What is In Vitro Fertilization?
In Vitro Fertilization (IVF) is a process in which oocytes (eggs) are fertilized with sperm outside of the womb in a laboratory. The resulting embryos are transferred to the patient’s uterus with the intent to establish a pregnancy. The term In Vitro, from the Latin means in glass (such as the glass containers, test tubes and petri dishes used in the laboratory). Initially, IVF was developed to overcome infertility due to fallopian tube problems in women (fallopian tubes are the conduits for the fertilized egg to travel to the uterus), but it has become an appropriate treatment for virtually all forms of infertility in both men and women. For example, the development of Pre-implantation Genetic Testing (PGS/PGD) on embryos is now leading the field of IVF. Pre-implantation Genetic testing is being used more and more to select the most viable embryos helping to facilitate the healthiest baby possible.
- Ovarian Stimulation: Treatment cycles typically consist of a regimen of fertility medications to stimulate the ovaries to produce multiple follicles with oocytes. In most cases injectable gonadatropins (usually FSH analogues) are given to the patients who are closely monitored with blood tests and ovarian ultrasounds to assess the response of the ovaries.
- Egg Retrieval: Once the follicles have reached the appropriate maturity, human chorionic gonadotropin (B-hCG) is given to the patient. This substance acts as an analogue of lutenizing hormone and would cause ovulation about 36 hours after the injection but the egg retrieval procedure takes place just prior to that time in order to recover the eggs from the follicles. The eggs are collected using a needle introduced into the pelvis through the vaginal wall guided by ultrasound. Through this needle, the follicles are aspirated and the follicular fluid is handed to our IVF laboratory (which is adjacent to our operating room) in order for the embryologist to identify the eggs. The egg retrieval procedure usually takes about 15-20 minutes and is done under anesthesia (usually propofol). The patient is then returned to the recovery room which is adjacent to our operating room to recover.
- IVF Laboratory and Fertilization: During the egg retrieval, the male is producing his sperm sample or if the semen is provided by a sperm donor it will be thawed and prepared for fertilization. The semen is prepared for fertilization by removing the inactive cells and seminal fluid. The oocytes, once in the laboratory are stripped of the surrounding cells and are thus prepared for fertilization. We prefer to perform intracytoplasmic sperm injection (ICSI), in which a single sperm is identified and injected into the cytoplasm of the egg so we can ensure the highest amount of fertilization possible and thereby obtain as many embryos as possible for the patient(s) regardless of whether there is a male factor or not. Within 24 hours, evidence of fertilization can be visualized through the microscope. The fertilized egg is placed in culture media and is left to grow for about 48 hours. Embryos can be transferred either three days after retrieval or later at the blastocyst stage which is known as a day five embryo. We have shown that if good quality blastocysts are available for transfer, the pregnancy rate is higher than a day 3 transfer.
- Embryo Transfer: Embryos are graded by the embryologist according to the number of cells, growth and degree of fragmentation. Also in some cases where we have performed Preimplantation Genetic Diagnosis (PGD), we will only transfer embryos that have tested normal. The number of embryos to be transferred depends on the number of embryos, the quality of the embryos and in the case of PGS, the number of normal embryos available and the age of the woman producing the embryos. The rationale behind the number of embryos to be transferred is to optimize the chance of pregnancy and minimize the chance of carrying a multiple pregnancy. The embryos that are graded as being the “best” are loaded into a thin, plastic catheter which is passed gently through the woman’s vagina and cervix into the uterine cavity under ultrasound guidance. The embryos are deposited in the uterine cavity. After the embryo transfer procedure, the patient stays in a resting position for about an hour and then leaves the clinic and goes on bed rest for three days.
- Post-Embryo Transfer Monitoring: During the weeks following the embryo transfer, the patient receives progesterone supplementation and is monitored with a series of blood tests. Approximately 12 days after the embryo transfer the first pregnancy blood test will be performed. If the test is positive, a series of blood tests will be performed to follow the beta HCG levels and about six weeks after the transfer the first pregnancy ultrasound will be performed.
- Success Rates: Please see our section on statistics and success rates for a full explanation of IVF success rates and statistics. Over the past several years, La Jolla IVF success rates have generally improved, so that approximately one in every three (non PGS) IVF cycles will result in the birth of a baby. For patients that selected to do PGS with transferring two normal embryos, the pregnancy rate is at least 75%. Success rates at La Jolla IVF over the past two years in our intimate couple patient population where the egg giver is also the woman into which the embryos are being transferred and where the sperm giver is the partner or husband, our success rates are as follows:
Egg giver under 35 years old...............Clinical pregnancy rate 46.8%
Egg giver 35 – 40 years old.................Clinical pregnancy rate 36.6%
Egg giver 40 years and older...............Clinical pregnancy rate 25%
A clinical pregnancy is one that is documented on ultrasound to have fetal cardiac activity.
As can be seen from these success rates, the age of the egg giver is one of the most important factors to be considered when looking at statistics. Another compounding factor is whether a patient has an inherently poor prognosis to start off with such as failing IVF cycles previously or being very difficult to stimulate and being a poor responder to the IVF medications. Each couple should be looked at individually and to compare success rates may not always be meaningful.