Zona Pellucida Removal Resulted in a Successful Live Birth: Report on a Case with Recurrent Implantation Failure due to Embryonic Bacteria Contamination

1. Introduction The success of in vitro fertilization (IVF) relies on a series of crucial laboratory procedures, including the culture and development of embryos in a controlled environment. However, despite strict quality control, there is a risk of bacterial contamination during the embryo culture process [1]. Such contamination poses a threat to the IVF outcomes. Bacterial contamination in the IVF laboratory can arise from various sources, including air, water, equipment, and personnel [2]. It can also occur at different stages of the IVF process, such as during oocyte retrieval, sperm preparation, handling of culture dishes, or manipulation of embryos. Bacteria introduced into the culture media can proliferate rapidly, producing harmful byproducts and triggering inflammatory responses that may negatively impact embryo development. Additionally, certain bacteria may directly adhere to the embryo’s zona pellucida, compromising its integrity and reducing the chances of successful implantation.Commonly, the washing technique is employed to rescue embryos that have been contaminated. It involves the gentle removal of external contaminants from the embryo’s surface. The washing process begins by transferring the contaminated embryo to a clean petri dish containing a culture media supplemented with antibiotics or antifungal agents. Gentle swirling motions are then used to perform the washing. After that, the embryo is transferred to a fresh, uncontaminated dish with a clean culture medium. However, a study has demonstrated that washing alone is not effective in eliminating bacteria, as some still remained in the zona pellucida [3]. In a recent case report by Li R et al., a new method was proposed to rescue contaminated embryos, involving the removal of the contaminated zona pellucida using Tyrode acid [4]. It has been observed that the porous structure of the zona pellucida makes it difficult to completely eliminate microorganisms [5]. Additionally, the zona pellicida itself can prevent embryo development in later stages [6]. Therefore, removing zona pellucida is a promissing method to solve the contamination problems.In our report, we describes an alternative method using laser to remove the contaminated zona pellucida from an embryo. We present the clinical details, procedural methodology, and subsequent outcomes of this unique case, thereby shedding light on the promising prospects for assisted reproductive technologies.