The current challenges to efficient immature oocyte cryopreservation

Oocyte cryopreservation represents an important tool for assisted reproductive technology. It offers the opportunity to preserve fertility in women at risk of loss of the ovarian function for various pathologies. It also represents a treatment alternative for couples that cannot benefit from embryo cryopreservation because of moral, religious, or legal constrains. On the other hand, in vitro oocyte maturation has a range of applications. It can be applied in patients with a contraindication to ovarian stimulation to prevent ovarian hyperstimulation syndrome or to eliminate the risk of stimulation of hormone-sensitive tumours in cancer patients. However, while mature oocyte cryopreservation has found wide-spread application and oocyte in vitro maturation has a place for the treatment of specific clinical conditions, data on the efficiency of freezing of immature or in vitro matured oocytes are poorer. In this review we will focus on the combination of oocyte in vitro maturation with oocyte cryopreservation with particular emphasis on the biological implications of the cryopreservation of immature or in vitro matured oocytes. The two cryopreservation approaches, slow freezing and vitrification, will be discussed in relation to possible cryodamage occurring to subcellular structures of the oocyte and the functional interaction between oocyte and cumulus cells.     

Effects of Controlled Ovarian Hyperstimulation on Oocyte Quality in Terms of the Incidence of Apoptotic Granulosa Cells

Purpose: The aim was to investigate which ovarian hyperstimulation protocol performed in the same patients causes development of oocytes of good quality. Methods: Twenty normo-ovulatory women underwent three different controlled ovarian hyperstimulation protocols for in vitro fertilization–embryo transfer. Patients underwent follicle aspiration after administration of human chorionic gonadotropin (hCG). The total number of retrieved oocytes, the number of mature oocytes, and the rate of mature oocytes were examined. Recovered granulosa cells were stained with Hoechst 33258 and examined by fluorescence microscopy to estimate the incidence of apoptotic cells. Results: The total number of oocytes and the number of mature oocytes in gonadotropin-releasing hormone agonist (GnRHa) + human menopausal gonadotropin (hMG) + hCG and hMG + hCG cycles were higher than those in the natural cycle (P < 0.0001). The rate of mature oocytes in hMG + hCG cycle was the highest among the three protocols (P < 0.04). In the mural granulosa cells, the incidence of apoptotic cells in the GnRHa + hMG + hCG cycle was significantly higher than those of the natural (P < 0.002) and hMG + hCG cycles (P = 0.0002). The incidence of apoptotic cumulus granulosa cells in the GnRHa + hMG + hCG cycle was significantly higher than those of natural and hMG + hCG cycles (P < 0.002). Moreover, the incidence of apoptotic cumulus granulosa cells in the hMG + hCG cycle was significantly lower than that in the natural cycle (P < 0.01). Conclusions: These results indicated that hMG + hCG is the most appropriate controlled ovarian hyperstimulation protocol among the three examined with regard to oocyte quality.     

Oocyte diameter predicts the maturation rate of human immature oocytes collected ex vivo

PurposeTo study the impact of oocyte diameter and cumulus cell mass on the potential for final maturation of immature human oocytes in vitro.MethodsImmature oocytes (n = 1563) from 75 women undergoing fertility preservation by ovarian tissue cryopreservation (14–41 years) were collected. After preparation of the ovarian cortex for freezing, immature oocytes were collected from the surplus medulla. After collection, IVM was performed according to standard published methods. The mass of cumulus cell surrounding the immature oocyte was grouped according to size. After IVM, each oocyte was photographed, measured, and the diameter was calculated as a mean of two perpendicular measurements.ResultsThe diameter of the oocytes ranged from 60 to 171 µm with a mean of 115 µm (SD:12.1) and an interquartile range from 107 to 124 µm. The oocyte diameter was positively associated with a higher incidence of MII (p < 0.001). MII oocytes had a significantly larger mean diameter than MI, GV, and degenerated oocytes. The size of the cumulus cell mass was significantly associated with the MII stage (p < 0.001) and larger oocyte diameter (p < 0.001). The results further confirm that the diameter of the fully grown oocyte is reached relatively early in human follicular development and that the factors governing oocyte maturation in vitro are connected to the surrounding cell mass and the oocyte.ConclusionThe diameter of the oocyte is a highly determining factor in the nuclear maturation of the human oocyte during in vitro maturation, and the size of the cumulus cell mass is closely positively associated with a larger diameter.     

人类不成熟卵母细胞体外成熟影响的因素初探

为研究在自然月经周期中获得的人类不成熟卵母细胞 -放射冠 -卵丘细胞复合体体外成熟培养条件 ,作者从手术切除的卵巢组织获取不成熟卵母细胞 -放射冠 -卵丘细胞复合体 ,分别置于 90 % Ham' F-1 0 + 1 0 %灭活人血清 + FSH+ h CG(模拟卵泡液 )与 5 0 %Ham' F-1 0 + 5 0 %人类成熟卵泡液中培养 48h。结果显示 ,卵母细胞 -放射冠 -卵丘细胞复合体在两种体外成熟培养基中培养 48h后 ,成熟率分别为 41 .8%和 2 1 .1 % ,两者之间存在统计学差异 (P<0 .0 5 )。作者还比较了在前一种培养基中卵母细胞 -放射冠 -卵丘细胞复合体和裸卵的体外成熟率 ,分别为 41 .8%和 7.6% ,两者间存在统计学差异 (P<0 .0 0 5 )。将获取的不成熟卵母细胞 -放射冠 -卵丘细胞复合体按供者年龄分成 2 5～ 3 5岁组和 3 6～46岁组 ,比较此两组卵母细胞在前一种培养基中成熟率 ,分别为 5 7.1 %和 2 5 .0 % ,两者间在统计学上有显著性差异 (P<0 .0 1 )。结果提示 :不成熟卵母细胞 -放射冠 -卵丘细胞复合体可在模拟卵泡液中培养成熟 ,优于 5 0 % Ham' F-1 0 + 5 0 %人类成熟卵泡液 ;卵丘细胞包裹对于卵母细胞体外成熟有重要作用 ;供卵者年龄可影响卵母细胞的体外成熟率。     

Successful birth after transfer of blastocysts derived from oocytes of unstimulated woman with regular menstrual cycle after IVM approach

Purpose : To report a delivery after transfer of blastocysts derived from eggs collected following in vivo HCG priming in a patient with regular menstrual cycles undergoing in vitro maturation (IVM) program. Methods : A woman had regular menstrual cycle and had experience of ovarian hyperstimulation syndrome (OHSS) during a previous conventional IVF-ET cycle. The patient was primed with 10,000 IU HCG 36 h before egg retrieval. After oocyte collection, the maturity of oocytes was evaluated and immature oocytes were cultured in IVM medium. The matured oocytes were fertilized with husband sperm, and normal fertilized eggs were cultured to blastocysts stage until embryo transfer in uteri. Results : Three MII-stage and 13 GV-stage oocytes were collected from the patient. Three mature oocytes were fertilized by conventional IVF. All three fertilized oocytes were developed to blastocysts. Immature oocytes were matured in vitro and insemination was carried out by ICSI. Out of eight fertilized zygotes, two developed to blastocyst stage. Transfer of three expanded blastocysts on Day 6 resulted in pregnancy in the patient and one healthy baby was born. Conclusions : This report provides an approach to treat infertile women with regular menstrual cycle and high risk of OHSS.     

Treatment variables in relation to oocyte maturation: Lessons from a clinical micromanipulation-assisted in vitro fertilization program

Objective: In an effort to understand the mechanism underlying the improved pregnancy rate observed in IVF cycles when gonadotropin-releasing hormone analogues (GnRH-a) are applied, we investigated a possible relationship between treatment variables and oocyte-nuclear maturity. Design: Nuclear maturity was retrospectively assessed in cumulus-free, denuded oocytes, obtained from women undergoing micromanipulation-assisted IVF treatment following controlled ovarian hyperstimulation with GnRH-a and menotropins. Setting: The setting was the infertility and IVF unit of a tertiary academic medical center. Participants: Two hundred twenty-one patients underwent 435 treatment cycles. Main Outcome Measure: This was the proportion of germinal vesicle-intact immature (GVII) oocytes. Results: One hundred fifty-four of the 3520 oocytes studied (4.4%) were in the GVII stage. These oocytes were found in 66 of the treatment cycles (15.2%) and in 54 of the patients (24.4%). Cycles in which GVII oocytes were detected did not differ from those in which all the aspirated oocytes were mature in the following respects: patient age, type and duration of infertility, controlled ovarian hyperstimulation protocol and time of ovum pickup. However, the GVII group was characterized by a significantly higher peak estradiol level, as well as a higher number of mature follicles visualized sonographically (diameter, >14 mm) and oocytes retrieved. Conclusions: Comparing the present findings with previously published data, it appears that the inclusion of GnRH-a in the stimulation regimen is associated with a lower proportion of immature oocytes. A higher occurrence of oocyte-nuclear immaturity is apparently associated with a significantly better ovarian response to stimulation. The high incidence of immature oocytes observed in patients with normospermic partners and low fertilization rates in previous cycles may suggest that the fertilization failure in some of these cases is due to oocyte, rather than sperm, dysfunction.     

Steroid-depleted polycystic ovarian syndrome serum promotes in vitro oocyte maturation and embryo development

In vitro maturation (IVM) of immature oocytes obtained from patients with polycystic ovarian syndrome (PCOS) is considered as a novel strategy in order to reduce clinical side effects and cost of in vitro fertilization (IVF) technique. The aim of this study was to evaluate the effects of PCOS whole and steroid-depleted serums on in vitro oocyte maturation indices. Patients with PCOS were selected according to the Rotterdam criteria. Cumulus–oocyte complexes and blood serums were collected and pooled. Cumulus cells and immature oocytes were treated with 10% whole or steroid-depleted serums. Stearoyl-CoA desaturase-1 (SCD1) and cyclooxygenase-2 (COX2) expression levels in cumulus cells were evaluated by quantitative PCR. Fatty acid composition of cumulus cells was analyzed using gas–liquid chromatography. Polar body observation was considered as the oocyte maturation index. Oleate (1.28-fold, p?=?.006), SCD1 expression (450-fold, p?=?.001), and COX2 expression (35-fold, p?=?.02) in cumulus cell, as well as oocyte maturation (p?in vitro embryo development (p?相似文献   

The Potential Use of Maturation In Vitro of Human Oocytes in Low Responder Patients

Purpose: To assess whether maturation in vitro of humanoocytes (MIVHO) could be an alternative treatment in lowresponders to ovarian stimulation for in vitro fertilization(IVF). Methods: Prospective case=ncontrol study. Spontaneouslyovulatory women who volunteered were included in ourprogram of MIVHO at the Instituto Valenciano deInfertilidad. Rates of oocyte retrieval, in vitro maturation,fertilization, and development up to the blastocyst stage werestudied. Results: A significantly increased rate of oocyte retrievalwas found when the pickup was performed before follicularselection. No differences were found when MIVHO was usedin a low responder patient with an ovarian content of earlyantral follicles > 5 as compared to normal responders. Conclusions: MIVHO could be a successful choice in lowresponder patients with an acceptable number of early antralfollicles. Oocyte retrieval should be performed beforefollicular selection in order to obtain more oocytes.     

In-vitro maturation of oocytes: biological aspects

Natural cycle and in-vitro maturation (IVM) of oocytes are becoming interesting alternatives to classical assisted reproduction technology approaches for patients, especially in those at high risk for ovarian hyperstimulation syndrome or with poor ovarian reserve. More than for their clinical and biological indications, natural cycle and IVM of oocytes can also be considered as good social and economic alternatives to the classical IVF treatment, based on their financial cost-effectiveness with exclusion of expensive medications. To be successful, IVM must entail both nuclear and cytoplasmic maturation, and its maturation and success rates are affected by the number of collected cumulus layers, the degree of atresia and the maturation rate between 24 and 48 h. Endogenous regulation of oocyte maturation is a complex sequence of events regulated by endocrine parameters, oocyte/follicular cross-talk, and intra-oocyte kinase/phosphatase interactions. This complex process requires a better definition of each contributing factor affecting oocyte development and the resulting embryo quality. The clinical aspects of IVM have been documented earlier; the present paper will mainly focus on the biological aspect of oocyte maturation in vitro and the quality of derived embryos.     

Oocyte maturation inhibitor activity in human follicular fluid: Quantitative determination in unstimulated and clomiphene citrate- and human menopausal gonadotropin-stimulated ovarian cycles

Since removal of the oocyte from the intrafollicular milieu allows meiotic resumption and germinal vesical breakdown to proceed, the concept of an intrafollicular oocyte maturation inhibitor (OMI) has evolved. Accordingly, we asked the following questions: Is there OMI activity in human follicular fluid? Does OMI activity change with ovarian hyperstimulation? and Does OMI activity correlate with oocyte fertilization or the concentration of steroids in the corresponding follicular fluid? Fresh cumulus enclosed porcine oocytes from small follicles were incubated with human follicular fluid aspirates from normally menstruating patients with or without treatment: unstimulated follicles (N=10), clomiphene citrate (150 mg/day) (N=10)-treated cycles, and human menopausal gonadotropin (hMG) (N=12)-treated cycles. A lyophylized porcine follicular fluid standard and serum-free culture media were used as positive and negative controls, respectively. After a 40-hr incubation with test materials, the oocytes were fixed, stained, and evaluated for oocyte maturation as determined by germinal vesical breakdown. Human follicular fluid, estradiol, progesterone, androstenedione, and testosterone levels were determined by radioimmunoassay. The 50% inhibitory dose (ID₅₀) for OMI activity in follicular fluid from untreated, spontaneously menstruating women was less than that for follicular fluid from clomiphene-stimulated patients, which was less than that for follicular fluid from hMG-stimulated patients. The difference between OMI values from untreated and hMG-stimulated follicular fluids was statistically significant. Human oocytes removed from follicular fluid with higher OMI activity tended not to fertilize in vitro compared to the relatively lower OMI activity present in follicular fluid yielding oocytes which did fertilize. However, these differences were not significant. Although there were no significant correlations between any of the follicular fluid concentrations of sex steroids and OMI activity, there was a trend toward higher androgen levels in follicular fluid with higher OMI activity. These findings lend support to the hypothesis that immature, nonfertilizable follicles obtained from spontaneously cycling women with or without exogenous gonadotropin treatment contain higher OMI activity levels than mature, fertilizable follicles.     

Retrieval, Maturation, and Fertilization of Immature Oocytes Obtained from Unstimulated Patients with Polycystic Ovary Syndrome

Purpose: Our purpose was to determine whether immature oocytes could be retrieved under local anesthesia, whether these oocytes would mature and fertilize in vitro, and whether adequate endometrium development could be obtained after hormonal supplementation. Methods: Ovum pick-up was performed under local anesthesia. Immature oocytes were cultured and inseminated. To prepare the endometrium, estradiolvalerate was administered in combination with micronized progesterone. Results: Immature oocytes were obtained in all cases. Fifty-six percent (n = 30) of the oocytes developed into metaphase II (MII) after 48 hr of culture, and another 20% reached the MII stage by 72 hr. Normal fertilization was observed in only 10% of oocytes inseminated. No embryonic development occurred, and therefore embryo transfer was not performed in any of the patients. Endometrial microbiopsy was performed in all subjects and endometrial development was considered sufficient in eight patients. Conclusions: We collected immature oocytes from patients with polycystic ovary syndrome without general anesthesia. In vitro maturation of these oocytes seemed adequate but fertilization rates were poor. Sufficient endometrial quality was obtained after hormonal substitution.     

Pregnancies and deliveries after transfer of human blastocysts derived from in vitro matured oocytes in in vitro maturation cycles

A total of 82 patients underwent 106 cycles in which immature oocytes were recovered after hCG priming and transferred at blastocyst-stage. After transfer, the implantation rate was 26.8%, and the clinical pregnancy rate was 51.9%. We found that the oocytes retrieved after hCG priming in women with high risk of ovarian hyperstimulation syndrome in the in vitro maturation program can develop to blastocyst, and pregnancies can be established by transfer of the blastocysts.     

Intracytoplasmic Sperm Injection After Follicle Stimulation with Highly Purified Human Follicle-Stimulating Hormone Compared with Human Menopausal Gonadotropin

Purpose: Our purpose was to compare oocyte nuclear maturation and embryo quality after pituitary down-regulation and ovarian stimulation with highly purified follicle-stimulating hormone (FSH) or human menopausal gonadotropin (HMG). Methods: Fifty-five patients 37 years of age or younger who were undergoing in vitro fertilization (IVF)–intracytoplasmic sperm injection (ICSI) were evaluated retrospectively. In all cases, male factor was the only indication for treatment, with no female-related factors identified. Following pituitary down-regulation, patients were stimulated with hMG (n = 20) or highly purified FSH (n = 35). Main outcome measures included ovarian response to stimulation, oocyte maturity, and ICSI fertilization results. Secondary outcome measures included pregnancy rates and outcome. Results: The ovarian response to stimulation was similar for the two groups, as were the percentage of metaphase II oocytes, fertilization and cleavage rates, and number and quality of transferred and cryopreserved embryos. Cycle outcome was comparable. Conclusions: In normogonadotropic subjects, monocomponent therapy with highly purified FSH is as effective as hMG in stimulating ovarian follicular development, synchronization of oocyte maturation, and IVF-ICSI outcome. Our findings support the conclusion that the luteinizing hormone component in the stimulation protocol is unnecessary.     

Follicle stimulating hormone effects on immature human oocytes: In vitro maturation and hormone production

Purpose: Our purpose was (1) to determine if in vitro maturation of unstimulated oocytes could be improved with the addition of urofollitropin; (2) to evaluate the output of estradiol, testosterone, progesterone, and androstenedione by the cultured oocyte-cumulus complex; and (3) to ascertain if steroid hormone production of the oocyte-cumulus complex correlates with final oocyte maturation stage. Methods: Fifty-eight immature oocytes were obtained from 11 regularly cycling women undergoing oophorectomy. The oocyte-cumulus complexes were randomly assigned to control medium (Ham’s F-10 supplemented with 7.5% fetal bovine serum) or test medium (control medium supplemented with 75 mIU/ml of urofollitropin). Results: (1) The addition of urofollitropin to oocyte culture medium does not significantly increase the ability of the oocyte to achieve the metaphase II stage; (2) the addition of urofollitropin significantly increases the production of progesterone, testosterone, and androstenedione by the oocyte-cumulus complex; and (3) there is no difference in the production of estradiol, progesterone, testosterone, and androstenedione by the oocyte-cumulus complex at the germinal vesicle, metaphase I or metaphase II stage of oocyte maturation. Conclusions: This information is of importance in the use of oophorectomy specimens for patients who must undergo an oophorectomy but desire to attempt pregnancy using their oocytes, in the use of oophorectomy specimens for donor oocytes, or for patients undergoing in vitro fertilization using immature oocyte collection.     

Correlation between human follicular diameter and oocyte outcomes in an ICSI program

Purpose: To determine the correlation between the follicular sizes and oocyte recovery, metaphase II oocyte recovery, fertilization rate and good embryo quality from mature and immature oocytes in an intracytoplasmic sperm injection (ICSI) program. Methods: 991 follicles obtained from 72 ICSI cycles were classified into three groups according to their diameters as measured by transvaginal ultrasound including group A (<10 mm), group B (10–14 mm), and group C (>14 mm). All obtained oocytes were classified according to their nuclear maturation: germinal vesicle (GV), metaphase I (MI) and metaphase II (MII). Mature oocytes underwent ICSI while immature oocytes were further cultured until maturity before ICSI was performed. The rates of fertilization and good quality embryos at day 3 were evaluated. Results: A progressive and significant increase in the rates of oocyte recovery and MII oocyte recovery were observed from group A follicles compared to the other groups (p < 0.001). The fertilization rate of mature and in vitro matured oocytes, as well as the rate of good quality embryos showed a tendency to increase from group A to group C follicles, but not significantly. The corresponding fertilization rates were 78 and 55.3% (p < 0.001) for mature and in vitro matured oocytes, respectively. Conclusion: Collection of oocytes from small follicles, especially with a mean diameter less than 10 mm, and in vitro maturation of immature oocytes before fertilization may allow the total number of good quality and transferable embryos to be increased.     

Resumption of meiosis-I tissue to enucleated preovulatory oocytes: a preliminary report

Purpose : Ovarian tissue banking may be the best strategy to preserve female fertility. But optimal method to obtain viable mature oocytes remains challenging. In order to bypass the long in vitro oocyte growth period, we developed this study to test whether reconstruction of thawed primordial oocytes with enucleated preovulatory germinal vesicle (GV) oocytes could induce dictyate nuclei to undergo chromosomal condensation and meiotic maturation. Methods : Isolated primordial oocytes from thawed mouse ovarian tissue were reconstructed with enucleated GV oocytes. After electrofusion and in vitro maturation, the reconstituted oocytes were assessed for first polar body extrusion, cytoskeleton configuration, and chromosome abnormalities. Results : Primordial oocytes from thawed ovarian tissue showed a high survival rate. Following transfer and electrofusion, they could be fused with enucleated GV oocytes (35.6%, 36/101) and extruded a first polar body (52.8%, 19/36). These mature oocytes showed a normal spindle configuration and chromosome number. Conclusions : We successfully established a mouse cell model to prove that omitting the whole growth and maturation period by transfer of primordial oocytes to developmentally older enucleated oocytes would bypass the long growth period required to the preovulatory stage. Polar body extrusion could also ensue after in vitro growth. This study provided an alternative approach for future investigations in oocyte maturation.     

State of the art in in-vitro oocyte maturation

PURPOSE OF REVIEW: The recovery of immature oocytes followed by in-vitro maturation (IVM) and in-vitro fertilization is an attractive alternative to conventional in-vitro fertilization treatment in which controlled ovarian stimulation with gonadotropins is used to increase the number of available oocytes and embryos. Significant progress has been made to improve pregnancy and implantation rates from in-vitro matured oocytes. This review summarizes current knowledge and achievements in human oocyte in-vitro maturation for clinical application, and will highlight recent advances reported in in-vitro maturation treatment. RECENT FINDINGS: It has been demonstrated that priming of ovarian immature oocytes with follicle-stimulating hormone or human chorionic gonadotropin prior to immature oocyte retrieval improves oocyte maturation rates and embryo quality as well as pregnancy rates in infertile women with polycystic ovaries or polycystic ovary syndrome. The size of follicles may be important for the subsequent embryonic development, but the developmental competence of oocytes derived from the small antral follicles is not adversely affected by the presence of a dominant follicle. However oocyte maturation in vitro is profoundly affected by culture conditions. Currently more than 300 healthy infants have been born following immature oocyte retrieval and in-vitro maturation. In general, the clinical pregnancy and implantation rates have reached 30-35% and 10-15% respectively in infertile women with polycystic ovaries or polycystic ovary syndrome. SUMMARY: In-vitro maturation treatment can now be offered as a successful option to infertile women with polycystic ovaries or polycystic ovary syndrome. It is possible to combine natural cycle in-vitro fertilization with immature oocyte retrieval followed by in-vitro maturation, and thus offer women with various causes of infertility reasonable pregnancy and implantation rates without recourse to ovarian stimulation. Further research remains to be done to address the mechanism of oocyte maturation in order to refine culture conditions and improve the implantation rate of oocytes matured in vitro.     

Guideline No. 315: Prevention of Ovarian Hyperstimulation Syndrome

Summary Statements

• 1.The particular follicle-stimulating hormone formulation used for ovarian stimulation does not affect the incidence of ovarian hyperstimulation syndrome. (I)
• 2.Coasting may reduce the incidence of severe ovarian hyperstimulation syndrome. (III)
• 3.Coasting for longer than 3 days reduces in vitro fertilization pregnancy rates. (II-2)
• 4.The use of either luteinizing hormone or human chorionic gonadotropin for final oocyte maturation does not influence the incidence of ovarian hyperstimulation syndrome. (I)
• 5.There is no clear published evidence that lowering the human chorionic gonadotropin dose will result in a decrease in the rate of ovarian hyperstimulation syndrome. (III)
• 6.Cabergoline starting from the day of human chorionic gonadotropin reduces the incidence of ovarian hyperstimulation syndrome in patients at higher risk and does not appear to lower in vitro fertilization pregnancy rates. (II-2)
• 7.Avoiding pregnancy by freezing all embryos will prevent severe prolonged ovarian hyperstimulation syndrome in patients at high risk. (II-2)
• 8.Pregnancy rates are not affected when using gonadotropin-releasing hormone (GnRH) agonists in GnRH antagonist protocols for final egg maturation when embryos are frozen by vitrification for later transfer. (II-2)

Recommendations

• 1.The addition of metformin should be considered in patients with polycystic ovarian syndrome who are undergoing in vitro fertilization because it may reduce the incidence of ovarian hyperstimulation syndrome. (I-A)
• 2.Gonadotropin dosing should be carefully individualized, taking into account the patient’s age, body mass, antral follicle count, and previous response to gonadotropins. (II-3B)
• 3.Cycle cancellation before administration of human chorionic gonadatropin is an effective strategy for the prevention of ovarian hyperstimulation syndrome, but the emotional and financial burden it imposes on patients should be considered before the cycle is cancelled. (III-C)
• 4.Gonadotropin-releasing hormone (GnRH) antagonist stimulation protocols are recommended in patients at high risk for ovarian hyperstimulation syndrome (OHSS). The risk of severe OHSS in patients on GnRH antagonist protocols who have a very robust ovarian stimulation response can be reduced by using a GnRH agonist as a substitute for human chorionic gonadotropin to trigger final oocyte maturation. (I-B)
• 5.A gonadotropin-releasing hormone (GnRH) antagonist protocol with a GnRH agonist trigger for final oocyte maturation is recommended for donor oocyte and fertility preservation cycles. (III-C)
• 6.Albumin or other plasma expanders at the time of egg retrieval are not recommended for the prevention of ovarian hyperstimulation syndrome. (I-E)
• 7.Elective single embryo transfer is recommended in patients at high risk for ovarian hyperstimulation syndrome. (III-C)
• 8.Progesterone, rather than human chorionic gonadotropin, should be used for luteal phase support. (I-A)
• 9.Outpatient culdocentesis should be considered for the prevention of disease progression in severe ovarian hyperstimulation syndrome. (II-2B)

     

Very high serum estradiol levels are not detrimental to clinical outcome of in vitro fertilization

The use of gonadotropin-releasing hormone agonists as adjuncts to ovulation induction for in vitro fertilization (IVF) has resulted in increases in oocyte recovery rates. Along with increased oocyte number, greatly increased estradiol (E2) levels have been found. We sought to determine the clinical effect of very high E2 levels on the outcome of IVF cycles. Estradiol levels were measured in 141 patients undergoing controlled ovarian hyperstimulation with leuprolide acetate and human menopausal gonadotropin for IVF. Whereas the number of oocytes recovered and fertilized and the number of embryos available for cryopreservation were directly proportional to the E2 level, the fertilization rate and embryo cleavage rates were unrelated to the E2 level. When the patients were grouped in thirds according to E2 levels, pregnancy rate (PR) was highest in the patients with the highest E2 levels (E2 greater than 2,777 pg/mL, PR = 37%). One mild, one moderate, and one severe case of ovarian hyperstimulation syndrome occurred in patients with E2 greater than or equal to 3,000 pg/mL (n = 21), but in general, high E2 levels were attained with few complications. We conclude that high E2 levels are not detrimental to the pregnancy outcome of IVF. Our experience further suggests that cycles with E2 levels of less than or equal to 5,000 pg/mL need not be canceled and can proceed to oocyte recovery and embryo transfer.     

Strategies in human in-vitro maturation and their clinical outcome

The basis of in-vitro maturation (IVM) is the maturing in vitro of oocytes from the germinal vesicle (GV) stage of development to the metaphase II stage. Experience in handling immature oocytes has been obtained from two main groups. The first group is women suffering from polycystic ovarian syndrome, who are extremely sensitive to stimulation with exogenous gonadotrophins in assisted reproduction, and have a significant risk of developing ovarian hyperstimulation syndrome (OHSS). The second group is regular cycling women with normal ovaries referred for IVF due to severe male infertility. In both groups, aspiration of immature oocytes has been performed in unstimulated cycles and after priming with human chorionic gonadotrophin or FSH respectively. Clinical pregnancy rates of 24% per aspiration have been obtained. Children born after IVM appear to be healthy. These data, taken together, suggest that in future, immature oocyte retrieval combined with IVM could replace conventional IVF in selected patients.