Ana Cobo

Use of cryo-banked oocytes in an ovum donation programme: a prospective, randomized, controlled, clinical trial

BACKGROUND An efficient oocyte cryopreservation method is mandatory to establish a successful egg-banking programme. Although there are increasing reports showing good clinical outcomes after oocyte cryopreservation, there is still a lack of large controlled studies evaluating the effectiveness of oocyte cryo-banking. In this study, we aimed to compare the outcome of vitrified-banked oocytes with the gold standard procedure of employing fresh oocytes. METHODS A randomized, prospective, triple-blind, single-centre, parallel-group controlled-clinical trial (NCT00785993), including 600 recipients (alpha = 0.05 and power of 80% for sample-size calculation) selected among 1032 eligible patients from November 2008 to September 2009, was designed to compare the outcome of vitrified-banked oocytes with the gold standard procedure of employing fresh oocytes. The study was designed to establish the superiority of the ongoing pregnancy rate (OPR) of fresh oocytes over that of vitrified oocytes, by performing a likelihood ratio test in a logistic regression analysis expressed as odds ratio (OR) with 95% confidence interval (CI). A limit of 0.66 for OR of vitrified versus fresh groups was defined to set up a possible conversion from superiority to non-inferiority. Randomization was performed 1:1 based on a computer randomization list in vitrification (n = 300) or fresh groups (n = 300). The primary end-point was the OPR per randomized patient i.e. intention-to-treat population (ITT). Secondary end-points were clinical pregnancy (CPR), implantation (IR) and fertilization rates, respectively. Additionally, embryo developmental characteristics were recorded. RESULTS There were no differences in donor ovarian stimulation parameters, demographic baseline characteristics for donors and recipients, ovum donation indications or male factor distribution between groups (NS). The OPR per ITT was 43.7 and 41.7% in the vitrification and fresh groups, respectively. The OR of OPR was 0.921 in favour of the vitrification group. Nevertheless, the 95% CI was 0.667-1.274, thus the superiority of fresh group with respect to OPR was not proven (P = 0.744). Non-inferiority of the vitrified group compared with the fresh group was shown with a margin of 0.667, which was above the pre-established non-inferiority limit of 0.66. CPR per cycle (50.2 versus 49.8%; P = 0.933) or per embryo-transfer (55.4 versus 55.6% ; P = 0.974), and IR (39.9 versus 40.9%; P = 0.745) were similar for patients receiving either vitrified or fresh oocytes. The proportion of top-quality embryos obtained either by inseminated oocyte (30.8 versus 30.8% for Day-2; and 36.1 versus 37.7% for Day-3, respectively) or by cleaved embryos (43.6 versus 43.8% for Day-2 and 58.4 versus 60.7% for Day-3, respectively) was similar between groups (NS). CONCLUSIONS This controlled-randomized, clinical trial confirmed the effectiveness of oocyte cryo-storage in an ovum donation programme, failing to demonstrate the superiority of using fresh oocytes with respect to the use of vitrified egg-banked ones in terms of OPR. Instead, the non-inferiority of vitrified oocytes was confirmed. These findings involve highly relevant issues that may open a new range of possibilities in ART.

Clinical application of oocyte vitrification: a systematic review and meta-analysis of randomized controlled trials

OBJECTIVE To perform a systematic review of the literature to identify randomized controlled trials assessing the efficacy of oocyte vitrification in terms of oocyte survival, fertilization, embryo development, and pregnancy rates. DESIGN Systematic review and meta-analysis of randomized controlled trials. SETTING Private university-affiliated IVF center, university-based hospital. PATIENT(S) Patients recruited in randomized controlled trials considering oocyte vitrification as one of the experimental arms and slow freezing or fresh oocytes control as the other. INTERVENTION(S) Vitrification of human oocytes vs. slow freezing or fresh oocytes. MAIN OUTCOME MEASURE(S) Ongoing pregnancy rate; secondary outcomes were clinical pregnancy rate, implantation rate, embryo development, fertilization rate, and oocyte survival. RESULT(S) Five eligible studies were finally included. They involved 4,282 vitrified oocytes, 3,524 fresh oocytes, and 361 slow-frozen oocytes between 2005 and 2009. The rates of ongoing pregnancy, top-quality embryo, embryo cleavage, and fertilization did not differ between the vitrification and the fresh oocyte groups. The oocyte survival rate was higher in vitrified vs. slow-frozen oocytes (odds ratio [OR] 2.46, 95% confidence interval [CI] 1.82-3.32), although heterogeneity between studies was observed. The fertilization rate was higher in vitrified vs. slow-frozen oocytes (OR 1.50, 95% CI 1.07-2.11). Vitrification also resulted in a higher rate top-quality embryo (22.4% vs. 8.0%, OR 3.32, 95% CI 1.37-8.02) and embryo cleavage rate (day 2: 64.6% vs. 47.7%, OR 2.00, 95% CI 1.33-3.00; day 3: 53.0% vs. 33.3%, OR 2.25, 95% CI 1.32-3.85) as compared with slow freezing. CONCLUSION(S) Vitrification is an efficient method to preserve oocytes, although more large controlled clinical trials are needed to strengthen this conclusion.

Twins born after transplantation of ovarian cortical tissue and oocyte vitrification

OBJECTIVE To present a combination of ovarian tissue and oocyte cryopreservation as an effective strategy for achieving pregnancy in a breast cancer patient. DESIGN Case report. SETTING Tertiary care university-affiliated hospital, tissue bank, and infertility clinic. PATIENT(S) A 36-year-old patient diagnosed with atypical medullar breast cancer and negative for estrogen, P, and HER2 receptors underwent ovarian tissue cryopreservation before receiving chemotherapy and radiotherapy. INTERVENTION(S) Laparoscopic ovarian cortex extraction, ovarian tissue cryopreservation, ovarian tissue thawing and transplantation, controlled ovarian stimulation (COS), oocyte retrieval, vitrification and IVF, and embryo culture and replacement. MAIN OUTCOME MEASURE(S) Resumption of spontaneous ovarian function after transplantation, response to COS, oocyte vitrification, IVF, pregnancy, and delivery. RESULT(S) Menses occurred 63 days after transplantation. Sixteen mature oocytes were obtained in four COS procedures. All vitrified oocytes survived warming, and 77.7% were fertilized. Two day 3 embryos were replaced, and two healthy boys were born at 34 weeks. CONCLUSION(S) Ovarian tissue cryopreservation and grafting preserves fertility. Simultaneous oocyte vitrification increases the success of assisted reproductive technology in poor-prognosis patients and avoids the consequences of the short lifespan of the transplanted tissue.

Consistent and predictable delivery rates after oocyte vitrification: an observational longitudinal cohort multicentric study

BACKGROUND An efficient method for cryopreservation of human oocytes may offer solutions to legal and ethical problems in routine infertility programs and may also be used for fertility preservation for medical and social reasons. METHODS We conducted an observational longitudinal cohort multicentric study to investigate the efficacy and reproducibility of oocyte cryopreservation outcomes in IVF/ICSI cycles. Moreover, the effects of patient and cycle characteristics on the delivery rate (DR) were analyzed. RESULTS In 486 cycles performed in 450 couples, 2721 oocytes were warmed and 2304 of them survived cryopreservation (84.7%). Of the 2182 oocytes subjected to ICSI, the rates of fertilization and development to top-quality embryos were 75.2 and 48.1%, respectively. A total of 128 deliveries were obtained (26.3% per cycle and 29.4% per transfer) for 450 patients (28.4%) and 147 babies were live born from 929 embryos transferred (15.8%). The forward logistic regression analysis on a per patient basis showed that female age [odds ratio (OR): 0.93, 95% confidence interval (CI): 0.88-0.98], number of vitrified oocytes (OR: 1.08, 95% CI: 1.01-1.17) and the day of transfer (OR: 1.97, 95% CI: 1.14-3.42) influenced DR. By recursive partitioning analysis, it can be estimated that more than eight oocytes vitrified are required to improve the outcome (22.6 versus 46.4% DR, respectively). When fewer oocytes are available in women aged >38 years, results are dramatically reduced (12.6 versus 27.5% DR, respectively). Conversely, when >8 oocytes are available, blastocyst culture represents the most efficient policy (62.1% DR; data from one center only). CONCLUSIONS Oocyte vitrification is an efficient and reliable approach, with consistent results between centers and predictable DRs. It should be applied routinely for various indications. A predictive model is proposed to help patient counselling and selection.

Use of fluorescence in situ hybridization to assess the chromosomal status of embryos obtained from cryopreserved oocytes.

OBJECTIVE To analyze the chromosomal status of human embryos obtained from frozen-thawed oocytes. DESIGN Fluorescence in situ hybridization analysis of embryos obtained after oocyte cryopreservation. SETTING Department of Obstetrics and Gynecology at the University of Perugia, Italy, and the Instituto Valenciano de Infertilidad, Spain. PATIENT(S) Oocyte donors (n = 43). Fertilization, development, and chromosomal status of the embryos were compared with a control group (n = 18) of patients undergoing preimplantation genetic diagnosis for sex chromosome-linked diseases. INTERVENTION(S) Collection of oocytes after conventional ovarian stimulation and cryopreservation using propanediol as the cryoprotectant and a slow freezing procedure. Microinjection of surviving metaphase II oocytes and evaluation of fertilization and embryo development up to blastocyst stage. Chromosomal analysis after embryo biopsy. MAIN OUTCOME MEASURE(S) Survival, fertilization, and blastocyst rates. Embryo chromosomal analysis employing specific probes for chromosomes 13,18,21, X and Y. RESULT(S) The overall survival rate was 59.4%. There was no difference between cryopreservation and control groups in fertilization rates (76.5% vs. 90.5%) or blastocyst development (29.6% vs. 35%). The percentage of blastocysts from the original number of cryopreserved oocytes was only 5.6%, comparable to the 5.9% obtained in the control group. The percentage of embryos with abnormal number of chromosomes in the cryopreservation group (28.6%) was comparable to the 26% observed in the controls. CONCLUSION(S) Fertilization and cleavage rates after oocyte freezing are acceptable. Survival is, however, still poor, leading to overall results that make the technique clinically inefficient. There is no increase in the rate of chromosomal abnormalities, indicating that the technique is, nevertheless, safe enough to be further explored and improved.

Five years' experience using oocyte vitrification to preserve fertility for medical and nonmedical indications

OBJECTIVE To evaluate the results of controlled ovarian hyperstimulation (COH) for oocyte vitrification to preserve fertility for medical and nonmedical indications. DESIGN A retrospective, multicenter, observational study performed between March 2007 and June 2012. SETTING University-affiliated infertility clinics. PATIENT(S) Of 560 nononcological patients and 475 oncological patients, we performed 1,080 oocyte vitrification cycles, 725 for nonmedical reasons and 355 in patients affected with cancer. Cycle outcome is presented, including 30 women who returned to use their frozen eggs with, 20 pregnancies obtained, 6 newborns, and 8 ongoing pregnancies. INTERVENTION(S) Controlled ovarian hyperstimulation, oocyte retrieval, warming of oocytes, and ET in those who already came back. MAIN OUTCOME MEASURE(S) Days of stimulation, total dose of gonadotropins, estrogen (E) and P levels, number of oocytes retrieved and vitrified, pregnancy rate (PR). RESULT(S) Comparable results were obtained in both groups of patients, with lower total dose of gonadotropins used and lower serum E(2) levels in patients affected with cancer. Frozen/thawed oocytes performed similarly in both groups. CONCLUSION(S) Patients who vitrify eggs for medical or nonmedical reasons perform similarly, as observed in this large series. This technique offers realistic expectations to both groups of patients to have a child with their own eggs. These data could be used to adequately counsel our patients.

Oocyte vitrification as an efficient option for elective fertility preservation

OBJECTIVE To provide a detailed description of the current oocyte vitrification status as a means of elective fertility preservation (EFP). DESIGN Retrospective observational multicenter study. SETTING Private university-affiliated center. PATIENT(S) A total of 1,468 women who underwent EFP because of age or having associated a medical condition other than cancer (January 2007 to April 2015). INTERVENTION(S) None. MAIN OUTCOME MEASURE(S) Survival and cumulative live birth rate (CLBR) per consumed oocyte. RESULT(S) Mean age was higher with EFP due to age versus having an associated medical reason (37.7 y [95% confidence interval (CI) 36.5-37.9] vs. 35.7 y [95% CI 34.9-36.3]). In total, 137 patients (9.3%) returned to use their oocytes. Overall survival rate was 85.2% (95% CI 83.2-87.2). Live birth rate per patient was higher in women ≤35 years old than ≥36 years old (50% [95% CI 32.7-67.3] vs. 22.9% [95% CI 14.9-30.9]). CLBR was higher and increased faster in younger women. The gain in CLBR was sharp from 5 (15.4%, 95% CI -4.2 to 35.0) to 8 oocytes (40.8%, 95% CI 13.2-68.4), with an 8.4% gain per additional oocyte, in the ≤35-year-old group. The increase was slower with 10-15 oocytes, reaching a plateau CLBR of 85.2%. A milder increase (4.9% gain) was observed in the ≥36-year-old group (from 5.1% [95% CI -0.6 to 10.7] to 19.9% [95% CI 8.7-31.1] when 5-8 oocytes were consumed), reaching the plateau with 11 oocytes (CLBR 35.6%). Forty babies were born. CONCLUSION(S) At least 8-10 metaphase II oocytes are necessary to achieve reasonable success. Numbers should be individualized in women >36 years old. We suggest encouraging women who are motivated exclusively by a desire to postpone childbearing because of age, to come at younger ages to increase success possibilities.

Obstetric and perinatal outcome of babies born from vitrified oocytes

OBJECTIVE To assess outcomes after oocyte vitrification on obstetric and perinatal outcomes compared with those achieved with fresh oocytes. DESIGN Retrospective cohort study. SETTING Private university-affiliated IVF center. PATIENT(S) Children born after use of vitrified oocytes (1,027 from 804 pregnancies) and fresh oocytes (1,224 from 996 pregnancies). Singleton and multiples pregnancies from own and donated ova were included. INTERVENTION(S) Oocyte vitrification by the Cryotop method. MAIN OUTCOME MEASURE(S) Pregnancy, delivery, and neonatal outcomes. RESULT(S) Vitrification had no clinically relevant adverse effects on obstetric and perinatal outcomes after adjusting for potential confounders. No differences were found between the vitrified and fresh oocyte groups in the rate of obstetric problems (including diabetes, pregnancy-induced hypertension, preterm birth, anemia, and cholestasis), gestational age at delivery, birth weight, Apgar scores, birth defects, admission to neonatal intensive care unit (ICU), perinatal mortality, and puerperal problems. Only a greater number of invasive procedures (adjusted odds ratio 2.12; 95% confidence interval 1.41-3.20), and a reduced occurrence of urinary tract infection (adjusted odds ratio 0.51; 95% confidence interval 0.28-0.91), were observed in the vitrified oocytes group. CONCLUSION(S) Although our data, the largest series to date, suggest that oocyte vitrification does not increase adverse obstetric and perinatal outcomes in children conceived with vitrified oocytes, further studies with larger samples are required to reinforce our conclusions.

Accumulation of oocytes: a new strategy for managing low-responder patients

Accumulation of oocytes from several ovarian stimulation cycles is currently possible using novel vitrification technologies. This strategy could increase the inseminated cohort, creating a similar situation to normoresponders. This study included 242 low-responder (LR) patients (594 cycles) whose mature oocytes were accumulated by vitrification and inseminated simultaneously (LR-Accu-Vit) and 482 patients (588 cycles) undergoing IVF/embryo transfer with fresh oocytes in each stimulation cycle (LR-fresh). Drop-out rate in the LR-fresh group was >75%. The embryo-transfer cancellation per patient was significantly lower in the LR-Accu-Vit group (9.1%) than the LR-fresh group (34.0%). Live-birth rate (LBR)/patient was higher in the LR-Accu-Vit group (30.2%) than the LR-fresh group (22.4%). Cumulative LBR/patient was statistically higher in the LR-Accu-Vit group (36.4%) than the LR-fresh group (23.7%) and a similar outcome was observed among patients aged ⩾40years (LR-Accu-Vit 15.8% versus LR-fresh 7.1%). The LR-Accu-Vit group had more cycles with embryo cryopreservation (LR-Accu-Vit 28.9% versus LR-fresh 8.7%). Accumulation of oocytes by vitrification and simultaneous insemination represents a successful alternative for LR patients, yielding comparable success rates to those in normoresponders and avoiding adverse effects of a low response. The accumulation of oocytes from several ovarian stimulation cycles is currently possible with the aid of novel vitrification technologies. This strategy could be useful for low-responder patients, contributing to increase the inseminated cohort and creating a similar situation as in normal responders. According to the results presented herein (higher live-birth rate per patient treated), this strategy represents a successful alternative for low-responder patients, yielding comparable success rates to those in normal responders and avoiding the adverse effects of a low response.

Vitrification versus slow freezing of oocytes: effects on morphologic appearance, meiotic spindle configuration, and DNA damage

To assess possible effects on subcellular organization after cryopreservation, we compared vitrified and slowly frozen oocytes in terms of their post-warm/thaw morphology, meiotic spindle configuration, and DNA integrity. DNA integrity of cryopreserved oocytes was not altered after the procedures, but vitrification was more effective than slow cooling, as shown by higher survival rate and spindle assessment despite a higher misalignment between meiotic spindle and polar body.