IVF Made Easy:
In a nutshell, IVF is the process of collecting eggs and fertilizing them in the laboratory.The resulting embryos are culture for 3-5 days before they are transferred into the uterus or frozen for future use.
IVF is significantly more successful than natural fertility due to the high number of eggs produced in one cycle and the minimal number of sperm needed to fertilize them.
There are basic 5 steps in IVF: Stimulation of the ovaries, egg retrieval, fertilization, embryo culture, and embryo transfer. Only the first step, ovarian stimulation, changes with the type of patients- the rest of the IVF process stays the same. Let’s review each step:
1. Ovarian Stimulation:
Although a woman can produce 10-20 eggs every cycle, only one of them is allowed to grow and ovulate in a natural cycle. To improve the chance of success with IVF, medications are used to directly stimulate the ovaries to override this selective tendency in order to allow more eggs to reach maturity. These stimulating medications contain FSH (follicle stimulating hormone) to make multiple follicles to grow.
However, the body has its own defense against multiple pregnancies. When facing multiple growing follicles, the brain and pituitary can trigger ovulation of the largest follicle by releasing LH (luteinizing hormone), and once the first egg has been released, all the remaining follicles will stop growing.
Thus, we must use another type of medications to prevent the interference of Mother Nature. These medications (Lupron or an GnRH antogonist) act on the brain and pituitary to prevent the release of LH to cause premature ovulation. Once the risk of premature ovulation has been eliminated, ovarian stimulation can proceed until the follicles become mature and ready for egg retrieval.
Once the pituitary can no longer interfere with the growth of the follicles, stimulation of the ovaries can begin with close monitoring of the ovaries by ultrasound and hormone levels. This is where there can be great variation as patients can benefit from different stimulation protocols depending on their unique situations.
Choosing the correct stimulation protocol is one of the most important decisions in IVF planning. At IVFMD, we take great care in assessing every patient’s situation when designing the ovarian stimulation protocol. The reserve of the ovaries, as determined by the AMH level and the antral follicle count, plays a critical role in helping us deciding the stimulation protocol. Patients who have normal egg reserve can use the regular IVF protocols, whereas patients with low egg reserve can benefit from one of the aggressive protocols.
2. Egg Retrieval
After about 10 days of ovarian stimulation with injectable medications, most of the follicles should mature size. An injection called HCG (Human Chorionic Gonadotropin) is administered to induce the final maturation of the eggs.
About 36 hours after HCG triggering, the eggs are aspirated through the vagina under ultrasound guidance in the office. The patient sleeps for about 20 minutes under deep IV sedation given by an anesthesiologist. Once the retrieval is completed, she would wake up almost immediately after the IV medications are discontinued. Most women have mild pelvic soreness and cramping after the procedure, but this is self limited, resolving within a couple of hours after the retrieval.
For safety reasons, our anesthesiologists require patients to be at body mass index (BMI) of 38 or lower. High body mass can allow accumulation of the anesthetic Propofol that in high dose can suppress respiration.
Once the eggs are collected, identified and prepared, they are ready for fertilization in the lab.
After their aspiration, the eggs are isolated under the microscope and are fertilized the same day. We have two methods of fertilization, IVF and ICSI. In conventional IVF each egg is incubated overnight in a droplet of special media with 70,000 motile sperm. Nature will determine the best sperm to fertilize the egg.
In cases of low sperm concentration or motility, ICSI (Intracytoplasmic Sperm Injection) is required to ensure fertilization. Under the microscope, one normal appearing sperm is chosen and injected directly into the egg.
The day after the eggs are inseminated or sperm injected, they are checked for sign of fertilization. An egg is considered to fertilize normally when 2 pronuclei (one from each parent) are seen. The average rate of normal fertilization by IVF or ICSI is 70%. The day after the retrieval we check for fertilization. Typically, about 70% of the mature eggs are fertilized.
4. Embryo Culture
The fertilized eggs are cultured for 5 days, which is the same number of days an embryo takes to travel from the distal end of the tube into the uterus during natural conception. The embryos are cultured in very special conditions, where the temperature, gases and pH are precisely controlled. In order to minimize fluctuations in the air and temperature of the incubator, we check the embryos on day 1, 3, and 5, counting day 1 as the day after retrieval. Patients are informed of the progress of their embryos after each check.
During this period, the woman takes progesterone to prepare her uterine lining for the embryo transfer.
5. Embryo Transfer
The ability to transfer well is one of the most critical factors contributing to the cycle outcome. At IVFMD, most embryo transfers are conducted on day 5 of culture. The transfer procedure is painless and does not require sedation or anesthesia.
One or two embryos with the best grading scores are loaded into a soft catheter and delivered into the uterus at a depth previously determined during the trial transfer visit. In difficult cases, ultrasound guidance is used to assist the transfer. The remaining embryos are frozen for future use if they meet freezing criteria.
Below is a nice video summary of the IVF process.