In Vitro Fertilization (IVF) is one of the Assisted Reproductive Technologies (ARTs) used for couples with infertility that cannot be treated using simpler methods. The four main steps in IVF are:
It is a standard procedure in ART. The aim is to stimulate the growth of several follicles by injections of FSH-containing compounds. There are different protocols used according to the age of the patient and the status of her ovarian reserve. Initially drugs are given to achieve down regulation or to bring her own natural hormones to a basal level which will be confirmed by measuring her estradiol levels and a transvaginal ultrasound. Then injectable hormones are given to stimulate her ovaries to induce the growth of multiple follicles. Generally the duration of stimulation in IVF is about 10 days. Continuous monitoring is done using ultrasound and estradiol levels. Following this period once the follicles reach the desired growth stage, an injection of human chorionic gonadotropin (HCG) is then given to invoke follicle and oocyte maturation.
Picture of an ovary with multi follicular development.
It is usually done 34-36 hours following the HCG trigger injection. The hormone matures the eggs, and releases them into the follicular fluid. The procedure is done under short anesthesia. Under ultrasound guidance, the fluid from the follicles is removed using an aspiration needle and a suction apparatus. It takes about 20 minutes to half hour depending on the number of follicles. The aspirated fluid is immediately transferred to the embryology lab taking utmost care that the temperature and Ph is maintained at almost similar conditions as in the body.
During or shortly after the egg collection procedure, the male collects his semen sample. Sometimes giving a sample in an unfamiliar environment under pressure may seem difficult or awkward. In anticipation of such issues we always collect a backup sample of semen which is collected at an earlier date and frozen so that in case of any issues with collection on the retrieval day the frozen sample might be used.
Sperm collected directly from the testicles or donated sperm can also be used in infertility treatments.
The quality of the semen, its motility and the number of sperms, determine whether an IVF or the ICSI method will be used to fertilize the eggs. The most active spermatozoa with normal structure are chosen for fertilization. The fertilization is carried out a few hours after the egg collection.
As soon as the fluid reaches the laboratory, the embryologist will examine the follicular fluid under a microscope. When eggs are found, they are placed in a culture dish. They are grown in a culture medium and kept in an incubator with a controlled environment resembling that of the human body. The eggs are very sensitive to temperature and pH-changes, and therefore are promptly handled on warmed plates at the working place of embryologist.
In case of IVF, the prepared sperm sample is incubated with the eggs in small petri dishes and left to fertilize. Fertilization happens within a couple of hours and the eggs with the attached sperms are transferred into clean droplets of medium in another dish.
The eggs are checked the following day to document fertilization and again the next day to evaluate for early cell division. They are now called embryos and are monitored continuously for further growth.
Following stages of embryos are observed during embryo culture:
Earlier embryos were cultured for two to three days and then transferred to the uterus and/ or were cryopreserved (frozen).
Recent advancements in this area now allow the embryos to grow for five or six days, until they reach the blastocyst stage. Blastocysts have a greater chance of implantation in certain couples. It also allows the transfer of fewer embryos, in some cases only one, and lowers the risk of multiple birth, while increasing the chance of pregnancy.
On day two or three after fertilization, the embryos will be evaluated for blastocyst culture. If there are sufficient numbers of dividing embryos, they will be placed in special blastocyst media and grown for two or three additional days.
Embryos are usually transferred on day 2, 3 or 5 after egg retrieval depending on the number, growth and morphology of embryos. Transfers on day 5 or 6 are called Blastocyst Transfers.
Depending on the quality and number of embryos, they can be transferred to the uterus on the 2nd or 3rd or 5th day after collection of the eggs.
In women less than 35 years of age, not more than two embryos are transferred. In older age group women, about 3 embryos are transferred. The maximum number of embryos transferred will be 2-3.
The procedure of embryo transfer is painless by itself and does not call for any further medical procedures. The embryo is transferred with a tiny plastic catheter through the vagina into the uterus. Pregnancy begins if the embryo implants into the lining of the uterus in a couple of days after transfer into uterus.
After Embryo Transfer, it is advisable to avoid vigorous physical activity while carrying on normal daily life.