Impact of EmbryoGlue as the embryo transfer medium

The functional roles of protein glycosylation in human maternal-fetal crosstalk

BACKGROUND

The establishment of maternal-fetal crosstalk is vital to a successful pregnancy. Glycosylation is a post-translational modification in which glycans (monosaccharide chains) are attached to an organic molecule. Glycans are involved in many physiological and pathological processes. Human endometrial epithelium, endometrial gland secretions, decidual immune cells, and trophoblasts are highly enriched with glycoconjugates and glycan-binding molecules important for a healthy pregnancy. Aberrant glycosylation in the placenta and uterus has been linked to repeated implantation failure and various pregnancy complications, but there is no recent review summarizing the functional roles of glycosylation at the maternal-fetal interface and their associations with pathological processes.

OBJECTIVE AND RATIONALE

This review aims to summarize recent findings on glycosylation, glycosyltransferases, and glycan-binding receptors at the maternal-fetal interface, and their involvement in regulating the biology and pathological conditions associated with endometrial receptivity, placentation and maternal-fetal immunotolerance. Current knowledge limitations and future insights into the study of glycobiology in reproduction are discussed.

SEARCH METHODS

A comprehensive PubMed search was conducted using the following keywords: glycosylation, glycosyltransferases, glycan-binding proteins, endometrium, trophoblasts, maternal-fetal immunotolerance, siglec, selectin, galectin, repeated implantation failure, early pregnancy loss, recurrent pregnancy loss, preeclampsia, and fetal growth restriction. Relevant reports published between 1980 and 2023 and studies related to these reports were retrieved and reviewed. Only publications written in English were included.

OUTCOMES

The application of ultrasensitive mass spectrometry tools and lectin-based glycan profiling has enabled characterization of glycans present at the maternal-fetal interface and in maternal serum. The endometrial luminal epithelium is covered with highly glycosylated mucin that regulates blastocyst adhesion during implantation. In the placenta, fucose and sialic acid residues are abundantly presented on the villous membrane and are essential for proper placentation and establishment of maternal-fetal immunotolerance. Glycan-binding receptors, including selectins, sialic-acid-binding immunoglobulin-like lectins (siglecs) and galectins, also modulate implantation, trophoblast functions and maternal-fetal immunotolerance. Aberrant glycosylation is associated with repeated implantation failure, early pregnancy loss and various pregnancy complications. The current limitation in the field is that most glycobiological research relies on association studies, with few studies revealing the specific functions of glycans. Technological advancements in analytic, synthetic and functional glycobiology have laid the groundwork for further exploration of glycans in reproductive biology under both physiological and pathological conditions.

WIDER IMPLICATIONS

A deep understanding of the functions of glycan structures would provide insights into the molecular mechanisms underlying their involvement in the physiological and pathological regulation of early pregnancy. Glycans may also potentially serve as novel early predictive markers and therapeutic targets for repeated implantation failure, pregnancy loss, and other pregnancy complications.

The efficacy of add-ons: selected IVF "add-on" procedures and future directions

Since the advent of ART, technology has continuously evolved to improve embryology and pregnancy outcomes. However, not all technologies that are integrated into practice have convincing evidence of clinical effectiveness, and they often increase the financial burden of fertility care. We discuss here a selection of commonly utilized IVF "add-ons" and discuss the existing evidence for their utility. The procedures included in this review are time-lapse imaging of embryos, assisted hatching, EmbryoGlue, sperm DNA testing, egg activation with calcium ionophore, endometrial receptivity array, and physiological intracytoplasmic sperm injection (PICSI). While there is rather limited supporting evidence for nearly all IVF add-ons that we reviewed, there is strong demand from patients, physicians, and the biotechnology industry to continue further research and development in this arena. We propose that all add-on procedures should provide true efficacy for the patient, and reproductive endocrinologists should inform patients of the costs and benefits of utilizing various technologies before they undergo treatment. In the future, add-ons that show clear evidence of efficacy and justifiable cost should be incorporated into routine practice, while others that do not meet these criteria should be phased out entirely.

A fine tuning of embryo loading technique by eliminating the air bubble in the outer sheath of embryo catheter among women undergoing IVF treatment

OBJECTIVES

The role of air bubbles in bracketing the embryo-containing medium in inner catheter during embryo transfer (ET) has already been established. However, the role of air bubbles in outer catheter (OC) during implantation is yet to be determined. This study aimed to compare the implantation rates between women who have undergone ET with or without ASP (Vitrolife^®; Sweden), a medium use for oocyte retrieval and rinsing in OC embryo catheter. The purpose of introducing the ASP medium to the OC was to eliminate air bubbles in that space during implantation.

METHODS

A total of 312 women were randomly divided into two groups with 156 participants each group. In Group A, ASP medium was used during ET, whereas in Group B, no ASP medium was utilized. Positive implantation was defined as serum beta-hCG level >5 mIU/mL taken on the 7th day following ET.

RESULTS

The average age of the majority of the participants was 30-39 years and had at least 4-5 years of subfertility. The unexplained subfertility was the prominent cause of ET failure in both groups. In most of the participants in both groups, ET was done using fresh embryo cycles with good to excellent embryo grades. After the ASP medium was manipulated in the OC in both groups, the positive implantation rate was not different in both groups (p>0.05).

CONCLUSIONS

The elimination of air bubbles in OC by using the ASP medium during ET did not confer an additional benefit nor exert a negative impact on implantation rate.

Clinical efficacy of hyaluronate-containing embryo transfer medium in IVF/ICSI treatment cycles: a cohort study

STUDY QUESTION

Does the duration of embryo exposure to hyaluronic acid (HA) enriched medium improve the rate of live birth events (LBEs)?

SUMMARY ANSWER

The use of embryo transfer (ET) medium rich in HA improves LBE (a singleton or twin live birth) regardless of the duration of exposure evaluated in this study, but does not alter gestation or birthweight (BW).

WHAT IS KNOWN ALREADY

HA-enriched medium is routinely used for ET in ART to facilitate implantation, despite inconclusive evidence on safety and efficacy.

STUDY DESIGN SIZE DURATION

A cohort study was performed evaluating clinical treatment outcomes before and after HA-enriched ET medium was introduced into routine clinical practice. In total, 3391 fresh ET procedures were performed using low HA and HA-rich medium in women undergoing publicly funded IVF/ICSI treatment cycles between May 2011 and April 2015 were included in this cohort study.

PARTICIPANTS/MATERIALS SETTING METHODS

A total of 1018 ET performed using low HA medium were compared with 1198, and 1175 ET following exposure to HA-rich medium for 2-4 h (long HA exposure) or for 10-30 min (short HA exposure), respectively. A multiple logistic regression analysis was used to compare clinical outcomes including BW, gestational age and sex ratios between groups, whilst adjusting for patient age, previous attempt, incubator type and the number of embryos transferred.

MAIN RESULTS AND THE ROLE OF CHANCE

The use of HA-rich medium for ET was positively and significantly associated with improved clinical pregnancy rate and LBE, for both exposure durations: long HA (odds ratio (OR) = 1.21, 95% CI: 0.99-1.48), short HA (OR = 1.32, 95% CI: 1.02-1.72) and pooled OR = 1.26, 95% CI: 1.03-1.54, relative to the use of low HA medium. A comparative analysis of the risks of early pregnancy loss following long HA exposure (OR = 0.76, 95% CI: 0.54-1.06), short HA exposure (OR = 0.84, 95% CI: 0.54-1.30) and late miscarriage (OR = 0.88, 95% CI: 0.51-1.53) (OR = 1.41, 95% CI 0.72-2.77), were lower and not statistically significant. Similarly, ordinary regression analysis of the differences in BW at both HA exposures; pooled OR = -0.9 (-117.1 to 115.3), and adjusted BW between both HA cohorts; pooled OR = -13.8 (-106.1 to 78.6) did not show any differences. However, a difference in gestational age (pooled OR -0.3 (-3.4 to 2.9)) and sex ratio (pooled OR 1.43 (0.95-2.15)) were observed but these were not statistically significant relative to low HA medium.

LIMITATIONS REASONS FOR CAUTION

The strength of a randomized treatment allocation was not available in this evaluation study, therefore effects of unmeasured or unknown confounding variables cannot be ruled out.

WIDER IMPLICATIONS OF THE FINDINGS

The result of this large cohort study strengthens the case for using HA-rich medium routinely at transfer, while adding the important clinical information that duration of exposure may not be critical. The composition and effects of commercial IVF culture media on success rate and safety remains a major controversy despite increasing calls for transparency and evidence-based practice in ART. Nonetheless, the lack of differences in BW and gestational age observed in this study were reassuring. However, an appraisal of clinical outcomes and appropriate research investigations are required for the continuous evaluation of efficacy and safety of HA.

STUDY FUNDING/COMPETING INTERESTS

T.A. is funded by a Clinical Doctoral Research Fellowship (CDRF) grant (reference: ICA-CDRF-2015-01-068) from the National Institute for Health Research (NIHR). The views expressed in this publication are those of the authors and not necessarily those of the NHS, the National Institute for Health Research or the Department of Health. The authors declare no conflict of interest.

Influence of EmbryoGlue® transfer medium on implantation of human embryos

Introduction: Thanks to ever-growing advances in medical science, couples who are in the in vitro fertilisation (IVF) now have more options than ever to encase their chances at a successful pregnancy. One of the options is the use of EmbryoGlue (EG), that creates a bridge between the embryo and the uterus and provides protection to the embryo itself during the transfer process. Aim of this study was to determine whether EG medium is of greater importance for embryo implantation than conventional medium in assisted reproductive technology and compare the rate of embryo implantation with EG and conventional medium in relation to the quality of the embryo, the age of the patients and tobacco smoking. Methods: The retrospective study included 50 patients who used EG medium in embryo transfer (ET) and 50 patients in the control group using conventional medium. All patients underwent ET after stimulation of the cycle according to a short protocol. ETs were done on Day 2, 3, or 5 in the blastocyst stage. Age and smoking status were recorded. Results: Out of a total of 100 patients, 42 patients had successful implantation and positive b-hCG 15 days after ET. In a control group 38 % had positive b-hCG and in the group of patients who used EG 46 %. A higher rate of embryo implantation success was observed on the second day of transfer in the group of patients using EG. In the EG group a significant increase in the embryo implantation rate was observed in patients older than 35. In tobacco smokers the implantation rate was higher if they used EG during ET. Conclusion: EG medium had a positive effect on the second day of ET, patients above the age of 35 and patients who were tobacco smokers.

Hyaluronic acid in embryo transfer media for assisted reproductive technologies

BACKGROUND

This is an update of a Cochrane Review first published in the Cochrane Library (2010, Issue 7). To increase the success rate of assisted reproductive technologies (ARTs), adherence compounds such as hyaluronic acid (HA) have been introduced into subfertility management. Adherence compounds are added to the embryo transfer medium to increase the likelihood of embryo implantation, with the potential for higher clinical pregnancy and live birth rates.

OBJECTIVES

To determine whether adding adherence compounds to embryo transfer media could improve pregnancy outcomes, including improving live birth and decreasing miscarriage, in women undergoing assisted reproduction.

SEARCH METHODS

We searched the Cochrane Gynaecology and Fertility Group Trials Register, CENTRAL, MEDLINE, Embase, and PsycINFO electronic databases on 7 January 2020 for randomised controlled trials that examined the effects of adherence compounds in embryo transfer media on pregnancy outcomes. Furthermore, we communicated with experts in the field, searched trials registries, checked reference lists of relevant studies, and conference abstracts were handsearched.

SELECTION CRITERIA

Only truly randomised controlled trials comparing embryo transfer media containing functional concentrations of adherence compounds to media with no or low adherence compound concentrations were included.

DATA COLLECTION AND ANALYSIS

Two review authors selected trials for inclusion according to the above criteria, after which the same two review authors independently extracted data for subsequent analysis. Statistical analysis was performed according to the guidelines developed by Cochrane. We combined data to calculate pooled risk ratios (RRs) and 95% confidence intervals (CIs). We assessed statistical heterogeneity using the I² statistic. We used GRADE methods to assess the overall quality of evidence for the main comparisons.

MAIN RESULTS

We analysed 26 studies with a total of 6704 participants. Overall, the certainty of evidence was low to moderate: the main limitations were imprecision and/or heterogeneity. Compared to embryos transferred in media containing no or low (0.125 mg/mL) HA, the addition of functional (0.5 mg/mL) HA concentrations to the transfer media probably increases the live birth rate (RR 1.21, 95% CI 1.1 to 1.31; 10 RCTs, N = 4066; I² = 33%; moderate-quality evidence). This suggests that if the chance of live birth following no HA addition in media is assumed to be 33%, the chance following HA addition would be between 37% and 44%. The addition of HA may slightly decrease miscarriage rates (RR 0.82, 95% CI 0.67 to 1.00; 7 RCTs, N = 3091; I² = 66%; low-quality evidence). Nevertheless, when only studies with low risk of bias were included in the analysis, there was no conclusive evidence of a difference in miscarriage rates (RR 0.96, 95% CI 0.75 to 1.23; N = 2219; I² = 36%). Adding HA to transfer media probably results in an increase in both clinical pregnancy (RR 1.16, 95% CI 1.09 to 1.23; 17 studies, N = 5247; I² = 40%; moderate-quality evidence) and multiple pregnancy rates (RR 1.45, 95% CI 1.24 to 1.70; 7 studies, N = 3337; I² = 36%; moderate-quality evidence). We are uncertain of the effect of HA added to transfer media on the rate of total adverse events (RR 0.86, 95% CI 0.40 to 1.84; 3 studies, N = 1487; I² = 0%; low-quality evidence).

AUTHORS' CONCLUSIONS

Moderate-quality evidence shows improved clinical pregnancy and live birth rates with the addition of HA as an adherence compound in embryo transfer media in ART. Low-quality evidence suggests that adding HA may slightly decrease miscarriage rates, but when only studies at low risk of bias were included in the analysis, the results were inconclusive. HA had no clear effect on the rate of total adverse events. The increase in multiple pregnancy rates may be due to combining an adherence compound and transferring more than one embryo. Further studies of adherence compounds with single embryo transfer need to be undertaken.

The impact of hyaluronan-enriched culture medium and intrauterine infusion of human chorionic gonadotropin on clinical outcomes in blastocyst transfer cycles

Over the last few decades, advances in ovarian hormonal stimulation, embryology laboratory technologies and embryo genetic testing, have significantly enhanced clinical outcomes in human assisted reproduction technologies (ART). However, embryo implantation remains a major bottleneck in achieving better pregnancy and live birth rates. Thus, there is growing interest in establishing new approaches to enhance implantation efficiency after embryo transfer. With advanced molecular techniques, many promising biomarkers associated with embryonic and endometrial changes occurring prior to and during embryo implantation have been identified. However, despite the progress in applying novel procedures into IVF practice, clinical evaluation of those biomarkers has so far reached modest predictive value for enhancing blastocyst developmental potential and endometrial receptivity. Therefore, other simpler strategies have also been introduced to increase the rates of successful clinical pregnancies and live births. One of these approaches is to investigate the impact of using embryo transfer medium containing high concentrations of an adherence compound, such as hyaluronic acid (HA), on IVF outcomes. Additionally, intrauterine infusion of a small volume of human chorionic gonadotropin (hCG) at the time of embryo transfer (ET) has also been proposed as a technique that might be advantageous for increasing the clinical outcomes, considering the fact that hCG plays a critical role in synchronizing endometrial and fetal development. However, the current findings from both interventions remain controversial, demonstrating a mixture of positive and indifferent results of these treatments in ART cycles. Further research will be crucial for a better understanding of the molecular mechanism of cross-talk between the blastocyst and the maternal endometrium during the optimal implantation period when using either hyaluronan-enriched medium or hCG infusion before embryo transfers. Therefore, this review aims to present existing literature related to both treatments, emphasizing their effects on blastocyst implantation.Abbreviations: ART: assisted reproduction technologies; HA: hyaluronic acid; hCG: human chorionic gonadotrophin; IVF: in vitro Fertilization; ET: embryo transfer; pH: hydrogen ions; CO2: Carbone dioxide; O2: Oxygen; PGT: pre-implantation genetic testing; FET: frozen embryo transfer; PCOS: Polycystic ovarian syndrome; DNA: deoxyribonucleic acid; miRNA: micro-ribonucleic acid; EVs: extracellular vesicles; ERA: endometrial receptivity array; CD44 and RHAMM: primary hyaluronan surface receptors; RCT: randomized clinical trials; LBR: life birth rate; CPR: clinical pregnancy rate; IR: implantation rate.

Regulation and roles of the hyaluronan system in mammalian reproduction

Hyaluronan (HA) is a non-sulphated glycosaminoglycan polymer naturally occurring in many tissues and fluids of mammals, including the reproductive system. Its biosynthesis by HA synthase (HAS1–3) and catabolism by hyaluronidases (HYALs) are affected by ovarian steroid hormones. Depending upon its molecular size, HA functions both as a structural component of tissues in the form of high-molecular-weight HA or as a signalling molecule in the form of small HA molecules or HA fragments with effects mediated through interaction with its specific cell-membrane receptors. HA is produced by oocytes and embryos and in various segments of the reproductive system. This review provides information about the expression and function of members of the HA system, including HAS, HYALs and HA receptors. We examine their role in various processes from folliculogenesis through oocyte maturation, fertilisation and early embryo development, to pregnancy and cervical dilation, as well as its application in assisted reproduction technologies. Particular emphasis has been placed upon the role of the HA system in pre-implantation embryo development and embryo implantation, for which we propose a hypothetical sequential model.

Influence of hyaluronan on endometrial receptivity and embryo attachment in sheep

An increasing number of reports suggests a role of hyaluronan (HA) in female reproduction and interest in its application in assisted reproduction is rising. However, there are contrasting data about the effectiveness of adding HA to the embryo-transfer medium on improving pregnancy rates. Using sheep as an experimental model, the studies reported here analysed the impact of HA infusion into the uterus on embryo attachment to uterine luminal epithelium (LE) and expression of selected markers of uterine receptivity. On Day 14 after natural mating (pre-attachment), uterine horns were infused with either (n = 4 each): PBS (control), HA (1 mg mL–1), HA + hyaluronidase 2 (Hyal2; 300 IU mL–1) or 4-methyl-umbelliferone (HA-synthesis inhibitor; 4MU, 1 mM). HA immunostaining on uterine sections collected on Day 17 was negative in the 4MU group and weak in the HA+Hyal2 group. In contrast to 4MU, which resulted in 100% attachment, HA infusion blocked embryo attachment in all treated animals. This was accompanied by the disappearance of mucin 1 and increased expression of osteopontin and CD44v6 in the LE of uteri with attached embryos. In conclusion, the presence of HA at the embryo–maternal interface during embryo implantation resulted in reduced endometrial receptivity and inhibited the interaction of trophoblasts with the LE, whereas clearance of HA favoured embryo attachment.

How do laboratory embryo transfer techniques affect IVF outcomes? A review of current literature

Over the last few years, many studies have focused on embryo selection methods, whereas little attention has been given to the standardization of the procedure of embryo transfer. In this review, several parameters of the embryo transfer procedure are examined, such as the: (i) culture medium volume and loading technique; (ii) syringe and catheters used for embryo transfer; (iii) viscosity and composition of the embryo transfer medium; (iv) environment of embryo culture; (v) timing of embryo transfer; (vi) and standardization of the embryo transfer techniques. The aim of this manuscript is to review these factors and compare the existing embryo transfer techniques and highlight the need for better embryo transfer standardization.

Role of Embryo Glue as a transfer medium in the outcome of fresh non-donor in-vitro fertilization cycles

BACKGROUND

EmbryoGlue is a hyaluronan-enriched embryo transfer (ET) medium which aids in implantation of embryos, hence, improves pregnancy rates in in-vitro fertilization-ET cycles (IVF-ET).

AIM

To evaluate the role of EmbryoGlue in improving implantation and pregnancy rates.

DESIGN AND SETTING

A prospective case-control study conducted at assisted reproductive center of a tertiary care hospital.

METHOD

In 42 women undergoing IVF, embryos were transferred into 50 μL of EmbryoGlue for 10 min prior to transfer inside uterine cavity. In the control group (n = 42), embryos were transferred to conventional blastocyst culture medium. Statistical analysis was performed using SPSS IBM version 19.0.

RESULTS

Clinical pregnancy rate in the study group was 7% higher than the control group. The difference, however, was not statistically significant. In addition, no improvement in implantation rates was observed in the study group. However, significant difference (P = 0.04) in clinical pregnancy rate was observed with the EmbryoGlue in patients with previous IVF failure. In the study group, 50% patients (6/12) with previous IVF failure had successful implantation, but in the control group none of the patients (0/11) with previous implantation failure could achieve pregnancy.

CONCLUSION

It is difficult to conclude a favourable role of EmbryoGlue in IVF-ET cycles with a good prognosis. However, in patients with recurrent implantation failure, it may be considered as a useful transfer medium.

The effect of embryo catheter loading technique on the live birth rate

Objective

Embryo loading (EL) is a major step in embryo transfer (ET) and affect on the success of in vitro fertilization (IVF). This study aimed to compare the effect of two different EL techniques on the rates of pregnancy and delivery in IVF/ET cycles.

Methods

207 fresh ET and 194 Frozen-thawed ET (FET) cycles were included in this retrospective study. Two groups (A and B) were defined based on the EL technique used. In group A, the entire catheter was flushed with Ham's F-10 medium. The embryos were then drawn into the catheter using one air bracket. In group B, 70 µL of air was aspirated into the syringe and the catheter was flushed using Ham's F10 medium. The medium, air, embryos, air, and finally another layer of medium were then sequentially drawn into the catheter. The main outcome measures were the pregnancy and delivery rates.

Results

The groups did not differ with respect to the etiology of infertility, the source of spermatozoa, the quality of the embryos, the type of EL catheter, and the ease of transfer. The pregnancy rate was similar between two groups. In fresh ET cycles, a higher delivery rate was observed in group B than it group A (78.1% vs. 60%, p=0.1). In FET cycles, the rate of delivery was significantly higher in group B than in group A to a nonsignificant extent (88.9% vs. 58.8%, p=0.06).

Conclusion

EL techniques did not have a significant impact on the delivery rate in either fresh or FET cycles.

Post-embryo transfer interventions for assisted reproduction technology cycles

BACKGROUND

In women undergoing in vitro fertilisation (IVF) and intracytoplasmic sperm injection (ICSI), embryos transferred into the uterine cavity can be expelled due to many factors including uterine peristalsis and contractions, low site of deposition and negative pressure generated when removing the transfer catheter. Techniques to reduce the risk of embryo loss following embryo transfer (ET) have been described but are not standard in all centres conducting ET.

OBJECTIVES

To evaluate the efficacy of interventions used to prevent post-transfer embryo expulsion in women undergoing IVF and ICSI.

SEARCH METHODS

We searched the Menstrual Disorders and Subfertility Group Specialised Register of controlled trials to June 2014 and PubMed, MEDLINE, EMBASE, CENTRAL, PsycINFO, CINAHL, World Health Organization ICTRP, and trial registers from inception to June 2014, with no language restrictions. Additionally, we handsearched reference lists of relevant articles, and ESHRE and ASRM conference abstracts.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) of interventions used to prevent post-transfer embryo expulsion in women undergoing IVF and ICSI. Two review authors independently screened titles and abstracts and reviewed the full-texts of all potentially eligible citations to determine whether they met our inclusion criteria. Disagreements were resolved by consensus.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted data and assessed the risk of bias of included trials using standardised, piloted data extraction forms. Data were extracted to allow intention-to-treat analyses. Disagreements were resolved by consensus. The overall quality of the evidence was rated using GRADE methods.

MAIN RESULTS

We included four RCTs (n = 1392 women) which administered the following interventions: bed rest (two trials), fibrin sealant (one trial), and mechanical closure of the cervix (one trial). Our primary outcome, live birth rate, was not reported in any of the included trials; nor were the data available from the corresponding authors. For the ongoing pregnancy rate, two trials comparing more bed rest with less bed rest showed no evidence of a difference between groups (odds ratio (OR) 0.88; 95% confidence interval (CI) 0.60 to 1.31, 542 women, I(2) = 0%, low quality evidence). Secondary outcomes were sporadically reported with the exception of the clinical pregnancy rate, which was reported in all of the included trials. There was no evidence of a difference in clinical pregnancy rate between more bed rest and less bed rest (OR 0.88; 95% CI 0.60 to 1.31, 542 women, I(2) = 0%, low quality evidence) or between fibrin sealant and usual care (OR 0.98; 95% CI 0.54 to 1.78, 211 women, very low quality evidence). However, mechanical closure of the cervix was associated with a higher clinical pregnancy rate than usual care (OR 1.92; 95% CI 1.40 to 2.63, very low quality evidence). The quality of the evidence was rated as low or very low for all outcomes. The main limitations were failure to report live births, imprecision and risk of bias. Overall, the risk of bias of the included trials was high. The use of a proper method of randomisation and allocation concealment was fairly well reported, while only one trial clearly reported blinding. There was no evidence that any of the interventions had an effect on adverse event rates but data were too few to reach any conclusions.

AUTHORS' CONCLUSIONS

There is insufficient evidence to support any specific length of time for women to remain recumbent, if at all, following embryo transfer, nor is there sufficient evidence to recommend the use of fibrin sealants added to the embryo transfer fluid. There is very limited evidence to support the use of mechanical pressure to close the cervical canal following embryo transfer. Further well-designed and powered studies are required to determine the true effectiveness and safety of these interventions.

Adherence compounds in embryo transfer media for assisted reproductive technologies

BACKGROUND

This is an update of a Cochrane review first published in The Cochrane Library (2010, Issue 7).To increase the success rate of assisted reproductive technologies (ART), adherence compounds such as hyaluronic acid (HA) and fibrin sealant have been introduced into subfertility management. Adherence compounds are added to the embryo transfer medium to increase the likelihood of embryo implantation, with the potential for higher clinical pregnancy and live birth rates.

OBJECTIVES

To determine whether embryo transfer media containing adherence compounds improved live birth and pregnancy rates in ART cycles.

SEARCH METHODS

The Menstrual Disorders and Subfertility Group Trials Register, the Cochrane Central Register of Controlled Trials (CENTRAL) and MEDLINE, EMBASE and PsycINFO electronic databases were searched (up to 13 November 2013) to look for publications that described randomised controlled trials on the addition of adherence compounds to embryo transfer media. Furthermore, reference lists of all obtained studies were checked, and conference abstracts were handsearched.

SELECTION CRITERIA

Only truly randomised controlled trials comparing embryo transfer media containing functional (e.g. 0.5 mg/ml HA) concentrations of adherence compounds versus transfer media containing low or no concentrations of adherence compounds were included. The adherence compounds that were identified for evaluation were HA and fibrin sealant.

DATA COLLECTION AND ANALYSIS

Two review authors selected trials for inclusion according to the above criteria, after which two review authors independently extracted the data for subsequent analysis. Statistical analysis was performed in accordance with the guidelines developed by The Cochrane Collaboration.

MAIN RESULTS

Seventeen studies with a total of 3898 participants were analysed. One studied fibrin sealant, and the other 16 studied HA. No evidence was found of a treatment effect of fibrin sealant as an adherence compound. For HA, evidence of a positive treatment effect was identified in the six trials that reported live birth rates (odds ratio (OR) 1.41, 95% confidence interval (CI) 1.17 to 1.69; six RCTs, N = 1950, I(2) = 0%, moderate-quality evidence). Furthermore, the 14 trials reporting clinical pregnancy rates showed evidence of treatment benefit when embryos were transferred in media containing functional concentrations of HA (OR 1.39, 95% CI 1.21 to 1.60; 14 RCTs, N = 3452, I(2) = 46%, moderate-quality evidence) as compared with low or no use of HA. The multiple pregnancy rate (OR 1.86, 95% CI 1.49 to 2.31; five RCTs, N = 1951, I(2) = 0%, moderate-quality evidence) was significantly increased in the high HA group, but no significant differences in adverse event rates were found (OR 0.74, 95% CI 0.49 to 1.12; four RCTs, N = 1525, I(2) = 0%, moderate-quality evidence).

AUTHORS' CONCLUSIONS

Evidence suggests improved clinical pregnancy and live birth rates with the use of functional concentrations of HA as an adherence compound in ART cycles. However, the evidence obtained is of moderate quality. The increase in multiple pregnancy rate may be the result of use of a combination of an adherence compound and a policy of transferring more than one embryo. Further studies of adherence compounds with single embryo transfer need to be undertaken.

Impact of different embryo loading techniques on pregnancy rates in in vitro fertlization/embryo transfer cycles

BACKGROUND

Embryo transfer (ET) technique is one of the important factors of in vitro fertlization success. Among the different steps in ET technique, less attention has been given to embryo loading (EL). The aim was to compare the impact of two different techniques of EL on pregnancy rate in IVF/ET cycles.

MATERIALS AND METHODS

In this retrospective study, 144 and 170 patients were placed in groups A and B, respectively. In Group A, the embryos were drawn directly into the ET catheter from culture microdrop under the oil. In Group B, the embryos were transferred from culture microdrop into G2 medium in center-well dish. Then, the embryos were drawn into the catheter and finally transferred into the uterus. Both groups were adjusted for other parameters based on the EL technique. The main outcome measure was pregnancy rate.

RESULTS

There were insignificant differences for etiology of infertility, source of sperm, type of stimulation protocol, percent of IVF or intracytoplasmic sperm injection type of ET catheter, cycles with good quality embryos and transferred embryos between two groups. The rate of both chemical and clinical pregnancy was higher in Group B compared to A, but the difference was insignificant (P = 0.09 and P = 0.1, respectively).

CONCLUSION

It seems that there is no difference in the outcome by loading the embryo from microdrop or center-well dish.

Adherence compounds in embryo transfer media for assisted reproductive technologies

BACKGROUND

In order to increase the success rate of assisted reproductive technologies (ART), adherence compounds such as hyaluronic acid and fibrin sealant have been introduced into subfertility management. Adherence compounds are added to the embryo transfer medium in order to increase the likelihood of embryo implantation, with the potential for higher clinical pregnancy and live birth rates.

OBJECTIVES

To determine whether embryo transfer media containing adherence compounds affect the live birth rate in ART compared to transfer media without adherence compounds.

SEARCH STRATEGY

The Menstrual Disorders and Subfertility Group Trials Register, Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, EMBASE and PsycINFO electronic databases were searched (to 26th May 2009) for publications which described randomised controlled trials of the addition of adherence compounds to embryo transfer media. Furthermore, reference lists of all obtained studies were checked and conference abstracts handsearched.

SELECTION CRITERIA

Only truly randomised controlled trials comparing embryo transfer media containing adherence compounds with transfer media without (or with lower doses of) adherence compounds were included. The adherence compounds that were evaluated were hyaluronic acid and fibrin sealant.

DATA COLLECTION AND ANALYSIS

One review author selected the trials for inclusion according to the above criteria, after which two authors independently extracted the data for subsequent analysis. The statistical analysis was performed in accordance with the guidelines developed by The Cochrane Collaboration.

MAIN RESULTS

Sixteen studies with a total of 3698 participants were analysed. One studied fibrin sealant, the other 15 studied hyaluronic acid. There was no evidence of a treatment effect of fibrin sealant as an adherence compound. For hyaluronic acid, there was no evidence of a treatment effect on live birth rate. Evidence of treatment effects could be found for the clinical pregnancy rate (OR 1.41, 95% CI 1.22 to 1.63; P < 0.00001) and the multiple pregnancy rate (OR 1.86, 95% CI 1.49 to 2.31; P < 0.00001), with higher rates in the hyaluronic acid groups. No evidence of treatment effect was found for the other outcomes.

AUTHORS' CONCLUSIONS

There is evidence of an improved clinical pregnancy rate with the use of adherence compounds in ART cycles but no evidence of an effect on live birth rate. The increase in multiple pregnancy rate may be the result of the use of a combination of an adherence compound and a policy of transferring more than one embryo. Further studies of adherence compounds with single embryo transfer need to be undertaken.

[Views of each member of an Assisted Reproductive Technologies centre on the embryo transfer procedure]

The embryo transfer (ET) is probably the key step of Assisted Reproductive Technologies (ART), end point of the collaboration of a multidisciplinary clinical team and an infertile couple. Thus, a perfect knowledge of available data regarding ET is required to optimize the results of ART. Indeed, numerous published studies demonstrate the impact of defined parameters onto the effectiveness of ET procedure. The aim of this study is to provide views of physicians dealing with ART, i.e. endocrinologist, ultrasound scan specialist, surgeon and biologist to put in perspective questions and answers about ET.