Aproach Too Ivf at Sirm
STEPWISE APROACH TO IVF AT SIRM:
Geoffrey Sher MD
1. CONTROLLED OVARIAN HYPERSTIMULATION (COH)
IVF success rates are dependent upon the number of the mature eggs and healthy embryos available for transfer. A woman undergoing IVF is given fertility drugs for two reasons: (1) to enhance the growth and development of her ovarian follicles in order to produce as many healthy eggs as possible and (2) to control the timing of ovulation so that the eggs can be surgically retrieved before they are ovulated, with as many of them being mature as possible. In cases where the woman has previously received fertility drugs, the subsequent treatment regime is largely based upon her most recent response to such treatment. For a woman receiving gonadotropins for the first time, the dosage and regimen is determined by her blood FSH, E2, and Inhibin-B concentrations on the 3rd day of a preceding menstrual cycle (see above), medical history and body habitués.
In most cases, the woman begins her cycle of treatment by taking oral contraceptive birth control pills (OCP/BCP) for 6-30 days before initiating daily injections of leuprolide acetate (Lupron). Both the OCP/BCP and Lupron are administered together for an additional 4 to 6 days where upon the BCP is withdrawn while daily Lupron injections are continued. Menstruation will usually follow about 3 to7 days after stopping the BCP. In this way it is possible to accurately plan the onset of menstruation by varying the length of time on the BCP. In this way we are able to schedule each cycle of IVF to the convenience of the patient and the medical team. Additionally, the combined use of BCP and Lupron reduces the risk of Lupron-induced ovarian cyst formation, thereby largely avoiding the need to delay or cancel the cycle of treatment.
As soon as menstruation begins, blood is taken and if the plasma E2 concentration is less than 70 pg/ml, the patient is ready to initiate ovarian stimulation with gonadotropins. If the E2 level is greater than 70 pg/ml, Lupron therapy is continued at the same (or at an increased) dosage for a few more days, whereupon the E2 concentration is re-measured. Subsequent failure of the E2 to fall below 70 pg/ml is an indication for a pelvic ultrasound for the detection of an ovarian cyst, the presence of which usually mandates the performance of an ovarian cyst needle aspiration.
Lupron injections are either continued at a reduced daily dosage or (as is now becoming common practice at SIRM, we stop Lupron and switch to low dose GnRH antagonist (Antagon or Cetrotide). On a designated day (usually within a week and a half of the onset of menstruation), a specified regime of gonadotropins (e.g., Gonal F, Follistim, Bravelle, and Repronex) therapy is initiated. Those patients receiving mini-dose heparin/ therapy begin this treatment on the first day of receiving gonadotropins. Some patients receive Estradiol Valerate (E2V) injections and/or vaginal estradiol suppositories for a week or longer, prior to and during gonadotropin therapy. Patients with a history of a poor endometrial lining may require Viagra vaginal suppositories to improve the uterine lining. Patients requiring intravenous immunoglobulin (IVIg) therapy receive this medication by intravenous infusion 7-10 days prior to embryo transfer.. All IVF patients receive oral dexamethasone 0.75 mg. (1 tablet) daily, commencing with the start of Lupron and continuing until the first blood beta-HCG test (i.e., the chemical diagnosis of pregnancy). Women, who have a positive blood pregnancy test 9-11 days after embryo transfer, continue taking dexamethasone and heparin beyond the ultrasound confirmation of pregnancy, which is performed at the 6-7 gestational week. In cases where the blood pregnancy test fails to reveal an appropriate increase in the quantitative beta HCG concentration, heparin therapy is discontinued, and the dexamethasone dosage is slowly reduced over a few weeks and then stopped. Pregnant women continue dexamethasone as well as heparin treatment until the 8th-10th week of pregnancy, whereupon the former is tapered off over 1-2 weeks and then stopped and the latter is abruptly discontinued. All patients receive an oral antibiotic beginning about seven days after the initiation of gonadotropin therapy and continuing for a few days after the embryo transfer procedure. Two days after the initiation of gonadotropin injections, the dosage of gonadotropins is substantially reduced, and is then maintained at this lower level until the administration of HCG. Dosage adjustments are sometimes made during the course of the cycle, based upon the patient’s response to medication.
Commencing seven days after the initiation of gonadotropin therapy, the patient undergoes serial ultrasound and plasma estradiol evaluations to monitor her ovarian response. These assessments are aimed at determining the ideal day for administering 10,000 IU HCG to trigger the final maturation of the egg(s) and the production of progesterone by the ovaries. Lupron or Antagon/Cetrotide and gonadotropin injections are discontinued on this day and the patient is scheduled for egg retrieval approximately 35 hours after receiving the intramuscular injection of HCG. Subcutaneous heparin injections are discontinued approximately 12 hours prior to the egg retrieval and re-started after the embryo transfer procedure.
2. THE EGG RETRIEVAL
Egg retrieval involves a non-surgical procedure where under direct ultrasound guidance, a needle is passed along the side of a vaginal ultrasound probe through the top of the vagina into follicles (small fluid filled spaces that each contain an egg), within the ovary (ies). The follicular fluid is aspirated and collected in a test tube, which is promptly delivered to the embryologist for analysis and processing. The procedure itself is relatively painless, however patients commonly experience some residual postoperative abdominal discomfort and /or cramping that rarely persists for more than a few hours. Postoperatively all patients are given detailed instructions and are discharged within an hour or two with a prescription for analgesics (pain killers) and other medications as indicated.
3. SPERM PROCESSING
Sperm is usually obtained from a masturbation specimen derived from the male partner. On some occasions however, physical, medical and/or religious constraints demand that sperm be obtained through condom collection following intercourse, or by inserting a needle directly into the testicle(s) under local anesthesia and aspirating sperm Testicular Sperm Extraction (TESE) or Percutaneus Epididymal Sperm Aspiration (PESA). TESE or PESA are procedures of choice in cases where there is blockage of the sperm ducts (as occurs following vasectomy or following severe injury or infection), or where the man is born without sperm ducts (congenital absence of the vas deferens). Sometimes, in cases of retrograde ejaculation, sperm can be collected from the man's bladder. Infrequently, in men with spinal cord injuries, ejaculation is facilitated by electrical stimulation (electro-ejaculation). Donor sperm, obtained from a sperm bank, can be used when indicated.
Sperm must undergo a biochemical and structural changes known as capacitation, before an egg can be fertilized. Capacitation (which under normal circumstances takes place in the woman's reproductive tract) must be accomplished in the embryology laboratory prior to insemination of the eggs. Motile sperm are processed and activated in specialized culture media and sophisticated techniques are used to enhance poorly mobile sperm.
4. FERTILIZATION
In vitro fertilization literally means "fertilization in glass". Fluid aspirated from ovarian follicles is examined in the embryology laboratory. The eggs are identified and extracted and are placed in a specialized culture medium. Several hours later, approximately 50,000-100,000 processed sperm are placed around each of the eggs. The eggs and sperm are allowed to incubate together in a carefully controlled environment. Approximately 16-24 hours later, the eggs are inspected microscopically for fertilization as evidenced by the presence of two nuclear bodies. These binuclear unicellular bodies are referred to as "pro-nuclear embryos".
ICSI (Intracytoplasmic sperm injection) has literally revolutionized the treatment of male infertility. The procedure involves the direct injection of a single sperm into each egg under direct microscopic vision. The successful performance of ICSI requires a high level of technical expertise. In centers of excellence, when ICSI is employed, the IVF birth rate is unaffected by the presence and severity of male infertility. In fact, even when the absence of sperm in the ejaculate requires that ICSI be performed on sperm obtained through Testicular Sperm Extraction (TESE) or PESA, the birth rate is no different than when IVF is performed for indications other than male infertility.
The introduction of ICSI has made it possible to fertilize eggs with sperm derived from men with the severest degrees of male infertility and in the process to achieve pregnancy rates as high, if not higher than that which can be achieved through conventional IVF performed in cases of non--male factor related infertility. The indications for ICSI have broadened dramatically, with the process now being used for a variety of indications other than male factor infertility. For example, at SIRM we now use ICSI to assist in the fertilization of eggs that are believed to have a hardened or thickened outer envelopment (zona pellucida). This is frequently found in the association with polycystic ovarian disease (PCO) and in eggs derived from older women (over 40 years). ICSI is also frequently recommended in cases of "unexplained infertility" and where there is a history of poor fertilization during one or more prior IVF attempts.
Assisted Hatching: In selected cases where it is felt that the zona pellucida (the envelopment of the embryo/blastocyst) is unusually tough or thickened, a process known as Assisted Hatching (AH) may be employed. The process involves deliberately weakening of the wall of the embryo mechanically (using laser) or chemically (using acid tyrodes solution), so as to promote hatching (rupturing) and thereby facilitate implantation. It remains controversial as to whether AH actually improves pregnancy rates.
Embryos/blastocysts are transferred to the uterus via a thin Teflon catheter. This procedure is often conducted under ultrasound guidance with the woman on her back (in the lithotomy position) and with a full bladder. The procedure is usually painless and takes less than thirty minutes to complete. Sometimes a prior trial embryo transfer (performed on the 8th day of gonadotropin stimulation) points towards potential difficulty in transferring the embryo(s)/blastocyst(s) to the uterus. In such cases, the procedure may be performed with patient under anesthesia. In rare cases where tortuosity or partial obstruction of the canal leading in to the uterus (i.e. the cervical canal) severely complicates conventional embryo transfer, a method known as Transmyometrial Embryo Transfer (TMET) can be used. With TMET, the patient is anesthetized and a needle is passed along the side of a transvaginal ultrasound probe, through the wall of the uterus into the cavity. A catheter is passed through the needle with its tip protruding into the uterine cavity. The needle is partially withdrawn and the blastocyst(s)/ embryo(s) are injected. After the embryo transfer the woman remains immobile for approximately one hour and is thereupon discharged with specific instructions.
5. SELECTING THE MOST “COMPETENT” EMBRYOS FOR TRANSFER
A. MICROSCOPIC EMBRYO GRADING USING THE GRADUATED EMBRYO SCORING (GES) SYSTEM: Few would argue that the uterus likely provides a better environment for embryos to flourish than the incubator in an IVF laboratory. The presumption has always been that it would probably be best to transfer healthy embryos to the uterus sooner rather than later. It is against this background that we recently serially evaluated 1068 embryos derived from 139 women under 40 years of age, microscopically over a period of 72 hours following IVF, searching for criteria that would help predict embryo quality and implantation potential as early as possible. The results of this study led to the introduction of Graduated Embryo Scoring (GES). The GES scores each individual embryo out of a maximum of 100 points. Those embryos that are not transferred to the uterus are subsequently re-examined 2-3 days later to determine whether they have developed into blastocysts. The implantation rate per embryo is defined by the number of gestational sacs detected by ultrasound examination 4 weeks following embryo transfer (ET). The results revealed the following:
- Embryos with a GES score of 90-100 had a 64% chance of developing into good quality blastocysts. Embryos with a GES score of 70-85 had a 31% chance of developing into good quality blastocysts while those scoring 30-65 had only an 11% chance of doing so.
- Embryos with a GES score of 70-100 had a 44% chance of developing into good quality blastocysts and a 39% implantation rate. Embryos scoring 0-65 had only a 9% chance of developing into good quality blastocysts and a 24% implantation rate.
- Among individual patients, if at least one transferred embryo scored 70 or better, the pregnancy rate was 59%. If the highest scoring transferred embryo scored <70, the pregnancy rate was only 34%.
Blastocysts are graded on the basis of their cellularity, differentiation of the trophectoderm, the inner cell mass and the blastocele. As an example, a grade 1 blastocyst when compared with grades 2 or 3, contains more cells, have a more expanded blastocele, a more prominent inner cell mass and a hypercellular, well differentiated trophectoderm. Grades 1 and 2 blastocysts have about a 40 % implantation rate, as compared to about 10% for grade 3.
Through GES it is possible to establish a sounder basis for advising patients with regard to having their embryos transferred early (on the 3rd day following fertilization) or waiting 2-3 days longer in order to have blastocysts transferred. GES also establishes a rational basis for deciding on the number of embryos/blastocysts to be transferred, in order to minimize the occurrence of high-order multiple pregnancies. In the past, we have favored transferring GES-high scoring embryos (70-100) sooner (i.e., on day 3) rather than later, on day 5 or 6 (as blastocysts). Embryos with a lower score were allowed to continue to the blastocyst stage prior to being transferred, in order to provide more confidence regarding their implantation potential. The recent introduction of the Embryo Marker Expression Test (EMET) has changed all this…. (SEE BELOW).
B. EMBRYO VERSUS BLASTOCYST TRANSFER: It has long been recognized that the more advanced the embryo’s state and rate of development, the more likely it is to implant successfully into the uterine lining. It is also well established that “poor quality embryos” tend to divide (cleave) and develop more slowly, and are much more likely to arrest before reaching the blastocyst stage. It is therefore not surprising that researchers would focus on trying to grow embryos to the blastocyst stage in order identify “good quality embryos” that are more likely to implant successfully, by their ability to survive to the blastocyst stage of development.
Over the past five years, researchers in Australia, Scandinavia and in the U.S simultaneously developed a new generation of culture media that reliably support the growth of embryos to the fifth or sixth day. This development was based on the premise that the metabolic needs of the early embryo change as it moves from the fallopian tube to the endometrial cavity and the new media are designed to mimic these environmental changes. Using “sequential culture systems,” approximately 40% of “good quality” (7 cells or more) day 3 embryos can be grown to the blastocyst stage and have made blastocyst culture feasible for many IVF programs.
The current inability to predict with certainty which embryos will successfully implant into the uterine lining still prompts many IVF practitioners, motivated with the desire to optimize IVF success rates, to transfer large numbers of embryos at a time. While such practice indeed increases IVF pregnancy rates, it unfortunately also results in an unacceptably high incidence of multiple pregnancies, with devastating consequences to the resulting, often severely premature, newborn babies.
It is important to note that in spite of the introduction of specialized culture media and new techniques for culturing blastocysts, it is still only possible to enable about 40% of “good quality” embryos to progress to blastocysts. However, since blastocysts are more likely to implant than are day 3 “good quality embryos”, it is possible through the selective transfer of fewer blastocysts to improve IVF success rates while at the same time, significantly curtailing the incidence of high-order multiple pregnancies (triplets or greater).
However, few would argue that the uterus likely provides a better environment for embryos to flourish than the incubator in an IVF laboratory. The presumption has always been that it would probably be best to transfer healthy embryos to the uterus sooner rather than later. Moreover, even the best microscopic embryo grading systems are inherently flawed because they do not have a high level of negative or positive predictive value. Although an improvement of most other embryo grading systems, the Graduated Embryo Scoring (GES) system developed at SIRM is also somewhat limited in this regard.