A review and meta-analysis of prospective trials comparing different catheters used for embryo transfer

Four-dimensional ultrasound guided embryo transfers improve live birth rates when compared to the clinical touch technique: a randomised controlled trial

Most aspects of in-vitro fertilisation (IVF) have changed dramatically since introduction, but embryo transfer (ET) technique remains largely unaltered. We aimed to determine whether four-dimensional ultrasound guided embryo transfers (4D UGET) could improve pregnancy rates when compared with clinical touch technique (CTT). This was a single centre open labelled randomised controlled trial in a tertiary fertility centre in the UK. 320 women were randomised on the day of single ET. The primary outcome was clinical pregnancy rate (CPR), secondary outcomes included live birth rate (LBR), biochemical pregnancy rate (BPR), miscarriage, pregnancy of unknown location (PUL) and ectopic pregnancy. 4D-UGET resulted in significantly higher CPR [50% vs 36% p = 0.02, OR 1.78 (1.12-2.84)] and LBR [41% vs 28%, p = 0.02, OR 1.77 (1.09-2.87)] when compared to CTT technique. Miscarriage (p = 0.49), PUL (p = 0.14) and ectopic pregnancy (p = 0.96) were similar between the two groups. LBR, from this trial, are significantly higher than the current UK average (41% vs 24%). 4D UGET allows for superior imaging of the uterine cavity, whilst tailoring the embryo deposition point specifically to the patient. Further RCTs are required to determine if these results can be replicated in other units and whether 4D UGET is superior to 2D UGET.

Embryo transfer success: It is in our hands

Embryo transfer (ET) is considered as a critical step in the process of in vitro fertilization. Interestingly, studies have consistently shown significant outcome differences between physicians. Although the outcome of ET is not related to the physician's experience and specifically not different between fellows and attending physicians, certain techniques have been found to affect the success rate. This review summarizes the existing evidence regarding the impact of the individual physician performing ET and the techniques used.

Optimizing embryological aspects of oocyte retrieval, oocyte denudation, and embryo loading for transfer: a state of the art review

Oocyte retrieval, oocyte denudation, and embryo transfer are crucial processes during assisted reproduction (ART). Air quality in the ART laboratory, temperature, pH of the media used and the time interval between oocyte retrieval and insemination are all critical factors. Anesthesia is required for oocyte retrieval, however evidence regarding the potential impact of different methods (general anesthesia, conscious sedation, and local anesthesia) on the clinical outcomes is unclear. The optimal timing of oocyte denudation following retrieval has not been established. Regarding the mechanical denudation process, there is a lack of evidence to demonstrate the safest minimum inner diameter of denuding pipettes used to complete the removal of granulosa cells surrounding the oocytes. During embryo transfer, many clinics worldwide flush the catheter before embryo loading, in an attempt to potentially rinse off any toxic agents; however, there is insufficient evidence to show that flushing the embryo transfer catheter before loading increases the success of ART outcome. Considering the serious gaps in knowledge in ART practice, the aim of this review is to provide an updated overview of the current knowledge regarding the various steps and techniques involved in oocyte retrieval, oocyte denudation, and embryo loading for transfer.

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.

The human factor: does the operator performing the embryo transfer significantly impact the cycle outcome?

STUDY QUESTION

Is Ongoing Pregnancy Rate (OPR) operator-dependent, and can experience improve embryo transfer efficiency?

SUMMARY ANSWER

OPR is influenced by the operators who perform the embryo transfer (ET), and experience does not assure proficiency for everyone.

WHAT IS KNOWN ALREADY

ET remains the critical step in assisted reproduction. Although many other factors such as embryo quality and uterine receptivity impact embryo implantation, the proper ET technique is clearly an operator-dependent variable and as such it should be objectively standardized.

STUDY DESIGN, SIZE, DURATION

Retrospective comparative analysis including all fresh ETs performed between January 1996 and December 2016 at the Humanitas Fertility Center after IVF—ICSI cycles.

PARTICIPANTS/MATERIALS, SETTING, METHODS

IVF/ICSI fresh ETs performed by 32 operators, 19 824 cycles in all, were analyzed. All transfers consisting of freehand insertion of a preloaded soft catheter into the uterine cavity under transabdominal ultrasound guidance were considered. Two different statistical analyses were performed. First, a logistic regression model with a random intercept for the operator was used to estimate the heterogeneity of the rate of success among operators, accounting for woman age, FSH, number of oocytes retrieved, fertilization rate, year of the procedure, number and stage of transferred embryos and operator’s experience. Second, the relationship between experience and pregnancy rate was estimated separately for each operator by logistic regression, and operator-specific results were combined and compared in a random-effects meta-analysis. In both analyses, the operator’s experience at time t was measured in terms of number of embryo transfers performed before t.

MAIN RESULTS AND THE ROLE OF CHANCE

The heterogeneity among operators was highly significant (P value <0.001) and explained 44.5% of the total variability. The odds ratio of success of the worst operator in respect to the mean was equal to 0.84. For the best operator, the odds ratio of success was equal to 1.13 in respect to the mean. Based on the meta-analysis of the relationship between operator’s experience and success rate, it resulted that, on average, the operators’ performance did not improve with additional transfers.

LIMITATIONS, REASONS FOR CAUTION

At our center, operators become independent for ET’s after performing between 30 and 50 transfers under supervision. It is also possible that other relevant factors, such as embryologists on duty for the ET, have not been included in the present analysis and this may represent a potential bias. Among these, it should be mentioned that the embryologists on duty for the ET were not taken into consideration.

WIDER IMPLICATIONS OF THE FINDINGS

Continued performance analysis and the use of a digital simulator could help operators to test their expertise over time and either correct poor performance or avoid doing transfers.

STUDY FUNDING/COMPETING INTEREST(S)

None.

TRIAL REGISTRATION NUMBER

NCT03561129.

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.

PATIENTS

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

INTERVENTIONS

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 MEASURES

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.

RESULTS

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.

CONCLUSIONS

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.

The Influence Of Intrauterine Pressure On Embryo Retention In A Catheter After Embryo Transfer

The retention of the embryo in the transfer catheter after embryo transfer (ET) during in vitro fertilization is a very common phenomenon, encountered by even the most experienced operators, and embryos retained in the transfer catheter or its sleeve require a repeat transfer. The exact mechanism of embryo retention has not been explained. Therefore, the present study aimed to investigate the mechanism of embryo retention in the catheter during embryo transfer by using a transparent uterus model equipped with pressure sensors and a video recorder. The results indicate that pressure changes in the uterine cavity during ET can influence the distribution of the transferred fluid containing the embryo. Under certain conditions, the transferred fluid can flow backward in the catheter, which may lead to retention of the embryo in the catheter.

Prospective Randomized Trial Comparing Embryo Transfers of Cases with and without Catheter Rotation during Its Withdrawal

OBJECTIVE

To compare embryo transfer (ET) technique based on catheter rotation during its withdrawal in cases with unexplained infertility in a prospective, randomized trial (NCT03097042).

METHODS

Two hundred intracytoplasmic sperm injection (ICSI) patients undergoing ET with cleaving or blastocyst-stage fresh embryos were randomized into 2 groups: cases with (n = 100), and without (n = 100) catheter rotation during its withdrawal. Groups were matched for age and some clinical parameters. A soft catheter was used to transfer a single embryo with catheter rotation during its withdrawal in the study group and without rotation in the control. The use of a stiff catheter or tenaculum was not needed in any case. Groups were compared in terms of cycle characteristics and clinical pregnancy rates.

RESULTS

Pregnancy rate was significantly higher in the study group (41 vs. 26%, p = 0.04). Clinical pregnancy rate was also significantly higher in the study group (39 vs. 25%, OR 1.9 [1.1-3.5], p = 0.05). On the other hand, the ongoing pregnancy rate was similar between the 2 groups (33 vs. 23%, p = 0.2).

CONCLUSION

Catheter rotation during its withdrawal may be associated with increased pregnancy and clinical pregnancy rates; however, the difference in ongoing pregnancy rates did not reach statistical significance.

Difficult Embryo Transfer: A Systematic Review

We performed a systematic review on the clinical epidemiology and outcome of difficult embryo transfers (ETs) in infertility patients who present with difficult ET. We searched PubMed, ScienceDirect, and Elsevier journals from 1980 to June 2017. We aimed to determine the most successful method resulting in highest pregnancy rates (PRs) in patients with difficult ET. We identified 50 articles, in which 36 were reviewed and 15 were included. Analysis of the data collected showed that the majority of the difficult ETs were caused by cervical stenosis and the most common treatment was cervical dilation. We concluded that cervical dilation was effective at managing difficult ET. Hegar dilators used a minimum of 3 weeks before ET showed to have higher PR.

Inositol supplement improves clinical pregnancy rate in infertile women undergoing ovulation induction for ICSI or IVF-ET

OBJECTIVE

Pretreatment of myoinositol is a very new method that was evaluated in multiple small studies to manage poor ovarian response in assisted reproduction. This study was to determine the efficacy of myoinositol supplement in infertile women undergoing ovulation induction for intracytoplasmic sperm injection (ICSI) or in vitro fertilization embryo transfer (IVF-ET).

METHODS

A meta-analysis and systematic review of published articles evaluating the efficacy of myo-inositol in patients undergoing ovulation induction for ICSI or IVF-ET was performed.

RESULTS

Seven trials with 935 women were included. Myoinositol supplement was associated with significantly improved clinical pregnancy rate [95% confidence interval (CI), 1.04-1.96; P = .03] and abortion rate (95% CI, 0.08-0.50; P = .0006). Meanwhile, Grade 1 embryos proportion (95% CI, 1.10-2.74; P = .02), germinal vescicle and degenerated oocytes retrieved (95% CI, 0.11-0.86; P = .02), and total amount of ovulation drugs (95% CI, -591.69 to -210.39; P = .001) were also improved in favor of myo-inositol. There were no significant difference in total oocytes retrieved, MII stage oocytes retrieved, stimulation days, and E2 peak level.

CONCLUSIONS

Myoinositol supplement increase clinical pregnancy rate in infertile women undergoing ovulation induction for ICSI or IVF-ET. It may improve the quality of embryos, and reduce the unsuitable oocytes and required amount of stimulation drugs.

A prospective study comparing two embryo-transfer soft catheters

OBJECTIVES

To compare reproductive outcomes using two different soft catheters i.e. Set TDT® and Cook® Sydney IVF. The primary outcome was defined as a positive β-human chorionic gonadotropin (β-hCG) test.

METHODS

Our prospective study recruited 68 patients undergoing in vitro fertilization cycles in a private fertility clinic in Porto Alegre, Brazil, between January 2014 and April 2016. They were divided into two groups according to the catheter that would be used for the embryo transfer, and the groups were matched by age. The total number of patients in each group was: 34 for the TDT and 34 for the Cook Sydney. All the patients were submitted to a β-hCG test 12 days after the embryo transfer for pregnancy outcome evaluation.

RESULTS

Ten out of 34 patients from the TDT group had a positive outcome for pregnancy, corresponding to 29.4%. The Cook Sydney group had 9 patients out of 34 with positive outcomes, corresponding to 26.5%. Comparing the efficacy of both catheters for the primary outcome, there was no significant difference (p>0.05) between the TDT and the Cook Sydney catheters.

CONCLUSION

The TDT and the Cook Sydney catheters efficacies were similar for embryo transfer during assisted reproductive technology cycles.

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.

Large randomized trial comparing transabdominal ultrasound-guided embryo transfer with a technique based on uterine length measurement before embryo transfer

OBJECTIVE

To compare in a randomized, non-inferiority trial the embryo transfer (ET) technique based on uterine length measurement before transfer (ULMbET) with transabdominal ultrasound-guided embryo transfer (TA-UGET) in a large population of patients undergoing in-vitro fertilization (IVF).

METHODS

Patients undergoing IVF with ET with cleaving fresh embryos were randomized to receive ULMbET or TA-UGET. The transfer of one to three embryos on day 2-3 of culture was performed using a soft catheter either under transabdominal ultrasound guidance (TA-UGET group) or after measurement of the uterine cavity by transvaginal ultrasound and calculation of the discharge site (ULMbET group). The primary outcome measures were clinical pregnancy rate, ongoing pregnancy rate and implantation rate, and secondary outcomes included patient discomfort during ET.

RESULTS

A total of 1648 patients undergoing IVF were randomized to receive ULMbET (n = 828) or TA-UGET (n = 820) and were included in the analysis. Comparable clinical pregnancy rate (38.2% vs 38.9%), implantation rate (24.8% vs 25.2%) and ongoing pregnancy rate (33.1% vs 34.8%) were observed in ULMbET and TA-UGET groups. The discomfort intensity score and the proportion of patients with moderate-to-severe discomfort during ET were significantly higher in the TA-UGET group (2.6 vs 1.5 visual analog scale points and 19.8% vs 1.2%; P = 0.045 and P = 0.003, respectively).

CONCLUSION

The ULMbET technique leads to IVF results comparable to those obtained with UGET, but is better tolerated than is TA-UGET and is technically easier to perform for a single operator. Copyright © 2016 ISUOG. Published by John Wiley & Sons Ltd.

How often does the embryo implant at the location to which it was transferred?

OBJECTIVE

To determine how often the embryo implants exactly at the site of transfer and what additional factors may affect the eventual site of implantation in assisted reproductive technology (ART) cycles.

METHODS

This was a prospective observational study of women undergoing ART treatment in a tertiary university unit. Several factors inherent to the embryo transfer (ET), such as the location of the air bubbles and uterine contractility at 1 and at 60 min after ET were assessed with two-dimensional and three-dimensional (3D) ultrasound. In women in whom there was a resulting pregnancy, the position of the gestational sac (i.e. right, left, center or low) was subsequently assessed using 3D ultrasound, and predictors of its location were evaluated.

RESULTS

Of 239 recruited women with visualization of air bubbles at ET, 71 singleton gestational sacs were subsequently observed on 3D ultrasound. Overall, 40.8% (29/71) of embryos implanted at the location where the air bubbles were visualized at 1 min after ET, and 50.7% (36/71) implanted where the air bubbles were visualized at 60 min after ET (Cohen's kappa coefficients 0.21 and 0.37, respectively; comparison of agreement values: P = 0.28). Specifically, at 1 min the correspondence between the location of the air bubble and embryo implantation was 37.5% (6/16), 57.1% (8/14), 36.8% (7/19) and 36.4% (8/22) for right, left, central and lower uterus, respectively (4 × 4 contingency table, P < 0.01); at 60 min, the correspondence was 72.2% (13/18), 50.0% (9/18), 33.3% (8/24) and 85.7% (6/7), respectively (5 × 4 contingency table, P < 0.001). In addition, higher vs lower frequency of uterine contractions at 60 min was associated with different sites of implantation (5.6% (1/18), 11.1% (2/18), 27.8% (5/18) and 55.6% (10/18) vs 34.0% (18/53), 24.5% (13/53), 13.2% (7/53) and 28.3% (15/53) for right, left, central and lower uterus, respectively, P < 0.05). In particular, a high uterine contraction frequency following ET was associated with a twofold increased chance of the pregnancy implanting in the lower part of the uterine cavity (relative risk, 1.96 (95% CI, 1.08-3.56), P < 0.05).

CONCLUSIONS

The position of the air bubbles within the first 60 min of ET appears to predict the site of implantation in approximately half of cases, denoting an overall poor agreement. This implies significant embryo migration, and has important clinical implications, as it demonstrates that other factors such as uterine contractility may dictate where the embryo will eventually implant following transfer. Copyright © 2015 ISUOG. Published by John Wiley & Sons Ltd.

Absolute position versus relative position in embryo transfer: a randomized controlled trial

BACKGROUND

Meta-analysis revealed that embryo placement 20 mm from the fundal endometrial surface resulted in higher pregnancy rate, ongoing pregnancy rate, and live birth rate compared with placement 10 mm from the fundal endometrial surface. Pregnancy and implantation rates according to relative position were higher when the catheter tip was positioned close to the middle of the endometrial cavity. The aim of the current study is to evaluate differences in implantation and pregnancy rates if the site of embryo transfer is 2 cm distance from the fundal endometrium (DFE) compared to the midpoint of the endometrial cavity length (ECL).

METHODS

Patients were randomized to one of two groups: in group A (n = 98, 98 IVF-ET cycles), the embryo transfer catheter tip was positioned 2 cm DFE, while that in group B (n = 97, 97 IVF-ET cycles) was positioned at the midpoint of the ECL. We compared pregnancy outcomes of implantation rate, chemical pregnancy rate, clinical pregnancy rate, ongoing pregnancy rate, ectopic pregnancy rate, and miscarriage rate in the two groups.

RESULTS

Analysis of implantation rate (19.5 ± 27.7 vs. 21.7 ± 32.6; p = 0.6), chemical pregnancy rate (51 % vs. 50.5 %; p = 0.94), clinical pregnancy rate (35.7 % vs. 38.1 %; p = 0.73), ongoing pregnancy rate (31.6 % vs. 30.9 %; p = 0.92), ectopic pregnancy rate (8.6 % vs. 2.7 %; p = 0.35), and miscarriage rate (11.4 % vs. 16.2 %; 0.74) revealed comparable results for both groups.

CONCLUSIONS

Implantation and pregnancy rates were not influenced by the site of the ET catheter tip being 2 cm DFE compared to at the midpoint of the ECL.

ISRCTN

ISRCTN15972342.

Ultrasound guidance during embryo transfer: a systematic review and meta-analysis of randomized controlled trials

OBJECTIVES

To summarize the current evidence on the effect of using ultrasound (US) guidance during embryo transfer (ET).

METHODS

In this systematic review, we included randomized controlled trials examining the effect of the use of US guidance during ET; data from studies using the same catheter type in study arms were not pooled with the results from studies that used different catheter types.

RESULTS

Twenty-one studies were included in the quantitative analysis: 18 compared 'US guidance' with 'clinical touch', of which one was subsequently excluded from the quantitative meta-analysis owing to a lack of available data, three studies compared transvaginal US guidance with transabdominal US guidance, and one study compared 'hysterosonometry before ET' with US guidance. Comparison of the use of US guidance with clinical touch, in studies that used the same catheter type in the study arms, indicated a benefit of using US guidance during ET on the rates of live birth (relative risk (RR), 1.48 (95% CI, 1.16-1.87)), based on two studies involving 888 women with moderate-quality evidence, and on the rates of clinical pregnancy (RR, 1.32 (95% CI, 1.18-1.46)), based on 13 studies involving 3641 women with high-quality evidence. However, when comparing the use of US guidance with clinical touch in studies that used different catheter types, the results suggest that using US guidance during ET has no effect on the rates of reproductive outcome: live birth (RR, 0.99 (95% CI, 0.83-1.19)), based on one study involving 1649 women with moderate-quality evidence; clinical pregnancy (RR, 1.04 (95% CI, 0.89-1.21)), based on five studies involving 2949 women with moderate-quality evidence. The estimates for the rate of miscarriage and for the other identified comparisons were imprecise.

CONCLUSIONS

The available evidence suggests that there is a benefit of using US guidance during ET. However, both US-guided transfer and clinical touch should be considered acceptable, as the benefit of US is not large and should be balanced against the increased cost and need to change the catheter type. More studies are required before conclusions can be drawn regarding the effect of other techniques on reproductive outcome.

Reporting of embryo transfer methods in IVF research: a cross-sectional study

The reporting of embryo transfer methods in IVF research was assessed through a cross-sectional analysis of randomized controlled trials (RCTs) published between 2010 and 2011. A systematic search identified 325 abstracts; 122 RCTs were included in the study. Embryo transfer methods were described in 42 out of 122 articles (34%). Catheters (32/42 [76%]) or ultrasound guidance (31/42 [74%]) were most frequently mentioned. Performer 'blinding' (12%) or technique standardization (7%) were seldom reported. The description of embryo transfer methods was significantly more common in trials published by journals with lower impact factor (less than 3, 39.6%; 3 or greater, 21.5%; P = 0.037). Embryo transfer methods were reported more often in trials with pregnancy as the main end-point (33% versus 16%) or with positive outcomes (37.8% versus 25.0%), albeit not significantly. Multivariate logistic regression confirmed that RCTs published in higher impact factor journals are less likely to describe embryo transfer methods (OR 0.371; 95% CI 0.143 to 0.964). Registered trials, trials conducted in an academic setting, multi-centric studies or full-length articles were not positively associated with embryo transfer methods reporting rate. Recent reports of randomized IVF trials rarely describe embryo transfer methods. The under-reporting of research methods might compromise reproducibility and suitability for meta-analysis.

Embryo catheter loading and embryo culture techniques: results of a worldwide Web-based survey

PURPOSE

To identify trends in embryo catheter loading and embryo culture techniques performed worldwide.

METHODS

A retrospective evaluation using the results of a web-based survey, (IVF Worldwide ( www.IVF-worldwide.com ), was performed.

RESULTS

Responses from 265 centers in 71 countries were obtained. Most centers (97 %) preferred a catheter with its orifice on top, with only 3 % preferring a catheter with the orifice on its side; 41 % preferred a catheter marked for clear ultrasound view. The most commonly-reported methods of embryo loading were medium-air-embryo-air-medium (42 %), medium in catheter with embryo at end (20 %) and medium-air-embryo (15 %). In 68 % of centers the final volume of the catheter was up to 0.3 ml, with only 19 % using 0.3-0.5 ml and 1 % using 0.5-0.7 ml. Using reduced oxygen concentrations for embryo culture was divided between those who used it in combination with the two-gas system (34 %) and those who did not use it at all (39 %); 24 % reported using a three-gas system. Most clinics using reduced oxygen concentrations used it throughout the entire culture period. Half of centers (51 %) reported using reduced oxygen concentrations for the entire IVF population while 6 % reserved it only for blastocyst transfer. The use of sequential media was highly dominant with 40 % reporting its use.

Embryo transfer

Embryo transfer is a critical step in the overall success of in vitro fertilization (IVF). Despite its apparent simplicity, it is an integral part of the IVF cycle that can be difficult to teach and perform well. In this chapter we describe the procedure of embryo transfer and discuss various modifications that have been evaluated in an effort to improve the probability of embryo implantation including ultrasound guidance, catheter design, transfer technique, as well as enrichment of the embryo transfer media.

Assisted reproductive techniques

Assisted reproductive technologies (ART) encompass fertility treatments, which involve manipulations of both oocyte and sperm in vitro. This chapter provides a brief overview of ART, including indications for treatment, ovarian reserve testing, selection of controlled ovarian hyperstimulation (COH) protocols, laboratory techniques of ART including in vitro fertilization (IVF), and intracytoplasmic sperm injection (ICSI), embryo transfer techniques, and luteal phase support. This chapter also discusses potential complications of ART, namely ovarian hyperstimulation syndrome (OHSS) and multiple gestations, and the perinatal outcomes of ART.

Modeling Embryo Transfer into a Closed Uterine Cavity

Embryo transfer (ET) is the last manual intervention after extracorporeal fertilization. After the ET procedure is completed, the embryos are conveyed in the uterus for another two to four days due to spontaneous uterine peristalsis until the window time for implantation. The role of intrauterine fluid flow patterns in transporting the embryos to their implantation site during and after ET was simulated by injection of a liquid bolus into a two-dimensional liquid-filled channel with a closed fundal end via a liquid-filled catheter inserted in the channel. Numerical experiments revealed that the intrauterine fluid field and the embryos transport pattern were strongly affected by the closed fundal end. The embryos re-circulated in small loops around the vicinity where they were deposited from the catheter. The transport pattern was controlled by the uterine peristalsis factors, such as amplitude and frequency of the uterine walls motility, as well as the synchronization between the onset of catheter discharge and uterine peristalsis. The outcome of ET was also dependent on operating parameters such as placement of the catheter tip within the uterine cavity and the delivery speed of the catheter load. In conclusion, this modeling study highlighted important parameters that should be considered during ET procedures in order to increase the potential for pregnancy success.

Assisted reproduction outcomes after embryo transfers requiring a malleable stylet

OBJECTIVE

This retrospective case-control study was undertaken to assess the impact of a malleable stylet application on embryo transfer (ET) outcome.

METHODS

The Wallace malleable stylet was used when the soft inner catheter could not negotiate the internal os during ultrasound-guided ET. Patients having an age ≤37 years, with three embryos replaced were included in the analysis. Implantation rate, clinical pregnancy rate and live birth rate were the main outcome measures.

RESULTS

The Wallace malleable stylet was applied in 164 (29.6%) of the 553 ETs evaluated. Implantation rate, clinical pregnancy rate and live birth rate showed a 5.6% (19.4% vs. 13.8%), a 10.8% (41.9% vs. 31.1%) and a 9.9% (37.3% vs. 27.4%) absolute difference, respectively, in favor of ETs not requiring the stylet. These differences were statistically significant (P < 0.05).

CONCLUSIONS

ETs requiring stylet are associated with lower implantation, clinical pregnancy and live birth rates.

Hysteroscopic evaluation of endocervical and endometrial lesions observed after different procedures of embryo transfer: a prospective comparative study

OBJECTIVE

Endocervical and endometrial damage observed after different procedures of embryo transfer (ET) were investigated using diagnostic hysteroscopy.

STUDY DESIGN

Prospective, descriptive and comparative study, in an Infertility centre, University Hospital. Hundred consecutive infertile patients with a normal uterine cavity, included in an IVF program, were enrolled between May 1st, 2006 and April 30th, 2007. All the patients had a diagnostic hysteroscopy immediately after trial ET using soft ET catheters: (i) IVF Sydney Set (Cook, Limerick, Ireland) (n=27), (ii) Elliocath (Ellios, Paris, France) (n=34), (iii) Frydman classic 4.5 (CCD, Paris, France) (n=19), and rigid ET catheters: Memory Frydman 4.5 (CCD, Paris, France) (n=20). All the procedures were recorded and blindly reviewed. Data were analyzed using a Kruskal-Wallis test for age and severity of endometrial lesions, or Fisher's exact test for binary criteria.

RESULTS

Endocervical lesions were more frequently encountered in the soft (63%) and rigid (85%) Frydman's catheter groups compared to other groups (Elliocath: 29%, IVF Sydney Set: 26%; p<0.0001). Presence of blood on the catheter, and endometrial lesions were significantly less frequent in soft catheter groups compared to the rigid catheter group (p<0.0001). Severe endometrial lesions were less frequently observed when soft catheters were used (85%, 53%, 32%, 11% for Memory Frydman, Frydman classic, Elliocath and IVF Sydney Set, respectively; p<0.0001). The presence of blood on the catheter signed severe endometrial lesions.

CONCLUSION

All ET catheters can lead to endocervical and endometrial damage. Severe endometrial lesions were less frequent when soft catheters were used.

Intrauterine insemination and male subfertility

In this article we define male subfertility, review clinical indications for the use of intrauterine insemination, evaluate insemination preparation and administration technique, and ultimately advocate for its use as a first-line therapy in the treatment of infertile couples with male subfertility.

Firm versus soft embryo transfer catheters under ultrasound guidance: Does catheter choice really influence the pregnancy rates?

In contrast to the previously published evidence, under ultrasound guidance, individual catheter choice does not statistically significantly affect the clinical pregnancy rate in a modern clinical IVF practice. This may be as a result of decreasing the incidence of difficult transfers and endometrial injury with ET under ultrasound guidance.

Prospective randomized comparison of Wallace and Labotect embryo transfer catheters

The aim of this study was to compare the clinical performance of Wallace and Labotect embryo transfer catheters in a single assisted reproduction centre. A total of 260 women undergoing embryo transfer were randomized between Wallace and Labotect catheters. When both catheters failed to negotiate the cervical canal, the transfer was accomplished with a stiff catheter. Intention to treat analysis revealed that Wallace and Labotect embryo transfer catheters yielded statistically similar clinical pregnancy (44.6 versus 34.6%), implantation (23.2 versus 18.9%) and ongoing pregnancy (38.5 versus 27.7%) rates. As treated analysis revealed clinical pregnancy rates of 42.5 versus 35.4%, implantation rates of 22.3 versus 20.6% and ongoing pregnancy rates of 36.8 versus 28.3% with Wallace and Labotect catheters respectively. Catheter change due to unsuccessful negotiation of the internal cervical os was significantly more frequently necessary when embryo transfer was first intended with the Wallace than the Labotect catheter (P < 0.001; 33 and 2% respectively). Although not being statistically significant, the observed differences may be regarded as clinically important and may reach statistical significance in larger trials. More trials are necessary before reaching a definitive conclusion regarding the performance of the Labotect embryo transfer catheter.

Is what we clearly see really so obvious? Ultrasonography and transcervical embryo transfer—a review

OBJECTIVE

To critically review the role of ultrasound-guided embryo transfer (ET) and its influence on the outcome of in vitro fertilization (IVF).

DESIGN

Medline review of published manuscripts.

RESULT(S)

Studies evaluating the role of ultrasound-assisted ET have had mixed results, and although meta-analysis of prospective trials suggests an improvement in outcome, limitations in study design may overstate the effect of ultrasonography. Other ET techniques may eliminate the advantages provided by ultrasonography, limiting its benefit to specific clinical scenarios. However, because no trial has demonstrated an adverse effect and because cases that may benefit from its use often cannot be predicted reliably, the routine application of ultrasonography can be justified.

What can the clinician do to improve implantation?

Implantation is a complicated process that requires the orchestration of a series of events involving both the embryo and the endometrium. Even with the transfer of high quality embryos, implantation rates remain relatively low. The growing tendency towards transferring fewer embryos provides further incentives to improve implantation rates. In this article, the various clinical strategies employed to increase the chance of implantation are reviewed. Embryo transfer technique is a critical step in assisted reproductive technology cycles. Recent studies have shown significant improvements in clinical pregnancy rates resulting from careful embryo transfer technique, appropriate catheter type and placing for embryo transfer. Increasingly, adjuvant pharmaceutical therapies are also being applied with the aim of improving embryo implantation. However, the evidence for their efficacy and safety is limited. Recent evidence suggests that adoption of milder ovarian stimulation regimens may provide a more effective clinical approach to improving implantation, since beneficial effects have been shown for both endometrial receptivity and embryo quality.