Tubal Embryo Transfer (TET)TET is a technique that combines IVF (In Vitro Fertilization) with a tubal transfer. TET stands for'Tubal Embryo Transfer". Embryos are placed via catheter directly into the women's fallopian tubes. This usually involves a minor surgical procedure that allows the patient to go home the same day with a minor degree of pain. That allows embryos to make their way to the uterus for implantation according to a normal timetable.
In contrast, IVF places embryos directly into the uterus. The success rate with TET is higher than standard IVF, but can only be performed if the woman has normal fallopian tubes.TET allows couple with serious male -factor infertility (eg., low sperm count, motility or poor quality) the advantage of a tubal transfer when it is combined with the ICSI fertilization- procedure. Its advantage over ZIFT is that it allows for the assessment of fertilization and embryo quality.
In a fertile couple, pregnancy begins with the release of an ovum (egg) from the woman's ovaries, The egg enters the fallopian tube where it meets with the sperm that have traveled there, following intercourse, from the vagina. The sperm normally fertilize the egg in the fallopian tube. The fertilized egg, now called an embryo, begins to divide and in four days contains many cells. At this time, the embryo moves fuom the fallopian tube to the uterine cavity where it "floats" for another two to three days. The embryo then implants in the uterine wall with a resultant pregnancy. TETs major advantages over IVF is that the technique allows the body to nurture the embryos in the more natural environment of the fallopian tubes, while also ensuring that they wiil enter the uterine cavity at the optimal time for implantation. TETs advantage over GIFT is the opportunity to observe that fertilization took place.
To prepare her body for the TET procedure the woman rcceives hormone injections to stimutate development of the ovarian fotlicles, the sac-like structures that contain the eggs. Administering hormones increases the chances of retrieving many ripened eggs, each one capable of being fertilized and producing a pregnancy. HMG (human menoparsd gonadotropin) and recombinant FSH (follicle- stimulating hormone) are the hormones used to stimulate the production of follicles.Up to three or more embryos are returned to the patient depending on her age and the quality of her embryos. If the patient has extra embryos they can be frozen for future attempts at pregnancy via a FET procedure.
To begin a cycle of TET the patient's cycle will begin to be monitored in the previous month. At a certain point the patient will begin administering a GnRH-Agonist or a GnRH-Antagonist to prevent the premature surge of LH (luteinizing hormone) from triggering ovulation before the eggs can be retrieved. After the menstrual cycle begins the patient will be examined by transvaginal ultrasound to check the status of their ovaries and pelvis in preparation for hormone injections. The patient will also have baseline bloodwork performed at this time. Once the patient has begun administering the hormone injections (HMG or FSH) approximately four days later they will begin periodic monitoring by ultrasound examination and blood estrogen level.
Later that day the patient will be informed how much HMG or FSH they will be receiving until their next monitoring appointment. The dosage and timing will depend on patient's age, previous response, and the estrogen level and ultrasound results demonstrated that day. When the monitoring shows the eggs are ripe and ovulation is imminent, an injection of HCG (human chorionic gonadotropin) is administered to the patient to complete the egg maturation process and prepare the eggs for retrieval.
The patient is admitted for the outpatient TET egg retrieval procedure the next day.A semen sample from the husband is obtained while the wife is undergoing the egg retrieval procedure. It is then washed and prepared with the most active and healthy sperm being selected for fertilization of the wife's eggs. Eggs are retrieved by transvaginal needle aspiration (no surghal incision) via an ultrasound guide while the patient is under light sedation. The aspirated follicular fluid (containing the eggs) is placed in a laboratory dish and the eggs are observed under a microscope for maturity and quality. The eggs are then transferred to a culture dish where they are incubated in a special culture medium. Later, sperm are added to the culture dish so fertilization can take place. Alternatively, the eggs may be fertilized by the ICSI procedure. The patient will be able to go home a few hours later with minimal discomfort.
Two days after the egg retrieval procedure the patient retums for the oupatient surgical tubal transfer, The embryos are loaded into a catheter, which is then placed into the patient's fallopian fubes through a very small incision in her abdomen while she is under general anesthesia. They are then released into the fallopian tubes where the embryos are nurtured before moving down into the uterus for implantation approximately five days later. TET is intended to be an outpatient procedure and the patient almost always goes home the same day. After she is discharged she will be asked to limit her activity for the next week and get plenty of rest.Progesterone support by IM injection and/or vaginal suppository or cream will begin after the egg retrieval procedure. The hormone progesterone suppotts a pregnancy by preparing the endometrial lining so it is receptive to implantation. In one week the patient will have a blood test to check their hormone levels and further instructions for hormone supplementation will be given later that day. Two weeks after the egg retrieval the patient will have a blood pregnancy test, a quantitative beta HCG. If the test is positive the patient will continue hormone suplementation for four to eight weeks.
If the patient does not get pregnant they will discontinue these hormones. They should consider undergoing another cycle in the future as subsequent cycles would also have a high pregnanry rate. Another option is to go through a FET if the patient's cycle yielded extra embryos for freezing.
Contact our clinic for more information or to arrange a consultation appointment to see if TET or one of our many other procedures will help you fulfill your dream of parenthood.