both groups were found to be similar.

CONCLUSION

It was found that 360° rotation while pulling catheter during embryo transfer had no effect on pregnancy and clinical pregnancy.

Natural vs. programmed cycles for frozen embryo transfer: study protocol for an investigator-initiated, randomized, controlled, multicenter clinical trial

Background

Randomized trials of assisted reproductive technology (ART) have been designed for outcomes of clinical pregnancy or live birth and have not been powered for obstetric outcomes such as preeclampsia, critical for maternal and fetal health. ART increasingly involves frozen embryo transfer (FET). Although there are advantages of FET, multiple studies have shown that risk of preeclampsia is increased with FET compared with fresh embryo transfer, and the reason for this difference is not clear. NatPro will compare the proportion of preeclampsia between two commonly used protocols for FET,modified natural and programmed cycle.

Methods

In this two-arm, parallel-group, multi-center randomized trial, NatPro will randomize 788 women to either modified natural or programmed FET and follow them for up to three FET cycles. Primary outcome will be the proportion of preeclampsia in women with a viable pregnancy assigned to a modified natural cycle FET (corpus luteum present) protocol compared to the proportion of preeclampsia in pregnant women assigned to a programmed FET (corpus luteum absent) protocol. Secondary outcomes will compare the proportion of live births and the proportion of preeclampsia with severe features between the protocols.

Conclusion

This study has a potential significant impact on millions of women who pursue ART to build their families. NatPro is designed to provide clinically relevant guidance to inform patients and clinicians regarding maternal risk with programmed and modified natural cycle FET protocols. This study will also provide accurate point estimates regarding the likelihood of live birth with programmed and modified natural cycle FET.

Trial registration

ClinicalTrials.govNCT04551807. Registered on September 16, 2020

Supplementary Information

The online version contains supplementary material available at 10.1186/s13063-021-05637-3.

One step further: randomised single-centre trial comparing the direct and afterload techniques of embryo transfer

STUDY QUESTION

What are the differences in ease of use between two different embryo transfer (ET) techniques: the preload direct approach and the afterload approach.

SUMMARY ANSWER

The afterload technique seems to reduce the rate of difficult ETs.

WHAT IS KNOWN ALREADY

Numerous published trials now document that the ET procedure has an impact on pregnancy and delivery rates after IVF. Difficult transfers should be avoided, as they reduce implantation and pregnancy rates. Preload direct ETs with soft catheters under ultrasound guidance is currently considered the best procedure. However, when using soft catheters, it is not known which technique is preferable or which one should be implemented to reduce the operator factor.

STUDY DESIGN, SIZE, DURATION

This prospective randomised unblinded controlled clinical trial, included 352 ultrasound-guided ETs assigned to either direct ET or afterload ET, between September 2017 and March 2019. The sample size was calculated based on the historical rate of difficult ETs encountered between 2014 and 2015 with a direct ET procedure.

PARTICIPANTS/MATERIALS, SETTING, METHODS

The inclusion criteria were women 18-38 years old, with BMI between 18 and 28, receiving a single-thawed blastocyst transfer. The exclusion criteria were use of testicular sperm and preimplantation genetic testing (PGT) cycles. The primary outcome was the rate of difficult or suboptimal transfers defined as: advancement of the outer sheath (specific for the direct transfer), multiple attempts, use of force, required manipulation, use of a stylet or tenaculum, dilatation, or use of a different catheter. The secondary outcome was clinical pregnancy rate.

MAIN RESULTS AND THE ROLE OF CHANCE

A total of 352 frozen ETs were randomised, with 176 patients in each group. The two arms were homogeneous for female and male age, female BMI, duration of infertility, secondary infertility, previous deliveries or miscarriages, myomas, previous surgery to the uterine cavity, cycle day at ovulation trigger, freeze all cycles, first transfers, indication for treatment, endometrial preparation protocol and duration, endometrial thickness, and blastocyst grade at vitrification. Across the entire population, 85 (24.1%) ETs were defined as difficult. The rate of difficult transfers was significantly higher in the direct ET group than in the afterload group: 68 (38.6%) versus 17 (9.7%), respectively (OR 0.17, 95% CI 0.09-0.30, P < 0.001). The mean percentage in the rate of difficult transfers per operator was 22.5% (SD ± 14.5%), of which 36.1% (SD ± 23.4%) were in the direct group compared with 8.6% (± 8.2%) in the afterload group (P < 0.001). The difficult transfer rate among operators varied from 0 to 43.8% (0-77.8% in the direct group and 0 to 25.0% in the afterload group). The clinical pregnancy rates (42.0% vs 48.3%, P = 0.239 in the direct and afterload groups, respectively) were not significantly different between the groups.

LIMITATIONS, REASONS FOR CAUTION

There were 18 experienced operators who participated in the trial. Conclusions about the pregnancy rate should not be generalised, since the sample analysis was not performed on this outcome and, although clinically relevant, the difference was not significantly different.

WIDER IMPLICATIONS OF THE FINDINGS

The rate of difficult transfers was significantly higher in the direct ET group compared with the afterload ET group, although a wide variation was observed among operators. Further studies regarding the association between transfer technique and ART outcomes are required.

STUDY FUNDING/COMPETING INTEREST(S)

No specific funding was sought and there are no competing interests.

TRIAL REGISTRATION NUMBER

NCT03161119.

TRIAL REGISTRATION DATE

5 April 2017.

DATE OF FIRST PATIENT'S ENROLMENT

26 September 2017.

Evaluation of a strategy for difficult embryo transfers from a prospective series of 2,046 transfers

Objective

To evaluate an embryo transfer strategy for difficult transfers (DiTs).

Design

Prospective, nonrandomized, observational, cohort study

Setting

A hospital fertility center in France.

Patient(s)

Data were collected on all embryo transfers conducted using the strategy between February 2014 and February 2020.

Intervention(s)

Anatomical characteristics that could cause DiT were identified by transvaginal ultrasound and the catheter was adapted accordingly. Transfer was guided by transvaginal ultrasound. After passage through the cervix, a rest period was introduced to allow any contractions to stop before embryo deposition in the uterus.

Main Outcome Measure(s)

The primary criterion was the percentage of pregnancies per transfer (P/T) after an easy transfer (EaT) or a DiT. The secondary criteria included the anatomical causes of DiT and the patients’ levels of discomfort.

Result(s)

Of 2,046 transfers, 257 (12%) were DiTs: minor difficulties (n = 152; 7.4%), major difficulties (n = 96; 4.7%), very significant difficulties (n = 7; 0.3%), or impossible (n = 2; 0.1%). The most common causes of DiTs were endocervical crypts (54%), tortuous cervical canal (36%), and marked uterine anteversions (30%). Several causes were often responsible for DiTs. There was no statistically significant difference in the P/T between the EaTs (n = 1,789, 41%) and all degrees of DiT (n = 257, 37%). In addition, there was no statistically significant difference between the level of patient-reported discomfort in the EaT and DiT groups.

Conclusion(s)

This study demonstrated that an adapted embryo transfer strategy, monitored by transvaginal ultrasound, led to similar pregnancy rates regardless of whether the transfer was easy or difficult.

A New Concept in Minimally Invasive Embryo Transfer

Considerable variation in embryo transfer (ET) catheter types, diverging opinions on their quality and functionality, complications following the insertion of catheters, low efficiency of the application of ET methods in humans, and their widely varying efficiency in animals demonstrate the need to improve ET methods and to look for new types of catheters. Such an opportunity is offered by the introduction of catheters made of new-generation biomaterials. This study was aimed to introduce a new generation of biomaterials into reproductive biotechnology. New-generation materials were compared with materials that have been used for many years, and the functionality of newly produced catheters was compared in vivo. Five types of biomaterials were tested: polycaprolactone (PCL), dibutyryl chitin (DBC), polypropylene (PP), polyethylene (PE) and polylactide (PLA). The study was carried out in two stages. Firstly, the basic utility parameters such as geometric stability, surface structure and catheter resistance were evaluated. Subsequently, the biocompatibility of selected biomaterials in embryo cultures was examined, and the development potential of the obtained blastocysts was evaluated. In the second stage, in vivo with live animals, the biomaterials were tested for biocompatibility and the obtained catheters were examined for their ET functionality. Efficiency with the use of the newly produced catheters was determined, the quality of the blastocysts obtained after embryo culture in the uterus was assessed, and oviducts were subjected to histopathological examination after embryo transfer. Of the tested biomaterials, only polyethylene (PE) showed adequate biological and material properties and proved suitable for production of ET catheters.

Embryo location in the uterus during embryo transfer: An in vitro simulation

Objective

To evaluate the location of transferred embryos under various parameters during embryo transfer in in vitro fertilization (IVF) by applying an in vitro experimental model for embryo transfer (ET).

Methods

Mock ET simulations were conducted with a laboratory model of the uterine cavity. The transfer catheter was loaded with a sequence of air and liquid volumes, including development-arrested embryos donated by patients. The transfer procedure was recorded using a digital video camera. An orthogonal design, including three independent variables (uterine orientation, distance of the catheter tip to the fundus, and injection speed) and one dependent variable (final embryo position), was applied.

Results

The uterine cavity was divided into six regions. The distribution of the transferred matter within the uterine cavity varied according to the uterine orientation. Medium speed-injected embryos were mostly found in the static region while fast- and slow-speed injected embryos were mostly found in the fundal region and the cervical-left region, respectively. The possibility of embryo separation from the air bubble increased from 11.1% in slow injection cases to 29.6% and 48.1% in medium and fast injection cases, respectively.

Conclusion

The experimental model provides a new method for investigating ET procedures. Fast injection of embryos into a retroverted uterus may be more likely to result in embryo separation from the air bubble.

Which key performance indicators are optimal to assess clinical management of assisted reproduction cycles?

Like all industries, fertility clinics should identify and follow reference markers of its activity-key performance indicators (KPI)-to allow assisted reproductive technology outcomes to be monitored and compared. Clinical KPIs revolve around following set parameters of the patient population, procedures, and outcome data. Moreover, KPIs should also include identified protocols and standard operating procedures followed in daily practice and should keep track of multiple pregnancy rates, a ruthless confounder of assisted reproductive technology outcomes.

Comparison between embryos transferred with self-spent and fresh medium on reproductive outcomes: a prospective randomized trial

As the final and critical step in in vitro fertilization (IVF), embryo transfer has always received much attention and deserves continuous optimization. In the present study, to explore the role of autocrine factors in embryo self-spent culture media, we prospectively compared embryo transfer with self-spent culture medium and fresh medium on clinical pregnancy outcomes. A total of 318 fresh IVF/intracytoplasmic sperm injection (ICSI) cycles were randomly allocated into two subgroups based on their transfer media (using a self-spent culture medium or new pre-equilibrated culture media), and the clinical outcomes were compared between groups. The implantation rates, clinical pregnancy rates and live birth rates for transfer using self-spent medium instead of new pre-equilibrated culture medium were slightly improved without statistical significance. Interestingly, however, biochemical pregnancy rate was found to be significantly decreased after transfer using self-spent medium for Day 3 embryos compared with new pre-equilibrated culture media. In short, embryo transfer with self-spent culture medium has shown some advantages, and large sample size studies are still needed to confirm these observations.

ABBREVIATIONS

ART: assisted reproductive technologies; ICSI: intracytoplasmic sperm injection; IVF: in vitro fertilization; ET: embryo transfer.

Estimation of embryo transfer media viscosity and consideration of its effect on media and uterine fluid interactions

RESEARCH QUESTION

What are the viscosities of media used for human embryo transfer and what is the possible effect of viscosity as it relates to interactions between transfer media and uterine fluid.

DESIGN

Chamber slide filling times, in seconds, were used to calculate viscosity for each commercial and in-house modified medium, with 12 or 24 replicates per medium under standard operating procedure temperature and gas equilibration conditions used for embryo transfer. Means, standard deviations and coefficients of variation were calculated, and each viscosity was estimated using a regression equation; viscosities for each medium were presented for comparative purposes.

RESULTS

Complete culture media (G1-Plus, G2-Plus, G-TL, 1-Step, Global Total, Global Total HEPES, and Sperm Wash Medium) had viscosity estimates of 1.65 cP, 1.77 cP, 1.68 cP, 1.29cP, 1.18 cP, 1.15 cP, and 1.20 cP, respectively. Complete transfer media (EmbryoGlue, UTM), had viscosity estimates of 3.59 cP and 1.28 cP, respectively. Global HEPES medium with 10%, 20%, 30%, and 50% synthetic serum substitute (SSS) volume per volume had viscosity estimates 1.16 cP, 1.23 cP, 1.25 cP, and 1.34 cP, respectively. For reference, water had a viscosity estimate of 1.06 cP.

CONCLUSIONS

A relatively narrow distribution of viscosities was observed across several transfer media despite the various commercial or in-house modifications. These data demonstrate the vast difference between viscosities of embryo transfer media and the assumed viscosity of uterine fluid (1000 cP). Contemporary embryo transfer media may be well-suited for IVF, but evaluation of all variables, e.g. media viscosity in the context of embryo transfer, adds to the knowledge base that should be available to practitioners.

Three-dimensionally-printed models in reproductive surgery: systematic review and clinical applications

INTRODUCTION

3D printing has wide application in medicine while it provides customizability and precision for anatomical model development. Our aims were to perform a systematic review and to explore the use of 3D printing applications on human reproduction and reproductive surgery.

EVIDENCE ACQUISITION

We have performed a systematic review in PubMed database to assess previous publications within 3D printing in human reproduction and gynecology. We have developed 3D models according to patients' magnetic resonance images (MRI). MRI were transformed into DICOM images that originated our 3D virtual models and PolyJet technology was applied for the printing process. We included two infertile patients in reproductive age with surgical indication for hysteroscopy septoplasty and myomectomy.

EVIDENCE SYNTHESIS

Of 1965 studies searched, we excluded 1934 publications based on their titles. Abstracts of 31 remained studies were read, and 24 studies were selected for full-text analysis. We included 11 studies for the systematic review, based on our eligibility criteria. We have designed four 3D models (uterus, ovaries, uterine cervix and uterus with fibroids) that provided enriched information to improve pre-surgical planning, medical training, fertility-sparing surgery, patient comprehension of surgical procedures and assisted reproduction applications.

CONCLUSIONS

3D models for human reproduction are feasible. They might improve assisted reproductive techniques, help in pre-surgical planning for reproductive surgeries, and provide accurate measures of ovarian reserve. Besides, we see future applications in endometrioma research and in the fabrication of devices, such as embryo transfer catheter and a 3D printed embryo.

[Impact of air quality on practices and results in the IVF laboratory]

The concept of Air Quality often refers to particulate and microbiological contamination of ambiant air. European Directive 2006/86/CE encompass the IVF process and specify a class A air quality for manipulation of tissue and cells, in a class D environment (A over D rule). Recognizing the paramount importance of ensuring the highest microbiological and particulate safety in the IVF laboratory, it is equally important to take into account practicability issues and the financial burden of these recommendations, as well as the utter need to protect gametes and embryo viability during their IVF journey. The usefulness of such stringent recommendations may also be questionned given the absence of published cases of airborne contaminations and related patients infections after embryo transfer. The European directive stems from pharmaceutical standards and were not specifically designed for human IVF. Gametes and embryos are indeed extremely sensitive to physical and chemical stress and require strict temperature, osmolarity and pH control, as well as an absence of chemical contamination during manipulation and culture. These conditions are hardly obtained when using laminar flow hoods. Following concerns raised by many experts in the field, exceptions to the A over D rule were added in the 2006/86/CE Directives. This narrative review discusses all these aspects in a critical way and compare scientific and legal requirements applying to IVF practices in different regions of the world.

Ideal embryo transfer position and endometrial thickness in IVF embryo transfer treatment

OBJECTIVE

To establish an ideal transfer strategy by investigating the relationships among embryo transfer (ET) depth, endometrial thickness, and subsequent in vitro fertilization treatment clinical pregnancy outcomes.

METHODS

In the present retrospective analysis, data from in vitro fertilization-ET treatment cycles conducted at a fertility center in Shanghai, China, between October 2014 and March 2015 were analyzed. Women were divided into groups 1-4 according to transfer depth (<10; 10-15, 15-20, and >20 mm, respectively), as measured by air bubbles. Additionally, 391 women were divided into groups A-C according to endometrial thickness (<7, 1-12, and >12 mm, respectively). Clinical pregnancy outcomes were assessed by group.

RESULTS

Data from 501 cycles were included. Clinical pregnancy and live delivery rates were significantly higher in group 2 (P=0.009 and P=0.002, respectively) and group 3 (P=0.008 and P=0.001, respectively) than in group 4. Among the 394 patients with endometrial thickness data available, clinical pregnancy and live delivery rates were higher in group B (P=0.028 and P=0.015, respectively) and group (P=0.013 and P=0.013, respectively) than in group A.

CONCLUSION

Correct transfer depth and endometrial thickness can increase the rates of clinical pregnancy, implantation, and live delivery. Placing the embryos at 10-20 mm from the fundus and at an endometrial thickness of more than 7 mm is recommended for optimal clinical pregnancy outcomes.

COMFFETI, Combined Fresh and Frozen Embryo Transfers per Individual: A New Index of Quality Control for The Performance of emberyologic Labs in The Emerging Era of Segmentation of Cycle and Freeze-All Strategy

The efficacy of in vitro fertilization (IVF) for treating human infertility has only one final efficacy index and that is the achievement of a delivery. However, with the evolution of the freeze-all strategy, a new problem is arising for evaluating the performance of an embryological team. The aim of the study was to present a new representative index, combining fresh and frozen embryo transfer success rates. In this opinion article, apart from the effectiveness of managing fresh gametes and embryos, we wish to evaluate the efficacy of the processes of both freezing and thawing of the produced embryos. The reporting of pregnancy rates of an IVF unit in the past was primarily laying in the fresh embryo transfer (ET) pregnancy rates. Now with the most frequent utilization of freeze-all strategy, it does not seem logical to report only on poor prognosis patients as all the good cases are postponed for thawed cycles. Ongoing implementation of the freeze-all strategy has indicated the need to establish a new representative index that may combine the success of both fresh and frozen cycles performed in the same woman; an index that may not be biased by the policy of an IVF center towards or against the freeze-all strategy. This newly proposed index, which is referred to as COMFFETI (Combined Fresh & Frozen Embryo Transfers per Individual), describes the optimal way to report final reproductive outcomes in the present opinion article.

Do trained reproductive endocrinologists perform better than their trainees? Comparing clinical pregnancy rates and live birth rates after transfer of single fresh blastocysts

PURPOSE

To compare clinical pregnancy rates and live birth rates of single blastocyst transfers performed by attending physicians or fellows in reproductive endocrinology and infertility program.

METHODS

Retrospective study in an academic reproductive center. We evaluated 932 fresh single blastocyst transfer cycles performed by fellows in training (389 embryo transfers) and by attending physicians (543 embryo transfers).

RESULTS

There were no differences in the baseline characteristics and IVF cycle parameters between patients who had transfers performed by fellows or attending physicians. Transfers performed by attending physicians or fellows resulted in similar CPR (46.5 vs. 42.9%, p = 0.28) and LBR (38.3 vs. 34.2%, p = 0.11). Multivariate logistic regression analysis showed that even after adjusting for possible confounders (age, gravity, parity, baseline FSH, antral follicle count, dose of gonadotropins, stimulation protocol, and quality of embryo transferred), CPR (OR 0.81, CI 0.62-1.07) and LBR (OR 0.79, CI 0.6-1.05) in the two groups were comparable.

CONCLUSION

Clinical pregnancy rate and live birth rate after embryo transfer performed by attending staffs or fellows are comparable. This finding reassures fellowship programs that allowing fellows to perform embryo transfers does not compromise the outcome.

Low versus high volume of culture medium during embryo transfer: a randomized clinical trial

PURPOSE

The aim of this prospective randomized control trial was to evaluate if the use of two different volumes (20-25 vs 40-45 μl) of media used for embryo transfer affects the clinical outcomes in fresh in vitro fertilization (IVF) cycles.

METHODS

In total, 236 patients were randomized in two groups, i.e., "low volume" group (n = 118) transferring the embryos with 20-25 μl of medium and "high volume" group (n = 118) transferring the embryos with 40-45 μl of medium. The clinical pregnancy, implantation, and ongoing pregnancy rates were compared between the two groups.

RESULTS

No statistically significant differences were observed in clinical pregnancy (46.8 vs 54.3%, p = 0.27), implantation (23.7 vs 27.8%, p = 0.30), and ongoing pregnancy (33.3 vs 40.0%, p = 0.31) rates between low and high volume group, respectively.

CONCLUSION

Higher volume of culture medium to load the embryo into the catheter during embryo transfer does not influence the clinical outcome in fresh IVF cycles.

TRIAL REGISTRATION NUMBER

NCT03350646.

Qualifying the difficulty of embryo transfer with a visual analogue scale and assessing its impact on IVF outcomes

The aim of this study was to determine whether a continuous visual analogue scale (VAS) is a reliable tool to grade embryo transfer (ET) difficulty when assessing IVF outcomes. No standardized grading system exists for reporting ET 'difficulty' which is typically recorded in descriptive terms. Clinicians performing 188 fresh single ETs between November 2014 and May 2016 also recorded a VAS score (0-100). Embryo transfers were stratified into three levels of ET 'difficulty': (A) 'easy' - no resistance; (B) 'medium' - resistance overcome by advancing the catheter's outer sheath; and (C) 'difficult' - a malleable stylet was required to overcome resistance; and these compared to the VAS scores. Clinical pregnancy and live birth rates were the primary outcomes. VAS scores were categorized into four incremental groupings according to the 25th, 50th and 75th percentiles (Groups 1-4) for analysis. No significant relationship (p > 0.05) was seen in clinical pregnancy or live birth rates in either the standard difficulty or the VAS groupings. The median VAS scores in Groups A-C increased as difficulty increased, but the interquartile ranges overlap with wide clinician variation, suggesting the VAS is not itself a reliable enough tool to record ET difficulty in isolation.

Evaluation of the cervix tissue homogeneity by ultrasound elastography in infertile women for the prediction of embryo transfer ease: a diagnostic accuracy study

BACKGROUND

Ultrasound elastography is a non-invasive medical imaging technique able to quantitatively characterize the stiffness of a given tissue. It has been shown to predict the risk for cervical insufficiency and preterm delivery, and to allow differentiation of malignancy from normal tissue. The present study sought to evaluate whether cervical tissue dishomogeneity, as assessed by cervical ultrasound elastography, may predict the embryo transfer (ET) ease in infertile women undergoing IVF/ICSI.

METHODS

We evaluated 154 infertile patients with no history of previous ET or intrauterine insemination. Cervical stiffness was evaluated in six regions of interest (ROI), compared two by two to obtain strain ratio (SR) values. Since a SR value of 1 was suggestive of tissue homogeneity, we computed 1-SR/SR-1 values to obtain a measure of the degree of cervical tissue dishomogeneity that we named "dishomogeneity index" (DI). Ultrasound-guided ET was performed by an expert operator blinded to the results of cervical elastography. The prediction ability of elastography on ET ease was evaluated by binary logistic regression, and the predictive accuracy of the independent variables was quantified with area under the curve (AUC) estimates derived from receiver operating characteristic (ROC) curve.

RESULTS

ET resulted to be easy in 99 out of 154 patients (64,2%), difficult in 54 patients (35%), and impossible in one. DI values in cervical medial lips region correctly classified 86.9% of patients, according to binary logistic regression, with a sensitivity of 81.4% and a specificity of 89,9%, positive likelihood ratio (LR) 8.07 and negative LR of 0.21. A DI cut-off value of 0.29 predicted a difficulty of ET with a sensitivity of 88,9% and a specificity of 85%.

CONCLUSIONS

Cervical ultrasound elastography, by allowing the identification of cervical tissue dishomogeneity, may be of help in predicting the ET ease in infertile women candidates to IVF/ICSI.

A family study of complex chromosome rearrangement involving chromosomes 1, 8, and 11 and its reproductive consequences

Complex chromosome translocations are structural chromosomal rearrangements involving three or more chromosomes and more than two breakpoints. A complex chromosome rearrangement was detected in a phenotypically normal female patient that was referred to the hospital for genetic counseling due to reproductive failure. A cytogenetic evaluation was performed, according to standard method of chromosomal analysis, using G-banding technique. The patient's karyotype showed a balanced complex chromosome rearrangement (BCCR) involving chromosomes 1, 8, and 11 with three breakpoints 1p31, 8q13, and 11q23. The karyotype designed according to ISCN (2013), is 46,XX,t(1;8;11)(p31;q13;q23) (8qter→8q13::1p31→1qter;8pter→8q13::11q23→11qter;11pter→11q23::1p31→1pter). Additionally, the proband's mother and brother were tested, resulting in the same exact translocation. In this study, we describe all possible meiotic segregations regarding this translocation, as well as the clinical phenotypes which could arise, if unbalanced products of conception survive. This is a rare case of familial complex chromosome rearrangement, giving a view for its reproductive consequences.

Transvaginal ultrasound-guided embryo transfer in IVF

OBJECTIVES

To determine whether transvaginal ultrasound-guided embryo transfer is a technique that can be used routinely, whether it improves IVF outcomes and whether it makes difficult transfers easier and more successful.

MATERIAL AND METHOD

Non-randomized retrospective study conducted between 2012 and 2016 in the fertility center of the Diaconesses-Croix St-Simon hospital group. The outcomes of 3910 transfers, performed by 5 senior operators, under transabdominal ultrasound guidance are compared with those of 800 transfers, performed by 1 senior operator under transvaginal ultrasound guidance. The criteria studied are the feasibility of the technique and the percentage of pregnancies per transfer in the two populations described, as well as in the difficult and very difficult transfer populations.

RESULTS

All the transfers were feasible under transvaginal ultrasound guidance without the use of forceps or additional instruments. The percentage of pregnancies per transfer is significantly increased, when the transfer is performed under transvaginal ultrasound guidance compared with that performed under transabdominal ultrasound guidance, in the general population (38%, n=800 vs 30%, n=3910; P 0.0004) and in the reference population characterized by age <38 years and >6 oocytes collected per puncture (45%, n=490 vs 36%, n=1968; P 0.002). The percentage of pregnancies per transfer (P/T) is not significantly different in the populations of easy transfers (n 695, 38% P/T), difficult transfers (n 58, 46% P/T; P=ns) and very difficult transfers (n 47, 34% P/T; P=ns).

CONCLUSIONS

Embryo transfer is a key stage in IVF, in which the quality of performance determines the outcome. In this study, transvaginal ultrasound guidance of the transfer, which is the reference procedure in gynaecological imaging, significantly increases the percentage of pregnancies per transfer, both in the general population and in the reference population, compared with transfers performed under transabdominal ultrasound guidance. Transvaginal ultrasound facilitates the performance of difficult transfers and in particular achieves outcomes in these situations that are not significantly different from those of easy transfers. Visual monitoring of transcervical passage, which is rendered more precise and less traumatic and precision of embryo deposition are the factors that probably account for the improvement in outcomes.

Intrauterine administration of hCG immediately after oocyte retrieval and the outcome of ICSI: a randomized controlled trial

STUDY QUESTION

Does the intrauterine administration of hCG immediately after oocyte retrieval in antagonist cycles with ICSI and fresh embryo transfer (ET) influence the implantation rate or chemical and clinical pregnancy rates?

SUMMARY ANSWER

The intrauterine administration of hCG after oocyte retrieval increases the implantation rate and chemical and clinical pregnancy rates.

WHAT IS KNOWN ALREADY

Over half of IVF/ICSI cycles fail due to implantation failure. Intrauterine administration of hCG, a few minutes before ET, increased the implantation and pregnancy rates in most but not in all studies. The effect of intrauterine administration of hCG, after oocyte retrieval, has not yet been studied.

STUDY DESIGN, SIZE, DURATION

The study was a parallel, triple-blind randomized clinical trial (RCT) performed from September 2015 to February 2016, in a university hospital. We recruited women undergoing antagonist ovarian stimulation, ICSI and ET. For an effect size of 0.2, power of 80% at a significance level of 0.05, we needed 150 participants. Accounting for a 7% dropout rate, a total of 160 women was considered appropriate. A computer-generated randomization list with a block size of 4, with 1:1 allocation was used. The treatment allocation was placed in a sealed, opaque, envelope and picked up consecutively. Immediately after oocyte retrieval, patients in the intervention and control groups were treated with intrauterine injection of hCG and saline, respectively. Participants underwent ET on Day 3. A beta-hCG test was done at 2 weeks. If positive, three transvaginal-ultrasonographies (TVSs) were done at 3, 4 and 10 weeks after ET. The participants were called up thereafter and questioned about the continuity of their pregnancy.

PARTICIPANTS/MATERIALS, SETTING, METHOD

Of 1990 women attending the infertility clinic of our university hospital, 508 were IVF/ICSI candidates during the study period, and 245 of the patients on an antagonist cycle met the criteria to be invited into our trial. Inclusion criteria were normal ovarian reserve, age ≤41, undergoing ICSI, and fresh ET and normal TSH and prolactin. Uncontrolled chronic disease, severe hydrosalpinx, severe endometriosis, morphologic embryo deficiencies, non-obstructive azospermia and high risk of severe ovarian hyperstimulation syndrome were criteria for exclusion. After taking an informed consent, a total of 158 participants were recruited, of which 80 were randomly allocated to receive intrauterine 500 IU hCG in up to 0.5 ml normal saline and 78 to receive intrauterine 0.5 ml normal saline immediately after oocyte retrieval, during general anaesthesia. ICSI was performed conventionally. The 4-8 cell embryos were transferred on the third day after oocyte retrieval. Implantation rate, chemical and clinical pregnancy rates were analysed and compared between the two groups.

MAIN RESULTS AND THE ROLE OF CHANCE

Patients' demographic and baseline characteristics were comparable. The clinical results showed statistically significant differences between the two groups regarding the biochemical pregnancy rate (59.2 versus 31.3%; P = 0.001; odds ratio (OR) = 1.88; 95% CI, 1.26-2.82; risk difference (RD) = 27.8; 95% CI, 11.2-42.3), implantation rate (37 versus 17%; P = 0.012; OR = 2.29; 95% CI, 1.02-5.14; RD = 20.2; 95% CI, 5.4-33.8), clinical pregnancy rate (50.7 versus 16.4%; P < 0.001; OR = 3.08; 95% CI, 1.71-5.55; RD = 34.3; 95% CI, 18.7-47.6) and ongoing pregnancy rate (40.1 versus 13.4%; P = 0.001; OR = 3.04; 95% CI, 1.55-5.93; RD = 27.4; 95% CI, 12.7-40.6). The abortion and ectopic pregnancy rates were not statistically different between the two groups.

LIMITATIONS, REASONS FOR CAUTION

The insertion of an intrauterine insemination catheter and the injection of a small amount of saline into the uterine cavity (without hCG) may also have some impact on implantation. This effect could be studied by comparing this intervention with another study group without any intrauterine injection.There are no specific side effects mentioned in the literature for the intrauterine administration of hCG, neither were any observed in our study, but it is best to be cautious about probable side effects, because this type of intervention is relatively new and experimental, and deserves more studies before being entered into routine clinical practice.

WIDER IMPLICATIONS OF THE FINDINGS

Intrauterine administration of hCG immediately after oocyte pick up increases its effectiveness; however, further investigations are required before this procedure can be recommended for clinical practice.

STUDY FUNDING/COMPETING INTERESTS

This study was supported by the Women's Health Research Center, Tabriz University of Medical Sciences, Iran. No external funds were used. The authors have no conflicts of interest to declare.

TRIAL REGISTRATION NUMBER

IRCT201206165485N4.

TRIAL REGISTRATION DATE

2 September 2015.

DATE OF FIRST PATIENT'S ENROLMENT

2 September 2015.