The fourth step in the IVF process is the fertilization of the egg and development of the embryo in preparation to be implanted in the uterus. The best method of fertilizing the egg will be decided by the fertility specialist. They will make their decision based on the quality and quantity of the sperm and egg cell.
Conventional Fertilization
If the sperm is very vibrant and healthy the fertility specialist can merely introduce the sperm to the egg and the sperm will naturally fertilize the egg. To do this they will wash the sperm to isolate individual sperm cells and then they will select the very best sperm. They will then introduce the sperm to the egg in a lab dish and the sperm will naturally fertilize the egg.
ICSI (Intracytoplasmic Sperm Injection)
In cases where the sperm quality is low and the sperm is weak the fertility specialist may decide to fertilize the egg via ICSI. In this procedure the fertility specialist will select one single sperm, the best quality they can isolate from the sample, and inject that sperm directly into the egg cell. This method is highly effective in cases where there is limited sperm quality and quantity to work with.
Development of the Embryo
They will usually fertilize more than one egg cell in order to give them a selection of embryos to work with. After the fertilization of the egg cell it will be monitored for progress. After about a week of growth the fertility specialist will then select the best embryo or embryos, (sometimes multiple embryos will be implanted) to be implanted. Any unused embryos can be frozen for future use or as donor embryos.
Please join us in our series A beginners introduction to IVF (In Vitro Fertilization). This was Step 4 and the rest are to follow as we explore an IVF Cycle and In Vitro Fertilization. Step 1 can be found here: Initial IVF Consultation & Preparing the Ovaries for Stimulation