In Vitro Fertilization-Embryo Transfer (IVF-ET)
In vitro fertilization (IVF) is one of the most well-known forms of assisted reproductive technologies where the eggs are retrieved by ultrasound guidance and fertilized by sperm in a laboratory dish. Eventually, the embryo is transferred back into the uterus. This treatment was originally designed to help women with blocked fallopian tubes be able to conceive, however it has become a useful treatment modality for a number of other indications.
In a natural menstrual cycle, only one follicle continues to develop and contains a maturing egg in preparation for ovulation. During ovarian stimulation, injectable medications are administered daily in order to help stimulate the development and growth of multiple follicles. During this process, serial monitoring is performed through blood draws and ultrasounds in order to ensure you are responding to your medical protocol. Sometimes, medication doses must be adjusted to accommodate the rate of follicular growth. When the ultrasound and blood work suggests that the follicles have appropriately matured, a trigger shot with human Chorionic Gonadotropin (hCG) or a gonadotropin releasing hormone (GNRH) agonist is administered to push the eggs into their final stage of maturation.
The egg retrieval is scheduled for 35-36 hours after the trigger shot. Anyone undergoing a retrieval must be fasting to receive anesthesia, which will include conscious sedation. The procedure itself consists of ultrasound guided aspiration of the eggs from each follicle. The eggs are suctioned into a test tube containing medium which is transferred to the embryologist. During this time, the male partner must collect a sperm specimen (2-3 days abstinence) or thawed from a donor sample. Unless there is male factor infertility or you are opting for preimplantation genetic testing (PGT) of the embryos, conventional IVF is recommended. This means that the eggs and sperm are placed in a dish and incubated for 18-20 hours to allow fertilization to occur naturally. Alternatively, a technique called IntraCytoplasmic Sperm Injection (ICSI) can be performed by the embryologist, whereby selected sperm is injected into the egg, bypassing the need for sperm to penetrate the outer shell of the egg. When normal fertilization occurs, two pronuclei are observed (the nucleus of the sperm and egg, each containing a single copy of each of your chromosomes) under the microscope.
The incubation process of the fertilized egg/developing embryo is termed embryo culture. Normally, a number of important nutrients secreted by the fallopian tubes and uterus help the fertilized egg to divide and develop into an embryo. In previous years, embryos were cultured until post-fertilization day 2-3, where cleavage-stage embryos (morula) were transferred back into the uterus. The day of retrieval is considered day 0. Now, with more reliable culture media, extended culture to day 5-6 is a more reliable test of viability and can help us measure embryo quality, based on its morphology. The greatest benefit of extended culture, is the increased implantation rate with a Day 5/6 blastocyst compared to a morula.
At this point in time, embryo biopsy is performed if doing PGT or collapsed and frozen for later transfer. At IVF Phoenix™, we mainly have opted for frozen embryo transfers, however the decision to transfer a fresh vs. frozen embryo will differ based on your specific clinical picture. You will be contacted with updates throughout this process to provide you with a fertilization report, and progression of your embryos to blastocyst stage.
As mentioned above, the embryo transfer may involve a fresh or frozen embryo. In a fresh embryo transfer, you will return 5-6 days following your retrieval, and any remaining embryos are flash frozen and stored in a nitrogen tank for future use. In a frozen embryo transfer, all embryos are frozen on day 5-7 and you will return to the office at your next cycle to begin preparation of your uterine lining to prepare it for transfer. Depending on your situation and inflammation markers, this may require additional preparation before we recommend moving to a programmed FET cycle vs a modified natural cycle. Once the consistency and thickness of your lining is optimal, your embryo transfer is scheduled and the healthiest appearing embryo (or euploid embryo if PGT tested) is thawed and prepared for transfer.
The day of your embryo transfer, you will arrive to the clinic with a full bladder. A speculum is placed into your vagina, your cervix is cleared of any mucus and an ultrasound is used to help guide entry of the catheter containing the embryo close to the top of the uterus where the embryo is gently placed. The catheter is checked under the microscope by the embryologist to confirm correct placement of the embryo. This is where the waiting begins! You will return 5 days later for a blood draw to measure the pregnancy hormone hCG and progesterone. Then 11 days later after embryo transfer.
Embryo Transfer Guidelines, elective Single Embryo Transfer (eSET)
The ultimate goal of IVF is to maximize your chance of pregnancy, while minimizing your risk of multiple gestation (twins, triplets or higher order pregnancy). This means, the large majority of patients will only have one embryo transferred at a time. With improved embryologic techniques in the lab, pregnancy rates are significantly higher after blastocyst transfer. The primary reason for wanting lower rates of multiple gestations is the significantly increased rates of pregnancy related complications including miscarriage, premature delivery, long term disabilities in the child, gestational hypertension, gestational diabetes, preeclampsia, etc. Per ASRM guidelines, in patients >37 years of age who did not do PGT, or those at any age without a favorable prognosis, an additional embryo may be transferred. This decision will be made based on your individual clinical scenario.
Following your embryo transfer, best rest (is not recommended, as this has been shown to reduce pregnancy rates. You can continue to live life as you normally do with light exercise, intercourse, and well balanced nutrition. The only lifestyle change that is absolutely necessary, is continued supplementation with specific recommendations and your hormonal stimulation protocol!
