Difficult Embryo Transfers during ART: Anticipating Them by Highlighting Female Risk Factors

Research Article

Austin J Reprod Med Infertil. 2024; 10(1): 1063.

Difficult Embryo Transfers during ART: Anticipating Them by Highlighting Female Risk Factors

Lemée J1; Klein J-Ph1; Tuffier S3; Ghazi M1; Aknin I1; Chauleur C1; Raia-Barjat T2; Mery L1*

¹Department of Reproductive Medicine, University Hospital of Saint-Etienne, Université de Lyon, France

²Department of Gynaecology and Obstetrics, University Hospital of Saint-Etienne, Université de Lyon, France

³University Hospital of Rennes, Université de Rennes, France

*Corresponding author: Lionel Mery Department of Reproductive Medicine, University Hospital of Saint-Etienne 42000 Saint Etienne, France. Tel: +33-4-77 82 83 07; Fax: +33-4-77 82 89 54 Email: lionel.mery@chu-st-etienne.fr

Received: December 09, 2023 Accepted: January 05, 2024 Published: January 12, 2024

Abstract

Background: Difficult embryo transfer during in vitro fertilization is responsible for low pregnancy and live birth rates. This study aims to identify possible female risk factors to anticipate a difficult embryo transfer.

Methods: A retrospective, case-control, monocentric study was conducted at the Saint-Etienne University Hospital from January 2014 to December 2020. Cases were defined as couples who had a first difficult embryo transfer during a fresh cycle; controls were randomly selected couples without history of difficult transfer. An easy transfer is defined when it is smooth and atraumatic, and difficult if greater resistance occurs, which requires the use of a firm catheter and/or a pozzi tenaculum forceps.

Patient’s data included epidemiological characteristics, cause of infertility, gestity, number of caesarean sections, surgical antecedent, uterine malformation; biological data: number of oocytes retained, number of embryos transferred, quality of the embryos transferred… Data were studied with univariate and multivariate analysis.

Results: Our study population consists of 230 cases and 690 controls. Endometriosis (OR: 2.35), tubal infertility (OR: 1.60) and the presence of a uterine malformation (OR: 5.37) were associated with an increased risk of difficult fresh embryo transfer in the multivariate analysis.

Conclusion: This study identified female risk factors that could be anticipated. A prospective study may be carried out to validate these data and to verify whether corrective measures are effective in improving clinical pregnancy and live birth outcomes.

Keywords: IVF; Embryo transfer; Risk factors; Endometriosis; Tubal infertility

Abbreviations: ART: Assisted reproductive Technologie; IVF: In Vitro fertilization; cIVF: Conventional In Vitro Fertilization; ICSI: Intracytoplasmic Sperm Injection; CPR: Clinical Pregnancy Rate ; LBR: Live Birth Rate; GnRH: Gonadotropin-Releasing; FSH: Hormone Follicle Stimulating Hormone; HCG: Human Chorionic Gonadotropin; BLEFCO: Biologistes des Laboratoires de L’étude de la Fécondation et de la Conservation de L’oeuf; KPI: Key Performance Indicator

Introduction

Embryo transfer is the crucial last step in an In Vitro fertilization (IVF) cycle. Despite the apparent simplicity of embryo transfer, difficult transfers are frequent and have been shown to significantly decrease the pregnancy rate [1-3]. According to the patient’s age, the type of treatment - conventional In Vitro Fertilization (cIVF) and Intracytoplasmic Sperm Injection (ICSI) - the number of transferred embryos, the difficulty of embryo transfer is an independent factor for predicting pregnancy [4]. This led to a recommendation in 2010, issued by the Evidence Based Guideline to ensure that the transfer goes as smoothly as possible. In 2015, the American Society for Reproductive Medicine wrote a guideline based on a review of the literature on the way embryo transfer should be performed. They recommend the use of abdominal ultrasound guidance, removal of cervical mucus, use of a flexible transfer catheter, placement of the embryo in the upper or middle part of the uterus, more than 1 cm from the fundus and immediate ambulation after completion of the transfer procedure [5].

Even though all these recommendations are followed, there are still difficult cases for embryo transfer we are currently unable to predict. Anticipating them would make it possible to implement corrections upstream of the transfer, make the transfer easier than expected and finally have the best pregnancy outcome. We know that there are anatomical causes such as tortuosity of the cervical canal or pronounced anteversion of the uterus [6], but many other factors could still influence the quality of the transfer and, to our knowledge, have not yet been studied, such as the patients’ surgical and gynaecological history and the causes of infertility.

This study aims to identify risk factors (among women predisposition) for difficult embryo transfers that could be highlighted before the first transfer attempt.

Materials and Methods

Study Design and Population

In the field of public health, a retrospective case-control study design is the most valuable type of study to identify risk factors. That is why this type of study was purchased.

A retrospective case-control study was conducted at the University Hospital of Saint-Etienne. The study included all patients undergoing Assisted Reproductive Technology (ART) with fresh embryo transfer following conventional In Vitro Fertilization (cIVF) and Intracytoplasmic Sperm Injection (ICSI) between January 2014 and December 2020. For each transfer, the quality of the transfer and pregnancy occurrences were collected. Transfers without mention of the quality were excluded.

Evaluation of the Transfer Quality

At the fertility center of Saint-Etienne, the transfers are classified into three categories: easy noted as A, correct noted as B and difficult noted as C. An easy transfer (A) is defined when it is smooth and atraumatic, correct (B) when a slight difficulty in passing the cervix occurs or when the flush is not seen with ultrasound. Embryo transfer is considered difficult (C) if greater resistance occurs, which requires the use of a firm catheter and/or a pozzi tenaculum forceps.

Cases were defined as patients who had a difficult fresh embryo transfer (C). If the couple had multiple difficult fresh embryo transfers, only the data at the time of the first difficult transfer were used to assess the risk factors for difficult transfers. Controls were defined as patients who had had an easy fresh embryo transfer (A) and had never had any fresh difficult transfer (C). They were selected by simple randomization; 3 controls were selected for 1 case.

The transfer is always performed by two gynaecologists: one performs the transfer itself, and the other guides the patient by performing an ultrasound. The gynaecologist performing the transfer classified it as easy (A), correct (B), or difficult (C), as described earlier.

We performed a preliminary analysis of our results for our Key Performance Indicator that determine Clinical Pregnancy Rate (CPR) and Live Birth Rate (LBR) for each group of transfer (A/B/C). A total of 3704 embryo transfers were analysed, of which 2392 (64.6%) were easy, 1025 (27.7%) were correct, and 287 (7.7%) were difficult. The characteristics at the time of the transfers are listed in Table 1. A difficult transfer (C) was associated with low CPR (26.8% vs 39.9% for an A transfer p=0.001) and LBR (21.6% vs 31.1% for an A transfer p<0.001) (Table 1). The results of this preliminary analysis concur with the literature [1-3,7,8].