Answer:

An embryo assessed as "beautiful" exhibits good morphology when observed under a microscope in an in vitro fertilization laboratory. The evaluation criteria include factors such as correct division speed for its stage, uniform cell size, minimal or no cytoplasmic fragments, and a clear embryonic structure.

Your day 5 embryo, labeled 4AA, represents the highest score for a day 5 embryo according to the international Gardner classification system. The number 4 indicates the embryo has reached the well-expanded blastocyst stage, with a sufficiently dilated blastocoel and a thinning zona pellucida, ready for hatching and implantation. The two letters A reflect the excellent morphology of both the inner cell mass (ICM), which will develop into the fetus, and the trophectoderm (TE) layer, which will form the placenta. These embryos typically have uniform, tightly connected cells and a stable structure, often prioritized for transfer or cryopreservation due to their high implantation potential.

However, the concept of a "beautiful" embryo only reflects certain external characteristics, such as division speed and the morphology of embryonic cell groups. It does not fully reflect the embryo's genetic quality or inherent nature. Therefore, these factors alone are not sufficient to guarantee that the embryo will implant and develop.

The time-lapse embryo culture system with integrated artificial intelligence (AI) continuously monitors embryos. *Photo: IVF Tam Anh*

If a "beautiful" embryo still fails to implant, it may relate to two main factors: the embryo's genetic quality and the uterus's receptivity. Even morphologically good embryos can carry chromosomal abnormalities due to errors during embryo formation. These embryos often fail to implant or cease development very early.

Furthermore, the uterine environment plays a crucial role as it is where the embryo attaches and develops. Abnormalities such as endometrial polyps, submucosal fibroids, uterine adhesions, uterine malformations, chronic endometritis, or endometriosis can also hinder the implantation process.

Certain medical conditions, including thyroid disorders, antiphospholipid syndrome, coagulation disorders, or embryo transfer outside the "implantation window," also reduce the chances of pregnancy. Maternal age, egg quality, endocrine disorders, prolonged stress, insomnia, or underlying medical conditions can affect embryo transfer outcomes.

If embryo transfer fails two or more times, a specialized examination is necessary for a doctor to identify the cause and devise an appropriate treatment plan. At the Assisted Reproductive Technology Center, Tam Anh General Hospital, TP HCM, doctors evaluate both the wife's and husband's reproductive health simultaneously to create a suitable treatment protocol.

Preimplantation genetic screening techniques, such as PGT-A for chromosomal abnormalities, PGT-M for single gene diseases, and PGT-SR for structural chromosomal abnormalities, help select embryos with better developmental potential, reducing the risk of implantation failure and early miscarriage.

Time-lapse embryo culture technology increases the rate of culturing embryos to the day 5 stage. Embryologists comprehensively observe and assess the embryo's development. Artificial intelligence (AI) software scores embryo quality, selecting the embryo with the highest predicted pregnancy rate for uterine transfer.

For patients with a history of failed embryo transfers, doctors perform uterine cavity assessments, including hysterosalpingography (HSG), saline infusion sonography (SIS), and hysteroscopy, to detect abnormalities such as polyps, submucosal fibroids, uterine adhesions, or chronic endometritis, thereby optimizing the treatment protocol and increasing the pregnancy rate.

Master, Doctor, Level I Specialist Nguyen Thi Bich Phuong

Assisted Reproductive Technology Center

Tam Anh General Hospital, TP HCM