Analysis of endometrial thickness patterns and pregnancy outcomes considering 12,991 fresh IVF cycles

When the Embryo Meets the Endometrium: Identifying the Features Required for Successful Embryo Implantation

Evaluation of the optimal number of embryos, their quality, and the precise timing for transfer are critical determinants in reproductive success, although still remaining one of the main challenges in assisted reproduction technologies (ART). Indeed, the success of in vitro fertilization (IVF) treatments relies on a multitude of events and factors involving both the endometrium and the embryo. Despite concerted efforts on both fronts, the overall success rates of IVF techniques continue to range between 25% and 30%. The role of the endometrium in implantation has been recently recognized, leading to the hypothesis that both the "soil" and the "seed" play a central role in a successful pregnancy. In this respect, identification of the molecular signature of endometrial receptivity together with the selection of the best embryo for transfer become crucial in ART. Currently, efforts have been made to develop accurate, predictive, and personalized tests to identify the window of implantation and the best quality embryo. However, the value of these tests is still debated, as conflicting results are reported in the literature. The purpose of this review is to summarize and critically report the available criteria to optimize the success of embryo transfer and to better understand current limitations and potential areas for improvement.

Correlation between preoperative three-dimensional transvaginal ultrasound and postoperative pregnancy outcomes after hysteroscopic adhesiolysis

OBJECTIVES

Uterine adhesion is mainly caused by endometrial injury, leading to poor postoperative pregnancy outcome. Therefore, preoperative evaluation on uterine cavity, especially endometrial condition, is very necessary. This study aims to explore the correlation between preoperative three-dimensional transvaginal ultrasound (3D-TVS) imaging characteristics and postoperative pregnancy outcomes after hysteroscopic adhesiolysis (HA).

METHODS

A total of 401 patients, who underwent HA surgery from February 22, 2018 to October 31, 2018 at the Third Xiangya Hospital of Central South University or Changsha Jiangwan Hospital, were enrolled, and we collected data regarding the preoperative 3D-TVS imaging characteristics and followed up their postoperative pregnancy outcomes. Correlation analysis and univariate and multivariate logistic regression analysis were performed between imaging features and pregnancy outcomes (live and non-live birth outcomes) in patients with intrauterine adhesion.

RESULTS

The results of correlation analysis showed that endometrial thickness, endometrial echo, visible tubal openings, endometrial blood flow, intercornual distance, and endometrial peristalsis were correlated with the live birth rate (all P<0.05). Logistic regression analysis revealed that in the HA patients with the live birth, the endometrial thickness was thicker (P<0.001), endometrial echo was more homogeneous (P<0.001), the number of tubal openings was more (P<0.001), the intercornual distance was wider (P<0.05), the endometrial blood flow, and irregular cases of endometrial peristaltic waves were more and cases of deficiency were fewer (both P<0.01) than those in the non-live birth group.

CONCLUSIONS

Preoperative 3D-TVS imaging performance is closely related to pregnancy outcomes of HA patients, and preoperative 3D-TVS can be used to predict pregnancy outcomes after HA.

Impact of the duration of oestradiol treatment on live birth rate in Hormonal Replacement Therapy cycle before frozen blastocyst transfer

Although the duration of progesterone administration in Hormonal Replacement Therapy (HRT) cycles before frozen embryo transfer is standardized, the optimal duration of oestrogen treatment remains controversial. In this monocentric retrospective study conducted in all single frozen blastocyst transfer (FBT) performed with HRT between January 2016 and July 2019, we evaluated the association between the duration of oestradiol treatment before FBT and live birth rate (LBR) in HRT cycles. Cycles were gathered in 3 groups according to quartiles of duration of oestrogen treatment. LBR was compared across the 3 groups and multivariate analysis was performed. We included 2235 single FBT cycles; 507, 1257 and 471 with E2 treatment below 23 days, 23-30 days (reference) and more than 30 days respectively. After multivariate analysis and adjustment, no significant difference in LBR was found between below 23 or more than 30 days and reference groups (OR = 0.93 [0.68-1.27] and OR = 1.29 [0.88-1.89] respectively). Complementary sensitivity analysis led to a non-significant adjusted OR = 1.66 [IC 0.9-3.1]. In conclusion, our study showed that the duration of E2 treatment in HRT cycles before FBT is not associated with LBR.

Does increasing estrogen dose during frozen embryo transfer affect pregnancy rate?

OBJECTIVE

To assess the effect of increasing estrogen doses during hormone therapy frozen embryo transfer (HT-FET) cycles on endometrial thickness and success rates compared to patients who received fixed estrogen dose.

MATERIALS AND METHODS

A retrospective study from a university-based fertility clinic during the years 2008-2021. We compared two groups: the fixed-dose group (i.e., received 6 mg estradiol dose daily until embryo transfer) and the increased-dose group (i.e., the initial estradiol dose was 6 mg daily, and was increased during the cycle).

PRIMARY OUTCOME

clinical pregnancy rate.

RESULTS

The study included 5452 cycles of HT-FET: 4774 cycles in the fixed-dose group and 678 cycles in the increased-dose group. Ultrasound scan on days 2-3 of the cycle showed endometrial thickness slightly different between the two groups (4.2 mm in the fixed-dose and 4.0 mm in the increased-dose group, P = 0.003). The total estrogen dose was higher, and the treatment duration was longer in the increased than the fixed-dose group (122 mg vs. 66 mg and 17 days vs. 11 days, respectively; P < 0.001). The last ultrasound scan done before the addition of progesterone showed that the endometrial thickness was significantly thicker in the fixed than the increased-dose group (9.5 mm vs. 8.3 mm; P < 0.001). The clinical pregnancy rates were 35.8% in the increased-group vs. 34.1% in the fixed-dose group; P = 0.401.

CONCLUSIONS

The increased-dose group had thinner endometrium despite the higher doses of estrogen and longer treatment duration than the fixed-dose group. However, the pregnancy rates were similar between the two groups.