The first human birth to result from IVF was achieved in England in 1978.⁴ John and Lesley Brown had 9 years of infertility secondary to bilateral fallopian tube obstruction. Dr. Patrick Steptoe surgically retrieved a single mature oocyte from one of Lesley’s ovaries during a natural cycle. Dr. Robert G. Edwards combined John’s sperm with the oocyte in the laboratory and the resulting embryo was placed into Lesley’s uterus a few days later. On July 25, 1978, Louise Joy Brown was delivered by cesarean section at approximately 37 weeks’ gestation, and weighed 5 pounds 12 ounces.

Although this first human IVF birth employed a surgical procedure to retrieve the oocyte produced in a natural menstrual cycle, most IVF today is performed after ovarian stimulation so that multiple eggs can be retrieved transvaginally with a sonographically guided needle. Currently more than 99% of ART procedures in the United States employ IVF and transcervical embryo transfer.

Gamete Intrafallopian Transfer

GIFT utilizes the same ovarian stimulation and egg retrieval as IVF, but the eggs and sperm are transferred to the fallopian tubes immediately after egg retrieval, forgoing the need for IVF and culture medium. GIFT was developed with the rationale that the fallopian tube was an environment superior to a culture dish for fertilization and early embryo development.

Although early reports of GIFT indicated higher success rates than with IVF, improvements in the formulation of culture media and other laboratory techniques have resulted in equivalent success rates for GIFT and IVF.^5,⁶ A disadvantage of GIFT is that it can only be performed in patients with normal fallopian tubes. Another disadvantage of GIFT compared to IVF is that it generally requires laparoscopy, with all the risks and expenses associated with this outpatient surgery. Currently, GIFT procedures account for less than 0.2% of ART treatments in the United States.

Zygote Intrafallopian Transfer

ZIFT is a hybrid between IVF and GIFT. For ZIFT, oocytes are retrieved using a transvaginal needle, fertilized in vitro, and cultured overnight. Zygote-stage embryos are then laparoscopically transferred to the fallopian tubes approximately 24 hours after oocyte retrieval. ZIFT offers the advantages of IVF with the direct observation of the success of the IVF process. Injection of sperm into the egg can be performed if necessary. It allows the subsequent transfer of the embryos to the fallopian tube for optimal development.

Although some studies comparing ZIFT to conventional IVF have found ZIFT to be superior, other studies have shown little difference.^7,⁸ This uncertainty and the need for two surgical procedures for ZIFT (i.e., transvaginal egg retrieval and laparoscopic embryo transfer) have limited the popularity of this technique. However, ZIFT has found a place in the treatment of infertile women with congenital or acquired cervical abnormalities and in patients who fail to achieve pregnancy after repeated IVF cycles.^9,¹⁰ Currently, ZIFT procedures account for approximately 0.5% of ART treatments in the United States.

INDICATIONS FOR ASSISTED REPRODUCTION

Tubal Factor Infertility

Tubal Adhesions

Tubal adhesions account for 30% to 40% of cases of female infertility. Tubal damage or adnexal adhesion typically arise from salpingitis, appendicitis, endometriosis, or previous pelvic surgery. Laparoscopic surgery to remove adhesions and open tubes can yield pregnancy rates of more than 50% in women with relatively mild disease.¹¹ In women with severe tubal damage or extensive dense adhesions, surgery is unlikely to result in pregnancy. IVF is indicated in these patients and in women who have failed to conceive after infertility surgery.

Hydrosalpinges

Tubal surgery is also indicated in women with hydrosalpinges who are contemplating IVF. Hydrosalpinges are associated with decreased pregnancy and live birth rates after IVF.¹² Although the pathophysiology of this relationship is not completely understood, bilateral salpingectomy improves the success of subsequent IVF, especially in women with bilateral hydrosalpinges.

Tubal Ligation

Up to 25% of women who have undergone bilateral tubal sterilization will come to regret their decision and wish to have more children. Risk factors for tubal ligation regret include young age at time of sterilization, relationship with a new partner, loss of a child, and having been sterilized immediately postpartum or postabortion. Up to 5% will seek tubal anastomosis, which is a highly effective treatment option in properly selected patients.¹³ Success rates depend on the site of the anastomosis, the length of residual tube, the age of the patient, and the presence of other infertility causes.

In vitro fertilization is an effective alternative to surgery for women who have undergone a tubal ligation. This is particularly true for women without adequate residual tubal length, those who are poor surgical candidates, and those who would prefer to avoid surgery. IVF is also an option in women who have undergone tubal anastomosis, but who do not achieve pregnancy within 12 months.

The choice between IVF and tubal surgery is usually made based on relative success rates and the cost to the patients. If either IVF or surgery are covered completely or in part by insurance, the covered choice will usually see greater utilization.

Endometriosis

Endometriosis is a common cause of both infertility and pain (see Chapter 49). The effects of endometriosis on fertility can be decreased but not completely circumvented by the combination of gonadotropin stimulation and intrauterine insemination.¹⁴ The decrease in monthly fecundibility roughly correlates with the severity of disease, although there is a poor correlation between endometriosis stage and the chance of pregnancy after surgical treatment.¹⁵

In vitro fertilization is an effective treatment for infertile women with endometriosis who fail to conceive with less aggressive treatment. Some, but not all, studies suggest that endometriosis affects IVF success. Endometriosis has been implicated in poor ovarian reserve, poor quality of oocytes and embryos, and poor implantation.¹⁶^–²¹ Prolonged hormonal suppression using gonadotropin-releasing hormone (GnRH) analogues appears to improve IVF success in women with endometriosis.²²

Male Factor Infertility

At least 40% of men who are members of infertile couples have abnormal semen analyses.²³ Achieving pregnancy via conventional IVF in oligospermic men met with disappointing results largely due to fertilization failure.²⁴ The treatment of male infertility dramatically improved with the development of intracytoplasmic sperm injection (ICSI).²⁵ Injection of a single sperm into the egg appears to solve fertilization failure for the majority of male infertility problems. Currently, ICSI is used in about half of all ART treatment cycles. This technique is discussed in more detail in Chapter 39.

Antisperm Antibodies

Antisperm antibodies are a relatively uncommon and difficult to treat cause of infertility. IVF with ICSI has been found to be an effective treatment for women with antisperm antibodies, even in patients with a higher density of such antibodies.²⁶ In one study, patients with antisperm antibodies had a 32% clinical pregnancy rate after IVF with ICSI.²⁷ Because antisperm antibodies are relatively uncommon, it does not appear that routine screening for antisperm antibodies before IVF is cost-effective.²⁸

Unexplained Infertility

Up to 30% of infertile couples will have unexplained infertility.²⁹ Treatment options for unexplained infertility include ovarian stimulation with clomiphene citrate or gonadotropins, plus intrauterine insemination. IVF is an effective treatment for couples with unexplained infertility who fail to conceive with these approaches. The success of IVF in couples with unexplained infertility appears to be comparable to that achieved in cases of tubal damage or endometriosis.²⁴

Failure to Conceive After Ovulation Induction

Anovulatory women who fail to conceive with ovulation induction are good candidates for IVF. Unfortunately, the pregnancy rates after IVF are lower and the complication rates higher for patients with polycystic ovary syndrome (PCOS). In one study of 110 women with PCOS who underwent IVF/ICSI, women with a body mass index (BMI) greater than 29 kg/m² had a lower pregnancy rate per oocyte retrieval and a higher occurrence of ovarian hyperstimulation syndrome as compared to PCOS patients with a BMI of 29 kg/m² or lower.³⁰ Treatment with metformin to lower insulin levels in patients with PCOS undergoing IVF has been reported to improve success rates.³¹

Diethylstilbestrol Exposure

Women exposed in utero to diethylstilbestrol (DES) are known to have an increased risk of infertility.³² These women are also at increased risk of pregnancy complications as a result of reproductive tract abnormalities such as a T-shaped or hypoplastic cavity, a septate uterus, or uterine synechiae.³³ IVF outcomes in DES-exposed women are comparable with respect to ovarian response and embryo quality, but delivery rates are lower, possibly due to uterine abnormalities.³³

PATIENT SELECTION—PREDICTORS OF SUCCESS FOR IVF

In theory, only three things are needed to accomplish a successful IVF cycle: eggs, sperm, and a uterus into which the embryos are transferred. Although fertility testing is covered in Chapter 34 and Chapter 35, certain aspects of the evaluation specific to ART treatment follow.

Evaluation of the Uterus

Assessment of the uterine cavity is accomplished by transvaginal ultrasonography, hysteroscopy, or hysterosalpingography. Sensitivity of transvaginal ultrasonography to detect uterine abnormalities can be improved by instillation of fluid into the uterine cavity. Many programs perform transvaginal ultrasonography on all patients just before the start of an IVF cycle to ensure that no uterine abnormalities have recently developed.

Endometrial Polyps

Endometrial polyps, benign localized overgrowths of endometrial tissue of uncertain etiology, are present in up to 10% of asymptomatic premenopausal women over age 30.³⁴ It is assumed that endometrial polyps decrease fertility. For this reason, all large polyps are removed prior to IVF.

For smaller polyps that first appear during ovarian stimulation for IVF, optimal management remains to be determined. The problem is that removal requires interruption of the cycle and delay of IVF. A series of 49 women with endometrial polyps less than 2 cm in diameter who underwent IVF without removing the polyp found pregnancy and miscarriage rates were comparable to the general pregnancy rate of their IVF clinic population, although there was a trend toward a higher miscarriage rate.³⁵ At the present time, the decision to continue despite the polyp or stop the cycle and remove the polyp must be made on a case-by-case basis.

Hydrosalpinges

The presence of hydrosalpinges is well documented to decrease the success rate for IVF.³⁶ Whether pregnancy rates can be improved by salpingectomy remains less certain. A recent meta-analysis of three randomized, controlled trials indicated that the chance of live birth with IVF was doubled by pretreatment salpingectomy.¹² This effect seems to be most apparent in women with bilateral hydrosalpinges and with hydrosalpinges that are sonographically visible.³⁷ Drainage of hydrosalpinges at the time of egg retrieval can be performed, but it is uncertain if this improves IVF pregnancy rates. At present, many IVF programs offer patients with a sonographically visible hydrosalpinx the option of pretreatment salpingectomy.

Evaluation of the Ovaries

Determining the capacity of the ovaries to respond to ovarian stimulation is an important part of determining patient suitability for assisted reproduction. Age of the patient remains the most powerful predictor of ovarian response. However, a variety of hormonal and sonographic indices of ovarian reserve are also available.

Age

It has long been known that reproductive capacity declines with increasing age.³⁸ The age-dependent decline in female fertility can be partly attributed to the fact that women have a finite and nonreplenishable number of germ cells. The peak number of germ cells occurs at midgestation during fetal life and declines continuously thereafter, with an accelerated loss of oocytes between ages 37 and 38.³⁹ Diminished ovarian reserve is a term used to indicate decline in reproductive capacity associated with ovarian follicular depletion and diminished oocyte quality.

The success of IVF declines with age in a similar fashion (Fig. 38-1). For women undergoing IVF, diminished ovarian reserve is associated with poor ovarian response to gonadotropins, cycle cancellation, and lower chances of conception. Despite the known correlation with chronologic age and ovarian reserve, there exists a tremendous amount of variability in patients. As a result, multiple markers of ovarian reserve have been sought to supplement age as a predictor of ovarian response to stimulation in IVF. Timely recognition of reduced ovarian reserve is important for counseling patients prior to IVF.

Figure 38-1 Live birth rates per cycle start by age of the woman, for cycles performed in the United States in the year 2003

(From Centers for Disease Control and Prevention: 2003 Assisted Reproductive Technology Success Rates. Available at: http://www.cdc.gov/reproductivehealth/ART/index.htm. Accessed 17 September 2005.

Basal FSH

Measurement of serum follicle-stimulating hormone (FSH) in the early follicular phase of the menstrual cycle (day 3) is widely employed to assess the potential responsiveness of the ovaries to stimulation and can predict to some degree subsequent IVF pregnancy rates. This measurement of “basal” FSH is relatively inexpensive and easily obtained. However, the ideal way to use basal FSH levels for counseling prior to IVF remains controversial.

A direct correlation of the basal FSH and IVF outcome measurements was found in a study of 441 patients undergoing 758 consecutive IVF cycles.⁴⁰ Patients with basal FSH levels greater than 25 mIU/mL had only a 3.6% ongoing pregnancy rate, whereas those with basal FSH levels less than 15 mIU/mL had a 17% pregnancy rate. They also noted that fewer follicles were aspirated, fewer oocytes were obtained, and fewer embryos were available for transfer in the high FSH group compared to the low FSH group.

A recent meta-analysis of 21 studies indicated that basal FSH levels were moderately predictive for poor response but poorly predictive for pregnancy. In women over age 40, neither the basal nor the stimulated (clomiphene citrate challenge test [CCCT]) FSH level were able to predict pregnancy rates with IVF. However, no patient with a basal FSH level greater than 11.1 mIU/mL or a CCCT FSH greater than 13.5 mIU/mL (i.e., day 10 serum FSH) carried a pregnancy past 20 weeks.

Many IVF programs use a cut-off value for the basal FSH to determine when to cancel an IVF cycle. A study of 230 consecutive IVF cycles using GnRH antagonists found that the 97.5th percentile predictive value of basal FSH resulting in pregnancy was 10 mIU/mL. Patients should be counseled that these data suggest that pregnancy with IVF is unlikely in patients with basal FSH levels above this cutoff.

However, it is important to note that FSH has a wide fluctuation both between cycles in the same patients as well as between particular hormonal assays. It is therefore critical for each program to evaluate its own normative data for this assay as well as consider repetition of borderline hormonal values in patients.

Clomiphene Citrate Challenge Test

The CCCT decribed by Navot and colleagues is a method to dynamically elucidate the ovarian response.⁴⁸ The test is performed by measuring basal FSH on day 3 (day 2 is acceptable), administering clomiphene citrate (100 mg, days 5 to 9), and then remeasuring a FSH on day 10 (days 9 and 11 are also acceptable). An abnormal test was originally defined as an FSH level after clomiphene citrate more than 2 standard deviations from the basal level. Many clinicians define an abnormal CCCT as an FSH value greater than 12 mIU/mL on either cycle day 3 or 10.

The CCCT has been shown to have a sensitivity of 43% and a specificity of 76%, using IVF cycle cancellation as an endpoint in a study of 198 women.⁴⁹ Positive and negative predictive values were 37% and 80%, respectively. The estradiol levels during ovarian stimulation, the number of retrieved oocytes, and the rate of transfer cycles were significantly lower in patients with an abnormal CCCT. Forty-three percent of the abnormal test results were abnormal only on their elevation of day 10 or 11 FSH and not on their basal FSH level. However, the rate of pregnancies per started cycle did not show a statistically significant difference, which was attributed to the low numbers of patients.

A recent meta-analysis of a total of 1352 patients from 12 studies on basal FSH and 7 studies on CCCT found that basal FSH had a sensitivity of 6.6% and a specificity of 99.6% for identifying inability to achieve pregnancy in an IVF cycle, whereas CCCT sensitivity was 25.9% and specificity was 98.1%.⁵⁰ This study suggests that basal FSH and CCCT are similar in the ability to predict a clinical pregnancy and that, although a normal test is not helpful, an abnormal test is highly predictive that pregnancy will not occur with IVF. Based on this, the authors recommended that basal FSH be used rather than CCCT because of its simplicity and lower cost.

Combining Screening Markers

It is apparent that there are clear limitations to each of the proposed markers for ovarian response to stimulation. Therefore, attempts have been made to combine some of these markers to improve the predictive ability compared to a single marker alone. When basal FSH and estradiol are combined for patients undergoing IVF cycles, one study reported no pregnancies in patients with basal FSH levels greater than 17 mIU/mL and basal estradiol level greater than 45 pg/mL.⁴¹ Another study of 74 IVF patients with basal FSH levels less than 15 mIU/mL examined the ratio of basal FSH to LH.⁵¹ This study found that an elevated FSH-to-LH ratio greater than 3.6 correlated with a lower day 8 estradiol, lower peak estradiol, and fewer follicles greater than 15 mm in size

A randomized study of 110 patients evaluated multiple markers for ovarian reserve, including the exogenous FSH ovarian reserve test. This test involves the administration of 300 IU of rFSH (Gonal-F) on cycle day 3 with serum measurements of FSH, estradiol, and inhibin B before and 24 hours after administration. They concluded that the exogenous FSH ovarian reserve test was better than the CCCT at predicting the number of large follicles resulting from controlled ovarian hyperstimulation.⁵²

Conclusion

At present, basal FSH screening remains the screening tool of choice in many IVF centers in the United States. Issues examining different assay standards, variation by laboratory, and cycle-to-cycle variability of any biomarker of ovarian reserve will have to be addressed. Perhaps the most important aspect of ovarian reserve testing is the way in which this information is used to counsel the infertile couple. None of these tests have absolute sensitivity or specificity; however, the counseling of patients with abnormal tests to consider other options of treatment such as oocyte donation or adoption remains reasonable. Moreover, none of the data presented here indicates the ability of a single or even multiple tests to accurately exclude patients from treatment. The ultimate decision about the treatment course planned should be an individualized process between the infertile woman or couple and the physician.

OVARIAN STIMULATION FOR IVF

As noted above, the first successful human IVF cycle utilized a natural menstrual cycle. However, subsequent investigators found that much higher pregnancy rates could be achieved if ovarian stimulation was utilized. Monitoring the response to ovarian stimulation is accomplished with a combination of transvaginal ultrasonography and serum estradiol levels. Some programs also monitor serum progesterone and LH levels, although the utility of this additional monitoring is believed to be limited in modern stimulation protocols.

Clomiphene Citrate

Wood and colleagues were the first to report that administration of clomiphene citrate followed by human chorionic gonadotropin (hCG) to complete oocyte maturation both increased IVF success rates and improved scheduling efficiency for egg retrieval.⁵³ Clomiphene citrate was commonly used by early IVF programs in the United States until higher success rates were reported using human menopausal gonadotropins.

Clomiphene citrate is used at an oral dose of 50 to 150 mg/day for 5 days beginning on day 2 or 3 of the menstrual cycle, and hCG (5,000 to 10,000 units intramuscular) is given when the lead follicle reaches 18 mm in diameter. Although gonadotropins remain the standard ovarian stimulants for IVF, the convenience and low cost of clomiphene has caused it to be reconsidered as an option for good-prognosis IVF patients.⁵⁴^–⁵⁶

Gonadotropins

The use of the injectable gonadotropin FSH, with or without LH, circumvents the natural decline of FSH that occurs with development of the dominant follicle. In effect this rescues oocytes that would be physiologically lost to atresia in a natural cycle, which selects only one dominant follicle. Initial reports in the United States using human menopausal gonadotropins (a combination of FSH and LH) for IVF were considered spectacular, with pregnancies achieved in 5 of 24 laparoscopic egg retrievals (21%), at a time when IVF pregnancy rates after other stimulation protocols were less than 10%.⁵⁷ Although initial success likely was due in part to improvements in laboratory techniques and patient selection, gonadotropin injections soon became the standard treatment to prepare women for egg retrieval.

Human chorionic gonadotropin 5,000 to 10,000 units is typically used to mimic the LH surge and complete oocyte maturation in gonadotropin cycles. Egg retrieval is performed 34 to 36 hours after the hCG injection. Urinary and recombinant hCG products appear to give equivalent results.⁵⁸

Early preparations of human menopausal gonadotropins contained roughly equal amounts of FSH and LH. These preparations were extracted from the urine of postmenopausal women and also contained substantial amounts of urinary albumin and globulins. More recently, recombinant FSH and LH has become commercially available.

There has been much investigation and discussion of the relative merits of different gonadotropin preparations.^59,⁶⁰ Most programs in the United States have gravitated to some combination of FSH and LH for ovarian stimulation, along with a GnRH analogue. Recombinant and urinary FSH products seem to give equivalent pregnancy rates.⁶¹ Adjunctive stimulation with clomiphene in gonadotropin cycles, while lowering total gonadotropin doses required, has fallen out of favor because of the risk of spontaneous ovulation.

Gonadotropin-Releasing Hormone Agonists

In the early years of IVF, more than one quarter of stimulation cycles did not reach the stage of egg retrieval, primarily due to a premature LH surge.⁶² Long-term administration of GnRH agonists initially stimulates LH and FSH release, referred to as a flare or agonist phase. This is followed within 2 weeks by suppression of gonadotropin levels. This effect has been exploited for more than 20 years in IVF cycles.⁶³ Initially this drug was reserved for patients who demonstrated a premature LH surge, but its popularity surged when high pregnancy rates were documented with routine use.⁶⁴

In the United States, the most popular GnRH agonist is leuprolide acetate, given subcutaneously at doses of 0.25–1.0 mg/day. The routine use of GnRH agonists improves IVF success by reducing the rate of cycle cancellation, but the chance of pregnancy per embryo transfer is also increased, probably because more eggs are obtained, hence giving a larger selection of embryos for transfer.⁶⁵

Long Protocol

GnRH agonists are typically administered in a “long” protocol, whereby the flare and down-regulation occur before gonadotropins are begun. The agonist is typically started in the midluteal phase, or just after menses in anovulatory women. Pituitary down-regulation is confirmed after the onset of menstrual bleeding by a serum estradiol level 1 to 2 weeks after initiation of the drug, and gonadotropins are begun thereafter. Some programs simply use the appearance of a menstrual bleed as a sign that estradiol levels are suppressed.

Many programs prescribe a birth control pill for 1 or 2 months before starting the GnRH agonists. This helps schedule a series of patients and may facilitate pituitary down-regulation and prevention of ovarian cysts that may develop on the agonist.

Flare Protocol

Alternatively, the agonist can be given in the early follicular phase along with or just before initiation of gonadotropins. Use of a GnRH agonist flare protocol reduces the gonadotropin dose required to achieve follicular development, and this feature is particularly appealing for patients who have a poor response to gonadotropins. However, pregnancy rates in poor responders using the long and short GnRH agonist protocols seem to be equivalent.⁶⁶ One study found that routine use of the GnRH agonist flare protocol resulted in lower pregnancy rates compared to the long protocol, possibly because stimulation of LH during the follicular phase may impair normal oocyte maturation.⁶⁷

Gonadotropin-Releasing Hormone Antagonists

Antagonists of GnRH have recently become commercially available for clinical use. Earlier antagonists were associated with severe histamine release with local and systemic side effects. Histamine release does not seem to be a problem with the newer antagonists, ganirelix and cetrorelix. The advantage of these drugs is the absence of a gonadotropin flare when the drugs are started in the follicular phase. A recent multicenter IVF trial compared the GnRH antagonist ganirelix acetate with a long protocol using a GnRH agonist, leuprolide.⁶⁸ In this study, GnRH analogue administration was required for only 4 days on average using the GnRH antagonist compared to 19 days with the GnRH agonist. However, fewer eggs were obtained in the GnRH antagonist group.

The dose of GnRH antagonist administered affects IVF success. Excessive or insufficient suppression of LH and progesterone levels with GnRH antagonist decreases clinical pregnancy rates.⁶⁹ In poor-responder IVF patients, a protocol using GnRH antagonist is associated with lower pregnancy rates than the GnRH agonist flare protocol.⁷⁰ In a meta-analysis of five randomized, controlled IVF trials of GnRH antagonist versus GnRH agonist protocols, antagonist protocols were associated with a lower clinical pregnancy rate.⁷¹ It is possible that the lack of experience with the antagonists may explain this difference. Given the potential advantages of GnRH antagonists over agonists for IVF, protocols using these drugs will continue to be investigated.

Natural-Cycle IVF

IVF only became clinically useful after the development of methods to obtain mature eggs that could be reliably fertilized in vitro. Nevertheless, the complications and expense of ovarian stimulation are often treatment barriers for many women, especially for those with poor or exaggerated responses and those desiring egg retrieval to preserve fertility before cancer treatment. Although IVF programs have periodically reassessed the feasibility of natural-cycle IVF, the vast majority of IVF cycles continue to be performed in stimulated cycles because of higher efficiency and success rates.⁷²^–⁷⁴ Recently, the possibility of harvesting multiple immature eggs in a spontaneous menstrual cycle has been proposed to overcome some of the limitations of natural-cycle IVF.

In Vitro Maturation

Mammalian oocytes are maintained in meiotic arrest throughout most of follicular development; the resumption of meiosis I is induced by the preovulatory LH surge, which is emulated during an IVF cycle by intramuscular administration of hCG. Although the precise mechanisms that regulate the control of oocyte maturation remain obscure, it has been recognized for more than 70 years that immature oocytes liberated from antral follicles undergo spontaneous maturation in culture, termed in vitro maturation, without the need for hormonal stimulation.⁷⁵

Unfortunately, oocytes matured in vitro have a reduced ability to produce embryos that result in live offspring.

Immature oocytes are typically obtained in the mid- to late follicular phase of the menstrual cycle. Administration of hCG 36 hours before egg collection appears to facilitate oocyte maturation.⁷⁶ Because oocytes that have undergone in vitro maturation have a decreased IVF rate, ICSI is routinely performed on these oocytes. If embryos are transferred back to the patient in the same cycle, endometrial preparation with estradiol and progesterone is required.

To date, in vitro maturation has been most successfully employed in young women with multiple antral follicles, who typically have a high chance of pregnancy with conventional IVF. Despite this selection bias, IVF pregnancy rates are substantially lower than in stimulated cycles.⁷⁷ However, in cancer patients, where the time and hormonal milieu associated with the traditional IVF cycle may adversely affect the patient’s survival, there may be some advantage to the in vitro maturation technique. Likewise, patients with PCOS who undergo ovarian hyperstimulation with ovulation induction agents may be candidates for in vitro maturation.

MONITORING OVARIAN STIMULATION

The goal of ovarian stimulation for IVF is to stimulate the development of multiple follicles containing mature oocytes. Improved timing for hCG administration and subsequent oocyte retrieval has been an important factor in the improvement of IVF pregnancy rates. Initially, timing for IVF was determined by measuring estradiol levels in urine or serum. Unfortunately, estradiol monitoring alone cannot distinguish between the development of a single preovulatory follicle or multiple immature follicles. Fortunately, follicle size does correlate with oocyte maturity. When ultrasonography, first abdominally and then vaginally, was used to monitor ovulation induction, IVF pregnancy rates improved. By the time IVF became widely available clinically, the use of vaginal sonography as an adjunct to gonadotropin stimulation was well established.

Ultrasonographic Monitoring

In spontaneous cycles, maximal preovulatory follicle diameter is typically 20 to 24 mm. However, early work with gonadotropin ovulation induction for IVF suggested that pregnancy could be achieved if hCG was given when the lead follicle was as small as 14 mm. Initially, there was much confusion as to the optimal follicle size for hCG administration in IVF cycles, in part because of differences in equipment sensitivity and measurement techniques. Early published recommendations for hCG timing ranged from 12 mm to 20 mm diameter for the lead follicle. Many centers today administer hCG when at least two follicles have achieved a mean diameter of 18 mm. In IVF cycles with high estradiol levels (greater than 3000 pg/mL), 16 mm diameter for the lead follicle is used as the criteria for hCG administration to limit the risk of ovarian hyperstimulation. In patients with a low response to gonadotropins, a 20 mm diameter for the lead follicle is often used to allow the maturation of subordinate follicles without sacrificing the lead follicle to postmaturity. Cycles in which only one or two mature follicles develop are usually canceled.

Follicle diameters are determined by averaging either two or three dimensions to account for the irregular follicle shape often seen in stimulated cycles as a result of crowding of multiple follicles in the ovarian cortex. Using the average of two dimensions has been shown to correlate well with the follicular volume unless the follicle shape is predominantly ellipsoid. In these cases, the average of three dimensions might be a better reflection of volume. Three-dimensional ultrasonography and power Doppler angiography can be used to monitor IVF cycles, although the clinical usefulness of these techniques is still under investigation.

Endometrial Monitoring

The uterus undergoes characteristic sonographic changes during follicular development. As estradiol levels increase, the endometrium thickens, with a trilaminar pattern typically seen late in the follicular phase. Predicting the chance of pregnancy in a treatment cycle by sonographic examination of the endometrium has been an enticing goal for IVF practitioners.

Endometrial Thickness

Periovulatory endometrial thickness, determined by measuring both the anterior and posterior endometrium, has been shown to be greater in IVF cycles that resulted in conception.⁷⁸ Studies suggest that pregnancy after IVF appears to be most likely in patients with an endometrial thickness of 9 to 12 mm on the day of hCG administration and may be reduced with endometrial thickness greater than this.

Whether a minimal endometrial thickness is required to achieve pregnancy remains uncertain. Although pregnancies are less common when the endometrial thickness is less than 8 mm, pregnancies have been reported with an endometrial thickness as little as 4 mm. The reason for this wide range is unclear, because the mean interobserver variation of endometrial stripe measurement is only 1 mm.

Endometrial Pattern

Smith and colleagues ⁷⁹ described several ultrasonic endometrial patterns developing during ovarian stimulation for IVF. Two periovulatory endometrial patterns can be consistently recognized by high-resolution sonography: (1) a hypoechoic pattern, usually with a trilaminar appearance, and (2) a homogeneous, hyperechoic pattern.⁷⁹ Some studies have reported that the pregnancy rates of IVF patients with hyperechoic endometrium are lower than that obtained when a trilaminar or homogeneous hypoechoic pattern is observed, although other studies have failed to confirm this observation.

It has been speculated that the endometrial patterns seen by ultrasound are a reflection of changes in uterine blood flow. In a color flow Doppler study of 96 IVF cycles, 24% of women with hyperechoic endometrium had no subendometrial blood flow, compared to only 4% of women with a trilaminar endometrial pattern.⁸⁰ In this study, none of eight patients with undetectable endometrial blood flow conceived. In a study of subendometrial blood flow index just prior to ovarian stimulation for IVF, Doppler sonography of the spiral or uterine arteries did not predict subsequent IVF cycle outcome.⁸¹

Treatment of Abnormal Endometrial Vascularity

If poor endometrial development is somehow related to IVF failure, can something be done to improve uterine vascularity? In a small study of oocyte donor recipients who had failed to develop an endometrial thickness of at least 8 mm in a previous evaluation cycle, patients were randomly assigned to receive low-dose aspirin (81 mg/day) or no treatment. Aspirin treatment did not increase endometrial thickness. However, women whose endometrial thickness in the final treatment cycle was 8 mm or more were much more likely to conceive if they had received aspirin.

Aspirin has been proposed as an adjunct to ovarian stimulation for IVF, with one report of improved ovarian and uterine blood flow and increased pregnancy rates with its administration during gonadotropin treatment.⁸² However, two large trials failed to confirm any of these beneficial effects.^83,⁸⁴

It has been hypothesized that uterine artery blood flow could be increased by the administration of sildenafil (Viagra), a type 5-specific phosphodiesterase inhibitor that relaxes vascular smooth muscle. Although a small IVF series suggested that the chances of pregnancy could be dramatically increased by administration of vaginal sildenafil before and during ovarian stimulation, a subsequent randomized, controlled trial failed to show any effect of sildenafil on endometrial thickness or uterine blood flow.⁸⁵

Estradiol Monitoring

Estradiol monitoring during ovarian stimulation for IVF has not been found to be useful for timing of the hCG injection, but does appear useful in adjusting the dose of gonadotropin and for predicting the risk of ovarian hyperstimulation. Part of the art of IVF is knowing when to adjust gonadotropin levels up or down or cancel cycles based on number of follicles and estradiol levels. Although exact guidelines vary widely from center to center, many patients will cancel an IVF cycle if the estradiol levels do not reach 300 pg/mL by day 8 of stimulation. After this point, the dose of gonadotropin is usually not changed if the estradiol levels rise between 50% and 100% every 48 hours. The risk of severe hyperstimulation increases if the estradiol levels are greater than 3800 pg/mL at the time of hCG injection in women with polycystic ovaries or greater than 2400 pg/mL for women with hypothalamic amenorrhea.

OOCYTE RETRIEVAL

Retrieval Techniques

Retrieval of oocytes is generally performed 34 to 36 hours after administration of hCG to allow adequate oocyte maturation and avoid ovulation. As noted above, laparoscopy was initially used for oocyte retrieval. This technique required that the ovaries could be visualized laparoscopically, and some IVF programs would perform a “screening” laparoscopy some time before the IVF cycle to confirm ovarian accessibility. Subsequently, ultrasound-guided retrieval techniques were developed, which allowed retrieval of oocytes without the need for general anesthesia or direct visualization of the ovaries. Although transabdominal or periurethral oocyte retrievals have been performed in the past, the transvaginal egg retrieval has come to be the standard technique for egg retrieval in virtually all IVF programs.

Transvaginal egg retrieval employs a needle guide mounted atop a high-frequency endovaginal ultrasound probe (Fig. 38-2). The room setup for a typical IVF oocyte retrieval procedure is quite minimal (Fig. 38-3). The patient is placed in the dorsal lithotomy position, and the perineum and vagina are irrigated with sterile saline solution. Some programs precede this with an antiseptic cleanser, although IVF outcomes may be compromised by antiseptic contamination.⁸⁶ A broad-spectrum antibiotic is frequently given IV or by mouth before the egg retrieval; for example, oral doxycycline 100 mg daily for four days starting on the day of the retrieval. Pelvic infections are uncommon, but patients with endometriomas may be at higher risk despite the use of perioperative antibiotics.⁸⁷

Figure 38-2 Transvaginal probe set for oocyte retrieval. The probe is covered with a sterile glove and stockinette. Specific probe sheaths are also commercially available.

Figure 38-3 Procedure room for transvaginal egg retrieval. A foot-actuated vacuum pump is used to obtain the follicle aspirates, and a warming table keeps the follicle aspirates warm during the procedure.

Anesthesia

A variety of anesthetic techniques have been reported for transvaginal egg retrievals, including local, epidural, spinal, or general anesthetics, but many programs use IV sedation/analgesia.⁸⁸ Typically, a short-acting analgesic such as fentanyl is used in conjunction with a benzodiazepine or propofol.⁸⁹ Supplemental oxygen may be administered by mask or nasal cannula as needed. No clear relationship has been confirmed between IVF outcome and the choice of anesthestic technique for transvaginal egg retrieval, although general anesthesia has been reported to decrease IVF pregnancy rates.⁸⁸

EMBRYO TRANSFER

The critical part between oocyte retrieval and embryo transfer occurs in an embryology laboratory (see Chapter 39). The patient is called the day after the retrieval and told how many oocytes fertilized (Fig. 38-4). Embryos may be transferred into the uterus anytime during preimplantation development. The first successful IVF pregnancy occurred after transfer of a single blastocyst, but clinicians unable to duplicate this success turned to the transfer of embryos on day 2 or 3 after retrieval to overcome the limitations of their culture systems. At present, most IVF programs in the United States transfer embryos on day 3 after oocyte retrieval, but embryo transfers done on day 2 appear to give comparable results^2,⁹⁰ (Fig. 38-5). Pregnancy can occur when the fertilized egg is transferred to the uterus 1 day after fertilization.

Figure 38-4 Fertilized egg obtained via in vitro fertilization. The round structures within the cytoplasm are the pronuclei.

Figure 38-5 Two embryos on day 3 of development. The cell membranes are becoming indistinct as compaction occurs. These embryos were transferred and resulted in a singleton pregnancy.

With the increasing availability of high-quality commercially produced IVF culture media, the transfer of one or two embryos on day 5 or 6 after fertilization (at the blastocyst stage) has been proposed as a way of minimizing the risk of high-order multiple pregnancy while maintaining satisfactory pregnancy rates. Blastocyst transfer has several potential advantages: (1) delaying the embryo transfer to day 5 or 6 after fertilization allows for more detailed examination of embryo morphology (Fig. 38-6); (2) the embryonic genome is activated after about 2 days of development, and prolonged culture facilitates selection of the most robust embryos; (3) preimplantation embryos do not reach the uterine cavity until day 4 or 5 in vivo.⁹¹ The uterus provides a different nutritional milieu from the oviduct, and it has been postulated that the transfer of day 2 or 3 embryos to the uterine cavity may reduce their potential for implantation.⁹²

Figure 38-6 Expanded blastocyst on day 5 of development. The inner cell mass (which ultimately develops into the fetus) is apparent.

However, prolonged culture of embryos may decrease their capacity to develop and implant. Depending on embryo quality and culture conditions, in some IVF cycles few or no embryos may reach the blastocyst stage, resulting in few or no embryos to transfer or cryopreserve.⁹³ A recent meta-analysis of 16 randomized, controlled trials of day 2 or 3 versus day 5 or 6 embryo transfer found no significant differences in the rates of pregnancy, birth, multiple gestation, or high-order multiple gestation⁹⁴ (Table 38-1). Rates of embryo freezing per couple were significantly higher in day 2 or 3 transfers, and patients randomized to day 5 or 6 transfer were three times more likely to have no embryos to transfer. The results were similar in studies in which only patients with a favorable prognosis were enrolled. In studies where cumulative pregnancy rates for both fresh and frozen embryos were specified, pregnancies were more likely to occur in the day 2 or 3 group.

Table 38-1 Meta-analysis Results of Cleavage Stage Versus Blastocyst Transfer: Effect on Clinical Pregnancy Rates (Blake 2005)⁹⁴

Balancing the risks and benefits of multiple-embryo transfer remains one of the most vexing problems of ART. The transfer of more than one embryo increases the chance of pregnancy but also increases the risk of multiple gestations. The Society for Assisted Reproductive Technology recommends that no more than two embryos be transferred to women under age 35 who have a favorable prognosis for pregnancy.⁹⁵ A recent randomized, controlled trial of elective single-embryo versus double-embryo transfer suggested that comparable pregnancy rates could be achieved and multiple pregnancies avoided in young women with good embryo quality if embryo cryopreservation was routinely used for the second embryo.⁹⁶

Embryo Transfer Technique

Embryo transfers are performed in the dorsal lithotomy position. A speculum is inserted into the vagina, and the cervix is cleansed with culture medium or sterile saline solution. A trial transfer using an empty catheter is performed if not previously done, and the embryos are then transferred in a small volume (5 to 20 μL) of culture medium. A variety of embryo transfer catheter types are available, including rigid or soft, side- or end-loading, with or without an introducer. The chance of pregnancy with IVF is maximized if embryos are accurately and atraumatically placed within the uterus.

Ultrasound guidance for embryo transfer was first reported by Strickler and colleagues in 1985.⁹⁷ Since then, a number of retrospective studies have shown favorable effects on pregnancy rates when ultrasound was used to facilitate placement of the transfer in the uterine cavity. Recently, a randomized, controlled trial of ultrasound-assisted embryo transfer found that 50% of patients conceived in the ultrasound-guidance group, compared with only 34% of controls.⁹⁸

The beneficial effect of ultrasound guidance for embryo transfer may be due in part to the bladder filling required to perform the examination, which in itself has been shown to have a salutary effect on embryo transfer; however, transvaginal sonography guidance (without a full bladder) has also been shown to improve the success of embryo transfer. Although sonographically guided embryo transfer is still not done in all IVF programs, it may be particularly useful when the practice transfer is difficult, especially in cases in which soft catheters lacking tactile feedback are used.