In vitro fertilization (IVF) is a type of assisted reproduction that is performed in a laboratory.
Many patients believe that IVF is the most common treatment offered by reproductive endocrinologists for infertility. IVF is a major breakthrough that gives new hope to couples who otherwise could not produce genetically related children. However, most women become pregnant using less advanced technologies such as intrauterine insemination.
IVF is considered a first line treatment in selected conditions such as infertility caused by fallopian tube problems, moderate to severe male factor infertility, ovarian failure and some cases of endometriosis. It is also used after other therapies have failed.
In Vitro Fertilization Process
The ovaries must be stimulated to produce numerous eggs that can be retrieved and fertilized. Some eggs are damaged in the IVF process and enough must survive to produce an adequate number of embryos.
The female receives daily injections of follicle stimulating hormone (FSH) which stimulates the recruitment and development of multiple follicles, each containing one egg. Antagon is also given as an injection just prior to egg retrieval to prevent the body from prematurely releasing the eggs.
Patients come to our office for ultrasound monitoring and estradiol hormone level measurements while undergoing stimulation. These tests allow us to monitor follicular development and make necessary FSH dosage adjustments.
Once the physician determines that the eggs are mature, retrieval is scheduled and human chorionic gonadotropin (hCG) is administered.
The eggs are removed just prior to release into your body.
Some women cannot produce eggs that will fertilize and develop due to age, genetic disease or other factors. In these cases, an egg donor can be used. Egg donors undergo the same stimulation and retrieval process. The eggs are fertilized with the partner's sperm and the resultant embryos are transferred to the recipient mother.
On the day of retrieval the couple returns to our office. The male provides sperm by masturbation which is washed and specially prepared for exposure to the eggs. The female receives anesthesia in the minor procedure suite next door and the eggs are retrieved from the ovarian follicles using a small needle passed through the back of the vagina using ultrasound for visualization.
Fertilization and Embryo Culture
Once the eggs are retrieved they are passed to the embryologist who separates them from the follicular fluid. They are then placed in specially prepared media and combined with sperm in Petri dishes. Once fertilization occurs the embryos are kept in the incubator until the embryo transfer.
Micromanipulation procedures such as intracytoplasmic sperm injection (ICSI) are performed at this stage. When ICSI is used a single sperm is injected directly into the egg.
The embryos remain in the incubator until they mature, which is usually from 3 to 5 days.
Embryos that survive to day 5 (blastocysts) are heartier and more likely to implant and develop. Some embryos are lost during culturing so there must be enough embryos to “risk” extending the culture time to 5 days.
In many cases, couples produce more embryos than can be safely transferred back to the uterus in one cycle. These embryos can be cryopreserved for use in future non-stimulated IVF cycles. The major advantage to a non-stimulated cycle is that FSH injections are not necessary and therefore the cost is significantly less.
Some couples are at high risk for transmitting specific genetic diseases, such as Tay-Sachs. In these cases, the embryos may be screened using preimplantation genetic diagnosis (PGD) which allows us to identify embryos that carry the genetic abnormality.
The IVF nurse contacts the couple and advises when to arrive at our office for the embryo transfer. The embryos are placed in the uterus in a painless procedure using a small catheter and ultrasound for guidance.
Once inside the uterus, the embryo must “break free” of its surrounding shell and attach to the endometrial lining.
Assisted hatching involves etching a small hole in the shell prior to transferring the embryo to the uterus. It is thought that the opening makes it easier for the embryo to hatch and implant.
Assisted hatching is most often used in patients who repeatedly fail to conceive in IVF cycles, when there are poor quality embryos or in women over the age of 38.
Once the embryo is transferred, the patient is advised to rest for the next 24 hours and a pregnancy test is performed after approximately 2 weeks.