Behind the Scenes of IVF: What Happens in the Lab After Egg Retrieval
In vitro fertilization (IVF) is an advanced fertility treatment involving fertilizing an egg with sperm outside of the body. While more invasive and complex than other forms of fertility care, IVF also boasts higher success rates, making it a worthwhile option for aspiring parents experiencing infertility. Although patients undergo multiple procedures during IVF, the time between egg retrieval and embryo transfer can feel like a black box. During this stage, embryologists are hard at work in the lab, fertilizing eggs and monitoring embryo development to support a healthy pregnancy.
Fertilization
After retrieval, the embryologist will fertilize the eggs with sperm from either a partner or a donor using one of two methods:
Conventional insemination: The sperm and eggs are combined in a controlled environment to fertilize.
Intracytoplasmic sperm injection (ICSI): An embryologist injects a single healthy sperm into each mature egg. Patients typically choose ICSI when the male partner has issues with sperm quantity or quality, or if previous fertilization attempts have been unsuccessful.
Embryo Development
Over the next five to six days, the embryologist will closely monitor the embryos. An embryo has to overcome significant obstacles to reach the blastocyst stage and be suitable for transfer. This stage of embryo development is ideal for implantation. On average, 50% of embryos advanced to the blastocyst stage. The remaining 50% typically fail to progress and get discarded. For example, if an embryologist fertilizes seven eggs, three or four of them will likely make it to the blastocyst stage. Embryos at the blastocyst stage can either be considered for a “fresh” transfer or frozen and stored for future use.
During this stage of embryo development, IVF patients can opt for preimplantation genetic testing (PGT). PGT involves obtaining a sample from each embryo and testing it for certain genetic diseases or the correct number of chromosomes. This testing can reduce the chances that a parent will pass on a genetic condition.
Embryo Transfer
During the embryo transfer procedure, the fertility specialist uses a long, flexible tube (catheter) with a syringe at the end of it that contains the fertilized embryo. They insert the catheter through the cervix under ultrasound guidance to place an embryo into the uterus. Within a few days of the transfer, the embryo will hopefully attach to the lining of the uterus, and the patient will become pregnant.
Frozen vs Fresh Embryo Transfer
IVF patients may undergo a frozen or fresh embryo transfer. A fresh embryo transfer is performed three to five days after egg retrieval. In a frozen embryo transfer, embryos from a previous IVF cycle or a donor are thawed and inserted into the uterus. Frozen embryo transfers can occur years after egg retrieval and fertilization.
Learn More About IVF
IVF can be a daunting process, and it’s normal for patients to have questions and concerns about the fertilization and development of their most precious genetic materials. However, understanding what goes on behind the scenes can make an IVF cycle less intimidating overall.
At Kentucky Fertility Institute, our experienced team is dedicated to providing residents of Kentucky and surrounding areas with world-class fertility care, including treatments like IVF, PGT, and more. Contact us today for more information or to schedule an appointment at our Louisville clinic.