In-Vitro Fertilization (IVF)
In vitro fertilization (IVF) refers to the union of egg and sperm outside the body. In a broader sense, it is an assisted reproductive technology that offers hope to individuals and couples who have otherwise been unable to conceive on their own. Since its development, millions of healthy children have been born worldwide as a result of IVF. There are five major steps in the IVF process.
In Vitro Fertilization (IVF) and Embryo Transfer
Risk of Multiple Birth
Stages Of An In Vitro Fertilization Cycle
1. Ovarian stimulation
Injections of fertility medications called gonadotropins are taken daily by the woman, which causes the growth of multiple follicles. At the same time, additional injections of medications called GnRH agonists or antagonists are also taken daily to prevent ovulation. During ovarian stimulation, progress is monitored with a series of blood tests and vaginal ultrasounds. Lastly, an injection of a hormone called ovidrel or human chorionic gonadotropin (hCG) is taken to cause final maturation of the eggs in preparation for the egg retrieval procedure. The timing of this “trigger” injection is determined by egg follicle sizes.
2. Egg retrieval and sperm collection
Approximately 36 hours following the “trigger” injection, patients will have their egg retrieval procedure. An ultrasound probe is placed in the vagina and a needle is passed through it, into the ovary. The eggs are collected from the follicles. Although there can be some discomfort, medication is given to minimize pain and the egg retrieval is generally well-tolerated. Most commonly, men will provide an ejaculated sperm sample for use, just before the egg retrieval procedure. In other situations, previously cryopreserved sperm, donor sperm or surgically retrieved sperm will be used for fertilization.
3. Fertilization and embryo culture
After a period of incubation in the lab, each egg is placed in a dish with a large number of moving sperm and fertilization is allowed to occur. If the sperm are low in number or movement, a single sperm can be selected and injected into each egg using a technique called intracytoplasmic sperm injection (ICSI). After eggs and sperm are combined, fertilization may occur. The resulting embryos are allowed to grow in the lab until ready for transfer into the uterus.
4. Embryo transfer
One or more embryos are placed into the uterus using a soft, flexible catheter or tube that is guided through the cervix by ultrasound. The discomfort of an embryo transfer procedure is similar to that of having a pap test, but with a full bladder. After the embryo transfer, following 15 minutes of rest, patients return home and are advised to rest for that day. Any good quality embryos remaining after the transfer may be cryopreserved for future use.
5. Progesterone supplementation and pregnancy test
Starting the day of the egg retrieval procedure, progesterone tablets are placed in the vagina in order to support a developing pregnancy. Occasionally, progesterone is given as an injection. A pregnancy test is performed approximately 17 days after egg retrieval. If positive, an ultrasound is performed to assess the health of the pregnancy, which is usually done two to three weeks after a positive pregnancy test.
Intracytoplasmic sperm injection (ICSI) is a technique in which a single sperm is placed into an egg. ICSI is the biggest advancement in fertility treatment since in vitro fertilization (IVF) and has allowed many men to have genetically-related children. Since ICSI requires very few sperm, it can be an effective treatment for men with severe sperm abnormalities. Typically, ICSI uses ejaculated sperm, but surgically retrieved sperm can also be used. ICSI is performed as part of an IVF cycle.
Laser Assisted Hatching: In the normal process of implantation the embryo has to break through its gel-like outer covering called the zona pellucida prior to attaching to the endometrium. Some embryos may have a tougher zona pellucida than others. It is possible to make a small opening in the zona pellucida using a laser, just before the embryo transfer. This technique is called laser assisted hatching.
Blastocyst culture is used to sustain embryo growth in the lab beyond three days. After five days in culture, embryos reach the blastocyst stage, where they have more than 80 cells surrounding a central fluid-filled cavity. This longer period of embryo culture permits an improved ability to choose the healthiest embryos for transfer and is associated with a higher pregnancy rate, while transferring fewer embryos.
Embryo Vitrification: Excess embryos may remain after your in vitro fertilization (IVF) cycle and fresh embryo transfer. These embryos may be suitable for cryopreservation or freezing. Embryo cryopreservation provides the opportunity for additional attempts at pregnancy from a single IVF cycle.
Vitrification is a specialized freezing technique whereby embryos are cryopreserved using an ultra-rapid cooling technique, turning them into a glassy solid instead of ice, and by doing so avoiding ice-crystal formation which can be very detrimental to their survival. The Ottawa Fertility Centre introduced vitrification in 2011 and has seen very good post-thaw results. Improved post-thaw survival rates of embryos means better pregnancy and live birth rates in frozen embryo transfer cycles.