Frozen Embryo Transfer: Hormone Replacement
Frozen Embryo Transfer Using Hormone Replacement: A Step-by-Step Guide
For patients with irregular cycles or ovulation disorders, and for patients who need to plan their therapy around time constraints, we can create an artificial menstrual cycle for FET. This involves treatment with an oral estrogen medication and progesterone (usually administered vaginally). This treatment is well established. Pregnancy rates are equivalent when compared to natural cycle FET. We sometimes recommend a trial (practice) cycle before the actual FET cycle so we can perform an endometrial biopsy to ensure that the medication dosages produce the proper development of the uterine lining. In addition, if you have been pregnant, we recommend a repeat uterine measurement before FET. If you have never had an endometrial biopsy to evaluate the development of the lining of the uterine cavity or if it has been longer than a year or if you have risk factors for uterine structural abnormalities, we will recommend a uterine cavity evaluation prior to FET, either with a saline infusion sonohystogram, office hysteroscopy or a hysterosalpingogram. The steps involved in FET with hormone replacement include:
- Hormone therapy (Estrace® and progesterone)
- Embryo transfer
- Hormonal studies and pregnancy test
- Follow-up consultation
Step 1 - Estrogen Therapy
It is important that you start estrogen therapy on the first day of your period. A dose of estrogen is usually administered for 14 days, although shorter or longer cycles may be used, Estrace® is the most common form of estrogen we use. This is a pill containing 2 mg of estradiol, the same hormone produced by the ovaries. We will have you take one pill twice a day for about 14 days. After about 14 days of Estrace®, (your physician may vary the dose or duration of therapy) progesterone is added. This may be administered vaginally or as an intramuscular injection. Estrace® and progesterone are continued until the day of the pregnancy test (usually 12 days after embryo transfer). If the test is positive, these medications may be continued for several weeks. Depending upon the individual physician’s protocol you may also be treated with oral medications such as methylprednisolone and doxycycline prior to the transfer.
Step 2 - Embryo Transfer
Embryo transfer is usually performed on the third to fifth day of progesterone therapy. As with natural cycle FET, embryos are thawed on the morning of the scheduled frozen embryo transfer. In our laboratory, approximately 60-70 percent of embryos survive cryopreservation and thawing. We usually transfer 1 to 2 embryos during each FET cycle. However, this number is flexible, and your physician will discuss this issue with you. Excellent FET pregnancy rates occur in most cases with the transfer of one to two embryos, which also minimizes the risk of multiples. The transfer of more embryos may increase the likelihood of a multiple pregnancy, which increases the pregnancy risks for the woman and the fetuses. The actual embryo transfer itself is identical to the embryo transfer following in vitro fertilization-embryo transfer. Depending upon the physician’s protocol the embryo transfer may be accomplished under ultrasound guidance which will require the bladder to be full. A small plastic catheter is passed gently through the cervix into the uterus. After waiting for 1-2 minutes to allow any mild cramping to resolve, the embryos are deposited into the cavity along with a small amount of fluid. You will be discharged after resting for 20 minutes. No anesthesia is required for the embryo transfer.
Step 3 - Hormonal Studies - Pregnancy Test
We will usually perform a serum pregnancy test 12-14 days after the embryo transfer. If the test is positive, we may also measure serum progesterone. On occasion, we may repeat tests every two or three days. If the test is negative, hormone therapy is discontinued and a period usually begins in a few days. Near the end of that period, your physician may request a vaginal sonogram and/or serum progesterone level.
Step 4 - Follow-up Consultation
If the pregnancy test is positive, we will perform a vaginal sonogram about three weeks later. At this point, we are usually able to identify the number of embryos and can often see a heartbeat. The risk of pregnancy loss is low after this developmental milestone. If the procedure is unsuccessful, you should schedule a consultation with your physician. We will review the procedure and discuss further treatment options.