Case Report: Breaking barriers - Pregnancy achieved by intracytoplasmic sperm injection of a zona-free oocyte

Abstract

The zona pellucida is a protective layer surrounding the oocytes and early-stage embryos. It is said to be essential for the process of fertilisation and protecting the pre-implantation embryo. Absence of zona pellucida can pose great problems during in vitro fertilisation (IVF), like impaired fertilisation, polyspermy and hindered embryo development, thus leading to a low implantation rate and unsuccessful pregnancy outcome. This case report demonstrates the successful treatment of primary infertility in a 35-year-old female with significantly low anti-Mullerian hormone (AMH) levels and limited ovarian reserve. Her husband (41 years) had oligoasthenozoospermia. The couple had been trying to conceive for two years before seeking medical assistance. Following an unsuccessful intrauterine insemination (IUI) attempt, the decision was made to pursue IVF with ovarian stimulation. Two oocytes were retrieved after ovum pickup, one of which was at the germinal vesicle (GV) stage and later degenerated, while the other was without the zona pellucida. In this case, the intracytoplasmic sperm injection (ICSI) of zona-free oocyte was chosen to prevent polyspermy, resulting in successful fertilization. The embryo progressed to the eight-cell stage and was transferred on day three. A positive beta-human chorionic gonadotropin (β-hCG) test confirmed pregnancy fourteen days later. In assisted reproductive techniques (ART), zona-free oocytes are a common occurrence, but fertilizing those oocytes is not common; they are usually considered to be of no use and rejected. In the present case, we realized that zona-free gametes are not only capable of getting fertilized and developing into good-quality embryos, but also give successful pregnancy outcomes.