Sequential cleavage and blastocyst embryo transfer and IVF outcomes: a systematic review

Effects of intrauterine infusion of autologous platelet-rich plasma gel on endometrial thickness and outcomes of frozen-thawed embryo transfer in women with thin endometrium

PURPOSE

The purpose of this study is to determine whether intrauterine infusion of autologous platelet-rich plasma (PRP) gel increases endometrial thickness (EMT) and improves the outcomes of frozen-thawed embryo transfer (FET) in women with thin endometrium.

METHODS

This study included 111 women (aged 25-44 years) who had thin endometrium. All patients had at least one previous cycle canceled because of thin endometrium or previous embryo transfer cycles and an EMT < 7 mm. Forty-seven women underwent intrauterine infusion of autologous PRP gel on three occasions during endometrial preparation and the remaining women served as controls. The final EMT was measured by ultrasound before the start of the luteal phase, and FET-related outcome parameters were monitored.

RESULTS

Mean EMT was greater in women who received PRP gel than in those who did not (6.7 mm vs. 6.3 mm, respectively, p < 0.05). FET was attempted in all women. The 47 women who underwent infusion of PRP had a significantly higher pregnancy rate (18 pregnancies (38.3%), with 17 (36.2%) ongoing) compared with 64 control women (ten pregnancies (18.5%), nine (16.7%) ongoing). However, there was no significant reduction in the miscarriage rate.

CONCLUSION

Intrauterine infusion of autologous PRP gel during endometrial preparation for FET cycles can improve the EMT, clinical pregnancy rate, and ongoing pregnancy rate in women with thin endometrium.

Effect of sequential cleavage and blastocyst embryo transfer compared to single cleavage stage embryo transfer on assisted reproductive technology outcome: An RCT

Background

Assisted reproductive technology (ART), offers hope for many infertile couples by increasing the chance of successful pregnancy. The success of in vitro fertilization depends on various factors, in which embryo transfer (ET) is one of the critical steps influencing in vitro fertilization success rates. Extended embryo culture and blastocyst-stage ET have been considered in ART due to their potential benefits including improved implantation rates.

Objective

This study aimed to compare the outcomes of sequential ET vs single cleavage-stage ET in women undergoing a fresh ET cycle with a limited number of embryos.

Materials and Methods

This randomized clinical trial was conducted on 140 women undergoing infertility treatments and candidates for fresh ET at the Research and Clinical Center for Infertility, Yazd, Iran from August 2023 to January 2024. Women with a number of embryos from 2-5 ( ≥ 2 and ≤ 5 available embryos) were randomly divided into 2 groups: One group underwent sequential ET (one cleavage-stage ET followed by one blastocyst ET) and the other group underwent single-step 2 cleavage-stage ET. The primary outcome was clinical pregnancy, and the secondary outcome included chemical pregnancy and early abortion rates.

Results

Our findings showed significantly higher rates of clinical (33.5% vs 13.6%, p = 0.003) and chemical (41.3% vs 18.2%, p = 0.004) pregnancies in the sequential ET group compared to the single-step cleavage ET group. The early abortion rate was higher in single-step cleavage ET (13% vs 44.4%, p = 0.053).

Conclusion

Sequential fresh ET is a useful choice in women who have a limited number of embryos and can improve ART outcomes.

Predictive models of recurrent implantation failure in patients receiving ART treatment based on clinical features and routine laboratory data

STUDY QUESTION

The objective was to construct a model for predicting the probability of recurrent implantation failure (RIF) after assisted reproductive technology (ART) treatment based on the clinical characteristics and routine laboratory test data of infertile patients. A model was developed to predict RIF. The model showed high calibration in external validation, helped to identify risk factors for RIF, and improved the efficacy of ART therapy.

WHAT IS KNOWN ALREADY

Research on the influencing factors of RIF has focused mainly on embryonic factors, endometrial receptivity, and immune factors. However, there are many kinds of examinations regarding these aspects, and comprehensive screening is difficult because of the limited time and economic conditions. Therefore, we should try our best to analyse the results of routine infertility screenings to make general predictions regarding the occurrence of RIF.

STUDY DESIGN, SIZE, DURATION

A retrospective study was conducted with 5212 patients at the Reproductive Center of the First Affiliated Hospital of USTC from January 2018 to June 2022.

PARTICIPANTS/MATERIALS, SETTING, METHODS

This study included 462 patients in the RIF group and 4750 patients in the control group. The patients' basic characteristics, clinical treatment data, and laboratory test indices were compared. Logistic regression was used to analyse RIF-related risk factors, and the prediction model was evaluated by receiver operating characteristic (ROC) curves and the corresponding areas under the curve (AUCs). Further analysis of the influencing factors of live births in the first cycle of subsequent assisted reproduction treatment in RIF patients was performed, including the live birth subgroup (n = 116) and the no live birth subgroup (n = 200).

MAIN RESULTS AND THE ROLE OF CHANCE

(1) An increased duration of infertility (1.978; 95% CI, 1.264-3.097), uterine cavity abnormalities (2.267; 95% CI, 1.185-4.336), low AMH levels (0.504; 95% CI, 0.275-0.922), insulin resistance (3.548; 95% CI, 1.931-6.519), antinuclear antibody (ANA)-positive status (3.249; 95% CI, 1.20-8.797) and anti-β2-glycoprotein I antibody (A-β2-GPI Ab)-positive status (5.515; 95% CI, 1.481-20.536) were associated with an increased risk of RIF. The area under the curve of the logistic regression model was 0.900 (95% CI, 0.870-0.929) for the training cohort and 0.895 (95% CI, 0.865-0.925) for the testing cohort. (2) Advanced age (1.069; 95% CI, 1.015-1.126) was a risk factor associated with no live births after the first cycle of subsequent assisted reproduction treatment in patients with RIF. Blastocyst transfer (0.365; 95% CI = 0.181-0.736) increased the probability of live birth in subsequent cycles in patients with RIF. The area under the curve of the logistic regression model was 0.673 (95% CI, 0.597-0.748).

LIMITATIONS, REASONS FOR CAUTION

This was a single-centre regression study, for which the results need to be evaluated and verified by prospective large-scale randomized controlled studies. The small sample size for the analysis of factors influencing pregnancy outcomes in subsequent assisted reproduction cycles for RIF patients resulted in the inclusion of fewer covariates, and future studies with larger samples and the inclusion of more factors are needed for assessment and validation.

WIDER IMPLICATIONS OF THE FINDINGS

Prediction of embryo implantation prior to transfer will facilitate the clinical management of patients and disease prediction and further improve ART treatment outcomes.

STUDY FUNDING/COMPETING INTEREST(S)

This work was supported by the General Project of the National Natural Science Foundation of China (Nos. 82,201,792, 82,301,871, 81,971,446, and 82,374,212) and the Natural Science Foundation of Anhui Province (No. 2208085MH206). There are no conflicts of interest to declare.

TRIAL REGISTRATION NUMBER

This study was registered with the Chinese Clinical Trial Register (Clinical Trial Number: ChiCTR1800018298 ).

Sequential embryo transfer combined with intrauterine perfusion improved pregnancy outcomes in patients with recurrent implantation failure

OBJECTIVE

To compare the application of sequential embryo transfer, cleavage embryo transfer, and blastocyst transfer combined with intrauterine perfusion in frozen-thawed embryo transfer cycles in patients with recurrent implantation failure to provide a reference for reproductive clinicians.

METHODS

The 166 patients who underwent frozen-thawed embryo transfer due to recurrent implantation failure in the reproductive center from January 2021 to March 2022 were retrospectively analyzed. According to the different embryos transferred, they were divided into cleavage embryo transfer groups (72 cases in Group A), blastocyst transfer group (29 cases in Group B), and sequential transfer group (65 cases in Group C). All three groups were treated with intrauterine perfusion 5 days before embryo transfer. The general data and clinical pregnancy outcome indicators, such as embryo implantation rate, clinical pregnancy rate, ongoing pregnancy rate, live birth rate, twin rate, were compared among the three groups.

RESULTS

The embryo implantation rate (53.1%), clinical pregnancy rate (76.9%), ongoing pregnancy rate (67.7%) and live birth rate(66.15%) in the sequential transfer group were significantly higher than those in the other two groups (P < 0.05), and the ectopic pregnancy rate was lower in the sequential transfer group.

CONCLUSION

Sequential transfer combined with intrauterine perfusion partially improves clinical pregnancy outcomes and reduces the risk of ectopic pregnancy in frozen embryo cycle transfers in patients with recurrent implantation failure, which may be a favourable transfer reference strategy for patients with recurrent implantation failure.

Embryo Transfer Strategies for Women with Recurrent Implantation Failure During the Frozen-thawed Embryo Transfer Cycles: Sequential Embryo Transfer or Double-blastocyst Transfer?

OBJECTIVE

Both sequential embryo transfer (SeET) and double-blastocyst transfer (DBT) can serve as embryo transfer strategies for women with recurrent implantation failure (RIF). This study aims to compare the effects of SeET and DBT on pregnancy outcomes.

METHODS

Totally, 261 frozen-thawed embryo transfer cycles of 243 RIF women were included in this multicenter retrospective analysis. According to different embryo quality and transfer strategies, they were divided into four groups: group A, good-quality SeET (GQ-SeET, n=38 cycles); group B, poor-quality or mixed-quality SeET (PQ/MQ-SeET, n=31 cycles); group C, good-quality DBT (GQ-DBT, n=121 cycles); and group D, poor-quality or mixed-quality DBT (PQ/MQ-DBT, n=71 cycles). The main outcome, clinical pregnancy rate, was compared, and the generalized estimating equation (GEE) model was used to correct potential confounders that might impact pregnancy outcomes.

RESULTS

GQ-DBT achieved a significantly higher clinical pregnancy rate (aOR 2.588, 95% CI 1.267-5.284, P=0.009) and live birth rate (aOR 3.082, 95% CI 1.482-6.412, P=0.003) than PQ/MQ-DBT. Similarly, the clinical pregnancy rate was significantly higher in GQ-SeET than in PQ/MQ-SeET (aOR 4.047, 95% CI 1.218-13.450, P=0.023). The pregnancy outcomes of GQ-SeET were not significantly different from those of GQ-DBT, and the same results were found between PQ/MQ-SeET and PQ/MQ-DBT.

CONCLUSION

SeET relative to DBT did not seem to improve pregnancy outcomes for RIF patients if the embryo quality was comparable between the two groups. Better clinical pregnancy outcomes could be obtained by transferring good-quality embryos, no matter whether in SeET or DBT. Embryo quality plays a more important role in pregnancy outcomes for RIF patients.

A Case Series Based on the Mixed Double-Embryo Transfer (MDET) Outcome in Patients With Recurrent Implantation Failure

Successful implantation of embryos depends on the synchronous cross-talks between the endometrial wall and the competent blastocyst within the window of implantation (WOI). Hence, the WOI has a major significance in assisted reproductive technology (ART). However, in some cases, women do not have fixed WOI in ART cycles in order to enhance the rate of successful clinical pregnancy. However, there have been stances where women do not have a fixed WOI, and it shifts in subsequent menstrual periods. This contributes to the chances of recurrent implantation failure (RIF). Another factor that contributes to RIF is erratic endometrial receptivity, which hinders the chances of successful implantation of the conceptus in the endometrium. This case series consists of four case studies where the patients were believed to be suffering from RIF due to variable WOI or erratic endometrial receptivity and the routine protocol followed nowadays failed to make them conceive. In order to resolve the condition, we proposed a novel strategy in an attempt to improve pregnancy rates in these cases. An innovative method of embryo transfer known as mixed double-embryo transfer (MDET), which involved the transfer of one day 3 embryo and one day 5 blastocyst on day 6 of progesterone, led to possible pregnancy outcomes. A viable pregnancy was validated based on the human chorionic gonadotropin (β-hCG) test report, and two of the cases delivered healthy babies. Thus, this case series provides a unique approach to addressing the issues of RIF. However, larger studies are required to validate the possible use of this technique.

Obstetric and Neonatal Outcomes After Transferring More Than One Embryo in Patients With Preimplantation Genetic Testing

OBJECTIVE

To compare obstetric and neonatal outcomes after single embryo transfer (SET) compared with multiple embryo transfer (MET) from frozen-thawed transfer cycles of embryos that underwent preimplantation genetic testing for aneuploidies (PGT-A).

METHODS

We conducted a retrospective cohort study from the SART CORS (Society for Assisted Reproductive Technology Clinic Outcome Reporting System) national database. Clinical and demographic data were obtained from the SART CORS database for all autologous and donor egg frozen-thawed transfer cycles of embryos that underwent PGT-A between 2014 and 2016, after excluding cycles that used frozen oocytes, fresh embryo transfer, and transfers of embryos from more than one stimulation cycle. Multivariable linear and log-binomial regression models were used to estimate the relative and absolute difference in live-birth rate, multiple pregnancy rate, gestational age at delivery, and birth weight between SET compared with MET.

RESULTS

In total, 15,638 autologous egg transfer cycles and 944 donor egg transfer cycles were analyzed. Although the live-birth rate was higher with MET compared with SET in the autologous oocyte cycles (64.7% vs 53.2%, relative risk [RR] 1.24, 95% CI, 1.20-1.28), the multiple pregnancy rate was markedly greater (46.2% vs 1.4%, RR 32.56, 95% CI, 26.55-39.92). Donor oocyte cycles showed similar trends with an increased live-birth rate (62.0% vs 49.7%, RR 1.26, 95% CI, 1.11-1.46) and multiple pregnancy rate (54.0% vs 0.8%) seen with MET compared with SET. Preterm delivery rates and rates of low birth weight were significantly higher in MET compared with SET in both autologous and donor oocyte cycles and were also higher in the subanalysis of singleton deliveries that resulted from MET compared with SET.

CONCLUSION

Despite some improvement in live-birth rate, nearly half of the pregnancies that resulted from MET of embryos that underwent PGT-A were multiples. Compared with SET, MET is associated with significantly higher rates of neonatal morbidity, including preterm delivery and low birth weight. The transfer of more than one embryo that underwent PGT-A should continue to be strongly discouraged, and patients should be counseled on the significant potential for adverse outcomes.

Impact of Caesarean section on pregnancy outcomes in ART after transfer of one or more frozen blastocysts

INTRODUCTION

The prevalence of Caesarean delivery is rising steadily worldwide, and it is important to identify its future impact on fertility. A number of articles have been published on this subject, but the impact of Caesarean section on reproductive outcomes is still under debate, and none of these articles focus exclusively on frozen blastocysts.

OBJECTIVE

The aim of this study was to evaluate the impact of a previous Caesarean delivery compared with a previous vaginal delivery on the chances of a live birth following the transfer of one or more frozen embryos at the blastocyst stage.

METHODS

This was a retrospective, bicentric study at the University Hospitals of Nîmes and Montpellier, conducted between January 1st, 2016 and February 1st, 2021. Three hundred and ninety women with a history of childbirth and a transfer of one or more frozen embryos at blastocyst stage were included in the analysis. The primary outcome was the number of live births. Secondary outcomes were: the rate of positive HCG, miscarriage, ectopic pregnancy and clinical pregnancy, as well as the live birth rate according to the presence or absence of an isthmocele.

RESULTS

Of the 390 patients included, 118 had a previous Caesarean delivery and 272 a vaginal delivery. No statistically significant differences were found for the primary (p = 0.9) or secondary outcomes. A trend towards lower live birth rates was observed in patients with isthmoceles, but this did not reach significance (p>0.9). On the other hand, transfers were more often described as difficult in the Caesarean delivery group (p = 0.011).

CONCLUSION

Our study found no effect of previous Caesarean delivery on the chances of live birth after transferring one or more frozen blastocysts. However, further prospective studies are needed to confirm these results.

Effect of sequential embryo transfer on in vitro fertilization and embryo transfer outcomes: a systematic review and meta-analysis

Background

Sequential embryo transfer has been recognized as a strategy to increase pregnancy rates in women undergoing in vitro fertilization and embryo transfer (IVF-ET). However, its impact on assisted reproductive outcomes remains to be substantiated by robust evidence. This systematic review aims to summarize and analyze the available evidence to investigate the effect of sequential embryo transfer on assisted reproductive outcomes.

Methods

A comprehensive literature search was executed across the Pubmed, Cochrane Library, Web of Science, and Scopus databases in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Data were aggregated utilizing a random effects model, and the resultant outcomes were articulated as odds ratios (ORs) along with their 95% confidence intervals (CIs).

Results

The pooled results revealed a statistically significant enhancement in reproductive outcomes for infertile patients undergoing sequential embryo transfer as evidenced by elevated rates of chemical pregnancy (OR = 1.67, 95% CI = 1.23-2.27), clinical pregnancy (OR = 1.78, 95% CI = 1.43-2.21), and ongoing pregnancy (OR = 1.54, 95% CI = 1.03-2.31). Compared with cleavage-stage embryo transfer, sequential transfer yielded superior outcomes in terms of chemical pregnancy rate (OR = 2.08, 95% CI = 1.35-3.19) and clinical pregnancy rate (OR = 1.78, 95% CI = 1.37-2.31). Furthermore, among the repeated implantation failure (RIF) cohort, sequential embryo transfer surpassed blastocyst-stage transfer, delivering a heightened chemical pregnancy rate (OR = 1.66, 95% CI = 1.19-2.53) and clinical pregnancy rate (OR = 1.65, 95% CI = 1.19-2.27).

Conclusion

Our meta-analysis indicates that sequential transfer may enhance clinical pregnancy rate in a small subgroup of well-selected women. While promising, further evidence from prospective studies is needed.

Sequential embryo transfer versus double cleavage-stage embryo or double blastocyst transfer in patients with recurrent implantation failure with frozen-thawed embryo transfer cycles: a cohort study

Background

Recurrent implantation failure (RIF) is more common among patients receiving assisted reproductive treatment. Many efforts have been made to increase the incidence of clinical pregnancy among patients with RIF. The effect of the sequential transfer procedure, a two-step interval transfer of a cleavage-stage embryo followed by a blastocyst in one transfer cycle, on the clinical outcomes of RIF patients remains controversial.

Methods

In total, 1774 frozen-thawed embryo transfer (FET) cycles in RIF patients were included. Of these cycles, 302 were sequential embryo transfer (ET) cycles, 979 were double day 3 cleavage-stage ET cycles, and 493 were double blastocyst ET cycles. The primary outcomes were the rates of implantation, clinical pregnancy and multiple pregnancy, and the secondary outcomes were the rates of hCG positive, early miscarriage and ectopic pregnancy.

Results

The implantation, hCG positive, and clinical pregnancy rates in the sequential ET group (32.1%, 58.9%, 50.7%) were significantly higher than those in the day 3 cleavage-stage ET group (24.9%, 46.5%, 40.4%) and were similar to those in the blastocyst transfer group (30.1%, 56.4%, 47.1%). The early miscarriage rate in the blastocyst transfer group was significantly higher than that in the cleavage-stage ET group (17.2% vs. 8.1%, P <0.05), while the ectopic pregnancy rate in the blastocyst transfer group was significantly lower than that in the cleavage-stage ET group (0.4% vs. 3.0%, P <0.05). The multiple pregnancy rate in the sequential ET group was significantly lower than that in the cleavage-stage ET group (17.0% vs. 25.5%, P <0.05) and the blastocyst transfer group (17.0% vs. 27.6%, P <0.05). When cycles of blastocyst culture failure were excluded, the clinical pregnancy rate was significantly higher (55.7% vs. 47.1%, P <0.05), and the early miscarriage rate and multiple pregnancy rate were significantly lower (8.5% vs. 17.2%, 17.7% vs. 27.6%; P <0.05, respectively) in the sequential ET group than in the double blastocyst ET group.

Conclusions

Sequential embryo transfer in FET cycles could improve the clinical outcomes of patients with RIF.

The efficacy of sequential day 3 embryo and blastocyst transfer in patients with repeated implantation failure

OBJECTIVE

To evaluate the efficacy of sequential transfer that one cleavage-stage embryo on day 3 and one blastocyst on day 5 are sequentially transferred in the same treatment cycle over conventional day 3 embryo transfer and blastocyst transfer in patients with repeated implantation failure (RIF).

STUDY DESIGN

2836 frozen embryo transfer (FET) cycles in patients with RIF were divided into three groups according to female age: <35, 35-39 and >39 years old groups, and four groups depending on the number and period of embryo transferred: two day 3 embryo, two blastocyst, single blastocyst and sequential transfer groups; Pregnancy outcomes including implantation rate (IR), clinical pregnancy rate (CPR), abortion rate (AR), ectopic pregnancy rate (EPR), multiple pregnancy rate (MPR), live birth rate (LBR) and neonatal characteristics from all the groups were assessed.

RESULTS

Sequential transfer caused a significant increase in the IR, CPR and LBR over two day 3 embryo transfer and did not improve the IR, CPR and LBR over two blastocyst transfer in patients with RIF. Sequential transfer had higher CPR, MPR and LBR and lower IR than single blastocyst transfer. No significant differences were present in neonatal characteristics among the transfer protocol groups. Singleton group had a higher average gestational age and birthweight as well as a lower cesarean section rate, preterm labor rate and low birthweight rate than twin group. Additionally, the AR had no significant difference and the EPR of blastocyst transfer was low.

CONCLUSIONS

Sequential transfer was not an effective method to improve IR in patients with RIF, and blastocyst transfer with higher IR was suggested. Single blastocyst transfer could serve as an effective transfer protocol to reduce MPR.

Comparing the effect of sequential embryo transfer versus double blastocyst embryo transfer on pregnancy outcomes in intracytoplasmic sperm injection (ICSI) cycles in patients with repeated implantation failure: A randomized controlled trial

OBJECTIVE

Recurrent implantation failure (RIF) is the main challenge in assisted reproductive technology (ART) practice. Sequential embryo transfer, in which both, cleavage-stage embryo on day 3 and blastocyst on day 5, are sequentially transferred in the same cycle, has been suggested for increasing embryo implantation in RIF patients. The aim of the present study was to compare the effect of sequential embryo transfer versus double blastocyst embryo transfer on pregnancy outcomes in intracytoplasmic sperm injection (ICSI)/frozen embryo transfer (FET) cycles in RIF patients.

MATERIALS AND METHODS

This prospective study was enrolled 224 RIF patients undergoing ICSI/FET cycles and randomly divided to sequential and control groups. In sequential group, embryo transfer was conducted on day 3 (cleavage stage) and day 5 (blastocyst stage). In control group, two top-quality blastocysts were transferred on day 5.

RESULTS

Two hundred and two couples accomplished the trial, and their data were analyzed. Results demonstrated that sequential embryo transfer on day 3 and day 5 compared to double blastocyst transfer on day 5 significantly increased implantation rate, clinical pregnancy rate and ongoing pregnancy rate in RIF patients (p-value = 0.0142, p-value = 0.0154, p-value = 0.0201, respectively). However, there were no significant differences in terms of chemical pregnancy rate, multiple pregnancy rate, miscarriage rate and ectopic pregnancy rate in the studied groups.

CONCLUSION

Sequential embryo transfer is associated with improved pregnancy outcomes in RIF patients. Further prospective studies with larger sample sizes are required to validate these results.

Effects of sequential cleavage and blastocyst embryo transfer on pregnancy outcomes in patients with poor ovarian response

The management of patients with poor ovarian response (POR) remains a major challenge for fertility specialists in in vitro fertilization-embryo transfer (IVF-ET). In this retrospective cohort study, we aimed to evaluate the clinical effect of sequential transfer on pregnancy outcomes in patients with POR. A total of 3579 POR patients who underwent the first frozen embryo transfer (FET) cycle were enrolled from January 2018 to April 2021. The patients were divided into three groups according to the embryo transfer (ET) strategy adopted: a study group that included POR patients in whom a cleavage-stage embryo (day 3) and a blastocyst (day 5/6) were transferred (sequential transfer group), and two control groups in whom two cleavage-stage embryos (D3-dET group) or two blastocysts (D5/6-dET group) were transferred. The study group was matched with the control groups at a ratio of 1:4 by propensity score matching (PSM). The main pregnancy outcomes measured were the live birth rate and multiple pregnancy rate. After PSM, the live birth rate in the sequential transfer group was significantly higher than that in the D3-dET group (44.2% vs. 34.3%, P = 0.019), and was similar to that in the D5/6-dET group (44.2% vs. 45.3%; P = 0.90). In addition, there was no increase in the risk of multiple pregnancy among POR patients undergoing sequential transfer compared with both D3-dET (26.7% vs. 25.6%, P = 0.85) and D5/6-dET (26.7% vs. 28.4%, P = 0.97) groups. These findings imply that sequential transfer is an effective option for POR patients and could be utilized after careful consideration.

Recurrent implantation failure: A comprehensive summary from etiology to treatment

Implantation is the first step in human reproduction. Successful implantation depends on the crosstalk between embryo and endometrium. Recurrent implantation failure (RIF) is a clinical phenomenon characterized by a lack of implantation after the transfer of several embryos and disturbs approximately 10% couples undergoing in vitro fertilization and embryo transfer. Despite increasing literature on RIF, there is still no widely accepted definition or standard protocol for the diagnosis and treatment of RIF. Progress in predicting and preventing RIF has been hampered by a lack of widely accepted definitions. Most couples with RIF can become pregnant after clinical intervention. The prognosis for couples with RIF is related to maternal age. RIF can be caused by immunology, thrombophilias, endometrial receptivity, microbiome, anatomical abnormalities, male factors, and embryo aneuploidy. It is important to determine the most possible etiologies, and individualized treatment aimed at the primary cause seems to be an effective method for increasing the implantation rate. Couples with RIF require psychological support and appropriate clinical intervention. Further studies are required to evaluate diagnostic method and he effectiveness of each therapy, and guide clinical treatment.

The outcomes of sequential embryo transfer in patients undergoing in vitro fertilization with frozen-thawed embryos: A retrospective study

AIM

To explore whether sequential embryo transfer benefits patients with repeated implantation failure (RIF) undergoing frozen-thawed embryo transfer (FET) cycles.

METHODS

We included 311 patients with a history of RIF in this retrospective study. We did sequential transfers with a cleavage embryo on day 3 and a blastocyst on day 5 in 77 patients; blastocyst transfers with two blastocysts on day 5 in 80 patients; and cleavage embryo transfers with two cleavage embryos on day 3 in 154 patients. We compared clinical outcomes between the three groups.

RESULTS

The clinical pregnancy rate was comparable between the blastocyst transfer group (48.8%), the sequential transfer group(48.1%) and the cleavage embryo transfer group (48.1%). There was no statistically significant difference found (p > 0.05). The ongoing pregnancy and multipregnancy rates were also comparable between the three groups (p > 0.05). The early miscarriage rate was significantly higher in the sequential transfer group (32.4%) compared with the blastocyst group (12.8%) and the cleavage embryo group (12.2%) (p < 0.05). However, after adjusting for confounders, there was no significant difference in early miscarriage rates in the sequential transfer group compared with the blastocyst group (odds ratio [OR], 2.97; 95% confidence interval [CI], 0.85-9.24; p = 0.07) and the cleavage embryo group (OR, 3.03; 95% CI, 0.94-8.06; p = 0.08).

CONCLUSIONS

Sequential embryo transfer failed to improve clinical outcomes for patients with RIF.