Evidence and consensus on technical aspects of embryo transfer

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.