An analysis of the impact of embryo transfer difficulty on live birth rates, using a standardised grading system

The impact of difficult embryo transfer on the success of IVF: a systematic review and meta-analysis

The procedure of embryo transfer (ET) must be as gentle as possible since any traumatism may cause uterine contractility that interferes with the implantation. However, this ideal conduct is not always possible, and additional measures may be necessary (difficult ET). Different studies have evaluated the impact of difficult ET on the clinical pregnancy rate (CPR), but results were not univocal. The present systematic review and meta-analysis was aimed to provide a precise estimate of the possible detrimental effects of difficult ET on CPR. The study protocol was registered online (PROSPERO number: CRD42023387197). An electronic database search was performed to identify articles published until September 2022. The primary outcome was CPR. Fifteen studies fulfilled the inclusion criteria. Difficult ET significantly reduced the CPR (OR 0.70; 95%CI: 0.64-0.76; p < 0.0001. All pre-planned subgroup analyses according to study design (retrospective vs prospective studies), historical period (studies published before and after 2010), type of catheter, frequency of difficult cases (> or < 19%) and pregnancy rate (> or < 38%) confirmed the significant association. Difficult ET is associated with a significant reduction of CPR. Further studies are warranted to understand how to prevent or manage this common clinical situation.

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.

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.

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.

Impact of anxiety levels on difficulty of intrauterine insemination and treatment outcomes

AIM

The objective of this study was to determine the effect of anxiety on intrauterine insemination (IUI) results in couples with unexplained infertility. Second, the relationship between difficulty level of IUI procedure and anxiety were investigated.

METHODS

A total of 100 women undergoing first IUI treatment were enrolled into this prospective cross-sectional study. Participants were asked to complete the Beck Anxiety Inventory (BAI) before the IUI procedure and classified into two groups according to the anxiety score (minimal anxiety; BAI score <8, n = 73 and mild-to-moderate anxiety; BAI score ≥8, n = 27). Cervical condition was evaluated with speculum and presence of congenital anomalies, extensive leucorrhea or polypoid lesions were classified as unfavorable cervix. All of the patients were evaluated for difficulty of IUI and asked to state the severity of their pain with a visual analog scale after the procedure. Clinical pregnancy rates were also analyzed.

RESULTS

There was no statistically significant difference between the groups in terms of pregnancy rates (12.3% vs 14.8%, P = 0.743). visual analog scale score was significantly higher in mild-to-moderate anxiety group (P = 0.002). Anxiety levels were higher in patients with difficult IUI (10.5 vs 4.3, P < 0.001). In multivariate analysis, higher BAI scores (odds ratio: 1.1, 95% confidence interval: 1.0-1.2, P = 0.01) and unfavorable cervical condition (odds ratio: 3.6, 95% confidence interval: 1.2-10.7, P = 0.01) emerged as independent predictors for difficulty of IUI.

CONCLUSION

Evaluation of anxiety before IUI might help to predict difficulty of IUI and related pain. Although anxiety increases the difficulty of IUI, it does not affect pregnancy outcomes of the treatment.

The Effect of Atosiban on Patients With Difficult Embryo Transfers Undergoing In Vitro Fertilization-Embryo Transfer

The purpose of this study was to evaluate the effect of atosiban on the outcomes of infertile women undergoing in vitro fertilization (IVF) with difficult embryo transfers (ETs). This randomized double-blind study enrolled 204 infertile women with difficult ETs during IVF treatment between June 2014 and June 2018. According to a computer-generated randomization list, participants were randomized into placebo (n = 102) and atosiban (n = 102) groups. In atosiban group, atosiban with a total dose of 37.5 mg was administered. All of the patients underwent IVF-ET using cryopreserved embryos. The clinical pregnancy rate per cycle and implantation rate per transfer (45.1% and 26.5%) in atosiban group were significantly higher than those of placebo group (15.6% and 9.7%, respectively; P < .05). This study showed that administration of atosiban during ET was extraordinarily effective for patients with difficult transfers.

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.

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.

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.

Does the Presence of Blood in the Catheter or the Degree of Difficulty of Embryo Transfer Affect Live Birth?

The technique used for embryo transfer (ET) can affect implantation. Prior research that evaluated the effect of postprocedural blood of the transfer catheter tip have yielded mixed results, and it is unclear whether this is actually a marker of difficulty of the transfer. Our objective was to estimate the effect of blood at the time of ET and the difficulty of ET on live birth rates (LBR). This retrospective cohort study utilized generalized estimating equations (GEEs) with nesting for repeated cycles for all analyses. Univariate modeling was performed and a final multivariate (adjusted) GEE model accounted for all significant confounders. Embryo transfers were subjectively graded (easy, medium, or hard) by a physician at the time of transfer. The presence of blood at ET was associated with more difficult ETs, retained embryos, and presence of mucous in the catheter. In the univariate analysis, ET with blood was not associated with live birth, while the degree of difficulty for ET had a negative impact on LBR. In the final multivariate GEE model, which accounts for repeated cycles from a patient, the only factors associated with an increased LBR were the degree of difficulty of the ET, female age, and blastocyst transfer. After controlling for confounding variables, the presence of blood in the transfer catheter was not associated with the likelihood of pregnancy and thus was not an independent predictor of cycle outcome. This indicates that the difficulty of the transfer itself was a strong negative predictor of pregnancy.