Back to back FETs

Question

Answer

The answer to both questions is yes! However, I am not a proponent of natural cycle FET. See below:

Until less than a decade ago, most women undergoing IVF would have embryos transferred to the uterus in the same cycle that the egg retrieval was performed (“Fresh” Embryo Transfer). This was because embryo cryopreservation (freezing) was a hazardous undertaking.  In fact, it resulted in about 30% not surviving the freezing process and those that did, having about one half the potential of “fresh embryos to implant and propagate a viable pregnancy. The main reason for the high attrition rate associated with embryo cryopreservation is that the “conventional” freezing” process that was done slowly and this resulted in ice forming within the embryo’s cells, damaging or destroying them. The introduction of an ultra-rapid cryopreservation process (vitrification) freezes the embryos so rapidly as to avoid ice crystals from developing. As a result, >90% survive the freeze/thaw process in as good a condition as they were prior to being frozen and thus without being compromised in their ability to propagate a viable pregnancy.

Recently, there have been several articles that have appeared in the literature suggest that an altered hormonal environment may be the reason for this effect.  There have also been reports showing that when singletons (pregnancy with one baby) conceived naturally are compared to singletons conceived through a “fresh” embryo transfers they tend to have a greater chance of low birth weight/prematurity. This difference was not observed in babies born following FET.  Hence, there is a suspicion that the altered hormonal environment during the fresh cycle may be the causative factor.

Available evidence suggests that FET (of pre-vitrified blastocysts) is at least as successful as is the transfer of “fresh” embryos and might even have the edge. The reason for this is certainly unlikely to have anything to do with the freezing process itself. It more than likely  has to do with two factors:

1. An ever increasing percentage of FET’s involve the transfer of PGS-tested, fully karyotyped, euploid blastocysts that have a greater potential to propagate viable pregnancies, than is the case with “fresh” ET’s where the embryos have rarely undergone prior PGS selection for “competency”…and,
2. With targeted hormone replacement therapy for FET, one is far better able to better to optimally prepare the endometrium for healthy implantation than is the case where embryos are transferre3d following ovarian stimulation with fertility drugs.

There are additional factors other than method used for embryo cryopreservation that influence outcome following FET. These include

• An emerging trend towards selective transferring only advanced (day 5-6) embryos (blastocysts).
•  (PGS) to allow for the selective transfer of genetic competent (euploid) embryos
• Addressing underlying causes of implantation dysfunction (anatomical and immunologic uterine factors) and
•  Exclusive use of ultrasound guidance for delivery of embryos transferred to the uterus.

Against this background, the use of FET has several decided advantages:

• The ability to cryostore surplus embryos left over after fresh embryo transfer
• The ability to safely hold embryos over for subsequent transfer in a later frozen embryo transfer (FET) cycle (i.e. Staggered IVF) in cases where:

• 1. Additional time is needed to perform preimplantation Genetic testing for embryo competency.
  2. In cases where ovarian hyperstimulation increases the risk of life-endangering complications associated with critically severe ovarian hyperstimulation syndrome (OHSS).
  3. To bank (stockpile) embryos for selective transfer of karyotypically normal embryos in older women or those who are diminished ovarian reserve
  4. The ability to store embryos in cases of IVF with third party parenting (Egg Donation; Gestational Surrogacy and Embryo donation) and so improve convenience for those couples seeking such services.

Preimplantation Genetic Sampling with FET:

The introduction of preimplantation genetic sampling (PGS) to karyotyping of embryos for selective transfer of the most “competent” embryos, requires in most cases that the tested blastocysts be vitribanked while awaiting test results and then transferred to the uterus at a later date. Many IVF programs have advocated the routine use of PGS in IVF purported to improve IVF outcome. But PGS should in my opinion should only be used selectively. I do not believe that it is needed for all women undergoing IVF. First there is the significant additional cost involved and second it will not benefit everyone undergoing IVF, in my opinion.

While PGS is a good approach for older women and those with diminished ovarian reserve (DOR) and also for woman who experience recurrent pregnancy loss (RPL) or “unexplained” recurrent IVF failure recent data suggests that it will not improve IVF success rates in  women under 36Y  who have normal ovarian reserve, who represent the majority of women seeking IVF treatment. Nor is it needed in women (regardless of their age) undergoing IVF with eggs donated by a younger donor.  This is because in such women about 1:2/3 of their eggs/embryos are usually chromosomally normal, and in most cases will upon fertilization produce multiple blastocysts per IVF attempt, anyway. Thus in such cases the transfer of 2 blastocysts will likely yield the same outcome regardless of whether the embryos had been subjected to PGS or not. The routine use of

It is another matter when it comes to women who have diminished ovarian reserve and/or DOR contemplating embryo banking and for women with unexplained recurrent IVF failure, recurrent pregnancy loss and women with alloimmune implantation dysfunction who regardless of their age or ovarian reserve require PGS for diagnostic reasons.

Embryo Banking: Some IVF centers are doing embryo banking cycles with Preimplantation Genetic Screening (PGS).  With Embryo Banking” several IVF cycles are performed sequentially (usually about 2 months apart), up to the egg retrieval stage. The eggs are fertilized and the resulting advanced embryos are biopsied. The biopsy specimens are held over until enough 4-8 blastocysts have been vitribanked, thus providing a reasonable likelihood that one or more will turn out to be PGS-normal. At this point the biopsy specimens (derived all banking cycles) are sent for PGS testing at one time (a significant cost-saver), the chromosomally normal blastocysts are identified and the women are scheduled for timed FET procedures….. with a good prospect of  a markedly improved chance of success as well as a reduced risk of miscarriage.

Standard (proposed) Regimen for preparing the uterus for frozen embryo transfer FET) is as follows:

 The recipient’s cycle is initiated with an oral contraceptive-OC (e.g. Marvelon/Lo-Estrin; Lo-Ovral etc) for at least 10 days. This is later overlapped with 0.5 mg. (10 units) Lupron/Lucrin (or Superfact/Buserelin) daily for 3 days. Thereupon the OC is withdrawn and daily 0.25 mg (5 units) of Lupron/Lucrin/Superfact injections are continued. Menstruation will usually ensue within 1 week. At this point, an ultrasound examination is performed to exclude ovarian cyst(s) and a blood estradiol measurement is taken (it needs to be <70pg/ml) until daily progesterone administration is initiated some time later. The daily Lupron/Lucrin/Superfact is continued until the initiation of progesterone therapy (see below).

Four milligram (4mg) Estradiol valerate (Delestrogen) IM is injected SC, twice weekly (on Tuesday and Friday), commencing within a few days of Lupron/Lucrin/Superfact-induced menstruation. Blood is drawn on Monday and Thursday for measurement of blood [E2].  This allows for planned adjustment of the E2V dosage scheduled for the next day. The objective is to achieve a plasma E2 concentration of 500-1,000pg/ml and an endometrial lining of >8mm, as assessed by ultrasound examination done after 10 days of estrogen exposure i.e. a day after the 3^rd dosage of Delestrogen..  The twice weekly, final (adjusted) dosage of E2V is continued until pregnancy is discounted by blood testing or an ultrasound examination. Dexamethasone 0.75 mg is taken orally, daily with the start of the Lupron/Lucrin/Superfact. Oral folic acid (1 mg) is taken daily commencing with the first E2V injection and is continued throughout gestation. Patients also receive Ciprofloxin 500mg BID orally starting with the initiation of Progesterone therapy and continuing for 10 days.

Luteal support commences 6 days prior to the ET, with intramuscular progesterone in oil (PIO) at an initial dose of 50 mg (P4-Day 1).  Starting on progesterone administration-Day 2, PIO is increased to 100 mg daily continuing until the 10^th week of pregnancy, or until a blood pregnancy test/negative ultrasound (after the 6-7^th gestational week), discounts a viable pregnancy.

Also, commencing on the day following the ET, the patient inserts one (1) vaginal progesterone suppository (100 mg) in the morning + 2mg E2V vaginal suppository (in the evening) and this is continued until the 10^th week of pregnancy or until pregnancy is discounted by blood testing or by an ultrasound examination after the 6-7^th gestational week. Dexamethasone o.75mg is continued to the 10^th week of pregnancy (tailed off from the 8^th to 10^th week) or as soon as pregnancy is ruled out. With the obvious exception of the fact that embryo recipients do not receive an hCG injections, luteal phase and early pregnancy hormonal support and immuno-suppression is otherwise the same as for conventional IVF patients.  Blood pregnancy tests are performed 13 days and 15 days after the first P4 injection was given.

Note: One (1) vaginal application of Crinone 8% is administered on the 1^st day (referred to as luteal phase day 0 – LPO). On LP Day 1, they will commence the administration of Crinone 8% twice daily (AM and PM) until the day of embryo transfer.  Withhold Crinone on the morning of the embryo transfer and resume Crinone administration in the PM.   Crinone twice daily is resumed from the day after embryo transfer. Contingent upon positive blood pregnancy tests, and subsequently upon the ultrasound confirmation of a viable pregnancy, administration of Crinone twice daily are continued until the 10^th week of pregnancy.

Regime for Thawing and Transferring Cryopreserved Embryos/Morulae/Blastocysts:

Patients undergoing ET with cryopreserved embryos/morulas/blastocysts will have their embryos thawed and transferred by the following regimen.

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INTRODUCING SHER FERTILITY SOLUTIONS (SFS)

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Geoff Sher