In Vitro Fertilization
In vitro fertilization (IVF) literally means fertilization "in glass" and this refers to the fact that fertilization takes place outside of the body in a dish in the laboratory. Any assisted conception procedure where fertilization takes place outside the body is a form of IVF. IVF was originally devised to overcome infertility caused by blocked or absent fallopian tubes. Today, IVF is used to treat many reproductive problems, including irregular ovulation, low sperm count and/or motility, and unexplained infertility.
In Vitro Fertilization Programs at the Reproductive Medicine Center
- An IVF on a per cycle basis (as opposed to a cost sharing program as described below) for women less than age 43.
- IVF using eggs from a known donor on a per cycle basis or from an unknown donor in a cost sharing program.
- Micro manipulation techniques including intracytoplasmic sperm injection (the injection of a single sperm into an egg to initiate fertilization) and assisted hatching in which case a hole is created in the "shell" to allow the embryo to break out and implant in the wall of the uterus.
- Culture to blastocyst stage. This is currently available as part of an ongoing study to assess the value of blastocyst transfer in reducing the risk of multiple gestations (twin, triplets, etc.) without reducing the likelihood of pregnancy.
- Fertility Cost Sharing Programs (FCSP) - Many couples are confronted with the problem of having to choose between trying IVF and adopting. The FCSP gives couples the opportunity to try three cycles of IVF for a predetermined cost, and if this does not result in a live birth most of the cost of the procedure will be refunded to help cover the cost of adoption. Learn more about the Fertility Cost Sharing Program
The IVF Process in Detail
Egg Retrieval (day 0)
Your clinical healthcare team will determine the day of egg retrieval based on the response of your ovaries to hormone injections. The retrieval of your eggs will be done in our specially designed and equipped "Procedure Room." Much like the umbilical cord connects the baby and the mother, our Procedure Room and In Vitro Fertilization Laboratory are necessarily intimately connected. This unique configuration ensures the delivery of high quality care from the time your eggs are harvested to the time you receive your embryos on the day of transfer.
During the egg retrieval procedure, test tubes are filled with the fluid and cellular content from each follicle (a cyst in your ovary containing an egg) that the doctor has targeted for aspiration. The nurse passes each test tube containing follicular contents through a window in the IVF lab to an embryologist who will then use a microscope to scan the contents of each tube to determine if one or more eggs are present. When an egg is identified, its presence is recorded on a report form, and the egg is immediately removed from the follicular fluid and placed in a test tube that contains a solution designed to keep the egg(s) safe until completion of the egg retrieval procedure. The procedure is completed when all targeted follicles have been drained of their contents. Once the eggs have been tallied and evaluated, the embryologist will inform you of the total egg number, how fertilization will be attempted, other particulars of your case that are laboratory-related, and will confirm a phone number to reach you the next morning to convey fertilization results.
While the egg retrieval procedure might be over, the work in the IVF lab has only just begun. Prior to egg retrieval, the lab personnel will have prepared special solutions to culture your eggs and embryos. In addition, a specific location for your eggs and embryos will have been reserved in one of our specially designed incubators. Thus, after all the eggs have been retrieved, the embryologist will quickly and efficiently evaluate their maturity and quality before placing them into a culture dish labeled with a unique number that is specific to you and no other person. Your eggs will remain in this dish, which will be placed in the reserved spot in one of the incubators, where they will continue to develop until later in the day when sperm and egg will be introduced to each other.
Sperm Collection (day 0 or earlier)
For most men, adequate numbers of sperm will be present in the ejaculate to ensure that there will be at least one sperm for each egg retrieved. For those men who do not have sufficient numbers of sperm in their ejaculate, an alternate approach must be taken to obtain sperm (see below, TESE). To ensure that we have an adequate quantity of sperm for IVF, 2 days of abstinence are required before producing the semen sample. However, the sperm also need to be quite fresh, so you should not abstain for longer than 7 days before the day of IVF. Sperm collection should be done in one of our special, private collection rooms at RMC. If you anticipate that you will have any trouble providing a sample on the day of the egg pick-up procedure, then we can arrange for you to collect a specimen ahead of time and have the sperm frozen. If it is necessary for you to collect the specimen at home, then we can provide you with special condoms that are not sperm-toxic so that the specimen can be collected during intercourse. If you choose to use the collection condom, then you will need to get the sample to us as quickly (less than 1 hr) as possible after the sample has been produced.
For men with no usable sperm in their ejaculate, there is the possibility of obtaining sperm directly from the testis using a testicular biopsy procedure (TESE). This procedure involves the removal of a small (pea-sized) portion from one or both of the testes by a Urologic surgeon. This procedure is typically done under local anesthesia and the only major side effect is post-operative scrotal discomfort. The pain typically subsides within a day or so. Technologists in the RMC Diagnostic Andrology Laboratory process the tissue that has been extracted. The tissue is minced into a fine slurry, evaluated for the presence of sperm, and in most instances treated with a caffeine-like chemical that stimulates sperm motion. The demonstration of motion, which reflects a functional sperm, is critically important for optimizing the potential for normal fertilization and embryo development.
Fertilization (day 0)
Before sperm can be added to eggs for fertilization, they must first be isolated from the fluid in which they are contained. The process to isolate sperm is typically done using a technique called "sperm washing." This relatively simple procedure involves placing the ejaculate over a liquid in a test tube and then spinning the tube very fast in a device called a centrifuge. After about 20 minutes of spinning, the fast swimming, more normally shaped sperm will be isolated at the bottom of the test tube. The bottom portion is retained for inseminating the eggs while the remainder is discarded. Once the washed sperm have been counted and their motion characterized, the washed sperm are kept warm until early afternoon, when the eggs and the sperm will be put together.
There are two common methods for getting sperm and eggs together. The first can be considered as more traditional, and it involves the addition of a specified number of swimming sperm to a dish containing nutritive medium and one or more eggs. This procedure is called in vitro insemination; once the eggs and sperm are mixed together in the plastic dish, they are left in an incubator overnight.
The second method for getting sperm and egg together is called IntraCytoplasmic Sperm Injection (ICSI), and it is used for cases of severe male infertility (e.g., when sperm are surgically extracted directly from the testis (TESE) or if the sperm in the ejaculate have a decreased ability to fertilize an egg without help). ICSI is a very specialized technique that requires a great deal of training and skill on the part of the embryologist. To perform the ICSI procedure, the embryologist must use a special microscope and equipment that allows for the manipulation of both egg and sperm on a microscopic level (figure 1). To put it in perspective, an egg (see Figure 1) is just one-tenth of a millimeter across (about the diameter of a hair), yet it appears huge in comparison with the injected sperm (20 times smaller than the egg) at the tip of the needle-like injecting pipette. The egg is gently held with a suction pipette (Figure 1a) while a sperm is picked up with the injection pipette, and then the injection pipette is passed through the outer shell (called the zona pellucida) and into the cytoplasm of the egg (Figure 1b), where the sperm is deposited (Figure 1c).
Figure 1 - Intracytoplasmic Sperm Injection
Fertilization Assessment (day 1)
The day after getting sperm and eggs together, the eggs are checked for signs of fertilization. Two faint spheres called pronuclei are visible in an egg after normal fertilization (Figure 2), with one pronucleus contributed by the woman and one pronucleus from the man. The pronuclei hold the DNA of the sperm and the egg, and they will subsequently combine to form the nucleus of the embryo in a process called syngamy. If an egg has more or less than two pronuclei, it is considered abnormal and it will be discarded.
Figure 2 - Fertilized, pronuclear stage oocyte
When the fertilization status of all inseminated eggs has been determined, the embryologist will call you to convey the outcome. You will be told how fertilization was attempted, how many eggs did and did not fertilize, and if there were any other unique findings. The day of your embryo transfer will also be confirmed. As part of laboratory procedure, the embryologist will record how many eggs fertilized, how many eggs did not fertilize, and any other aspects related to fertilization assessment. The normally fertilized eggs, now called zygotes, are transferred into a dish that has been prelabeled with your unique identification number, returned to the incubator, and allowed to develop until the day of your embryo transfer.
Figure 3 - Multicell embryo
Embryo Transfer (day 3)
By the day of embryo transfer the embryo(s) will typically consist of at least 6 to 10 cells (Figure 3) encased by a soft "shell" (the zona pellucida). The physician and embryologist will discuss embryological, historical, and female physical factors, including embryo number and quality, female age, and previous IVF attempts, to determine whether one, two or three embryos will be transferred to your uterus. Your desires and acceptance of risk also figure strongly in deciding how many embryos will be transferred. Any remaining good quality embryos will be "frozen" for future use if you wish.
The embryologist will pick up the embryos that have been selected for transfer using a special catheter (a very thin tube) that is designed to safely pass through the cervix and into the uterus without causing any damage. The catheter, loaded with the embryo(s), is carefully guided through the cervix by the doctor and is advanced to reach the upper middle part of the uterus where the embryos are then deposited. The front and back of the uterus are normally touching, and this holds the embryo in place. However, we will ask that you remain still for 20 minutes, after which you are instructed to return home and restrict your activity for 24 hours.
Assisted Hatching (day 3)
The growing embryo needs to hatch out of the zona pellucida on or about day 6 to implant in the lining of the uterus. The zona pellucida is a tough membrane that surrounds the egg/embryo and is analogous to a shell. For implantation to be successful an embryo must release itself from the zona shell - failure to do so will result in failed implantation. Assisted hatching (AH) is a technique used to facilitate hatching of the embryo out of the zona pellucida for subsequent implantation in the lining of the uterus. Assisted hatching is used routinely in women older than 36, couples who have failed to conceive in prior IVF attempts, or if the embryologist notes that the zona pellucida is thicker than usual.
Blastocyst Transfer (day 5)
One goal of the RMC assisted reproductive technologies program is to maintain a proactive approach for minimizing the incidence of multiple gestations resulting from IVF. One way to reduce the potential for multiple gestations is by reducing the number of embryos used for transfer, and this approach has proven to be very successful for RMC.
If you think of reproduction as a path with several milestones that must be reached (e.g., ovulation, fertilization, cleavage of the embryo, etc.), then one of the milestones for an embryo is development to the blastocyst stage. Given recent advances in the ability to culture embryos for longer periods of time, it is now possible to keep embryos in culture until they reach the blastocyst stage (day 5). By increasing the number of days the embryos are incubated, the embryos have an opportunity to develop and undergo cell division. During normal embryo development, the embryo divides into two cells, then four cells and so on until the embryo matures to the blastocyst stage. The blastocyst stage occurs just before implantation takes place. Only 20-25% of embryos will reach the blastocyst stage, but the transfer of blastocysts has been associated with very high implantation rates (45-65%). The selection of embryos for transfer with high potential for pregnancy is made easier when choosing from blastocyst stage embryos. Since the early evidence suggests that blastocyst stage embryos have a high implantation rate then fewer embryos need to be transferred and the risk for multiple pregnancies is reduced.
Whether you have your embryos transferred at Day 3 or Day 5 is your decision. Some patients prefer to have the embryos put back earlier rather than risk there not being any still developing on Day 5, while others would prefer not to have the transfer if the embryos do not survive to Day 5.
Human Embryo Cryopreservation
For many couples, there will be a surplus of embryos (embryos that were not transferred) after an IVF procedure. Depending on their quality, these surplus embryos can be frozen and stored until a time you chose to use them. For some women, there might be a medical reason (e.g., hyperstimulation) to forego fresh embryo transfer and to freeze all the embryos that are of adequate quality. The techniques and equipment we use at the Reproductive Medicine Center to freeze and thaw human embryos are also used by other successful IVF centers around the world.
In order for an embryo to successfully survive freezing and thawing it must be dehydrated during the freezing phase and then rehydrated during the thaw phase. The movement of water in and out of the embryo can be stressful and in some cases can cause damage to one or more of the cells in the embryo or even death of the embryo. However, the methods we currently use are very effective and embryo death occurs infrequently. Also important in terms of embryo survival is the quality of the embryo at the time it was frozen. In general embryos of good quality will tolerate the freeze/thaw process whereas poor quality embryos are more susceptible to damage. It is because of the latter issue that we typically only freeze embryos of average or better quality.
The embryo transfer procedure for thawed embryos is the same as for non-cryopreserved IVF embryos.
