A. Fiorentino

Preimplantation genetic diagnosis increases the implantation rate in human in vitro fertilization by avoiding the transfer of chromosomally abnormal embryos

OBJECTIVE To verify the percentage of chromosomally abnormal preimplantation embryos in patients with a poor prognosis and possibly to increase the chance of implantation by selecting chromosomally normal embryos. DESIGN A prospective, randomized, controlled study. SETTING In vitro fertilization program at the Reproductive Medicine Unit of the Società Italiana Studi Medicina della Riproduzione, Bologna, Italy. PATIENT(S) In a total of 28 stimulated cycles, the maternal age was > or = 38 years and/or the patient had > or = 3 previous IVF failures, factors that indicated a poor prognosis. After consent, 11 patients underwent preimplantation genetic diagnosis for aneuploidy, whereas 17 controls underwent assisted zona hatching. INTERVENTION(S) Simultaneous analysis of chromosomes X, Y, 13, 18, and 21 in a blastomere biopsied from day-3 embryos. Chromosomal analysis was performed with fluorescence in situ hybridization. Assisted zona hatching was performed on day-3 embryos from the control-group patients. MAIN OUTCOME MEASURE(S) Embryo morphology, results of fluorescence in situ hybridization, clinical pregnancies, and implantation. RESULT(S) In the study group, a total of 61 embryos were analyzed by fluorescence in situ hybridization, and 55% were chromosomally abnormal. Embryo transfer with at least one normal embryo was performed in 10 cycles. Four clinical pregnancies resulted, with a 28.0% implantation rate. In the control group, 41 embryos were transferred in 17 cycles after the assisted zona hatching procedure, yielding four clinical pregnancies and an 11.9% implantation rate. CONCLUSION(S) Infertile patients classified as having a poor prognosis have a high percentage of chromosomally abnormal embryos. The advantage of selecting and transferring embryos with normal fluorescence in situ hybridization results has an immediate impact on implantation.

Energy substrates, mitochondrial membrane potential and human preimplantation embryo division

Carbohydrate additives to modern embryo culture media are based on three basic energy sources, glucose, pyruvate and lactate. Although the use of these substrates is almost universal, debate continues as to the roles of the individual components in the human. This is mainly due to the lack of human embryos for research and the reliance on animal model systems. In the present work, the human embryo was used to study the role of the above simple substrates in the maintenance of the mitochondrial membrane potential and cell division. The mitochondrial membrane potential was measured with fluorescence techniques. Cell division was scored as the number of blastomeres on day 3. Both the mitochondrial membrane potential and cell division were dramatically lost in the absence of energy sources. The mitochondrial membrane potential and cell division were normal in media containing all three energy sources, or in pyruvate-containing media. Both glucose and lactate individually proved poor energy sources for the maintenance of the mitochondrial membrane potential. However, cell division continued in the presence of glucose, suggesting that some energy production can continue. These data suggest that pyruvate is an absolute requirement for mitochondrial respiration and cell cleavage during human preimplantation development. The role of lactate is as yet unclear.

Zygote Versus Embryo Transfer: A Prospective Randomized Multicenter Trial

AbstractPurpose: To determine the efficiency of transferring human zygotes as opposed to human day 2 or 3 embryos. Methods: A prospective, randomized, Multicenter trial. Patients were randomized into zygote or embryo transfer. Patients were prepared for oocyte retrieval using standardized protocols. Oocyte retrieval was performed under general anesthesia. Oocytes and spermatozoa were treated using standard laboratory techniques. All protocols were coordinated by the coordinating center. Results: A total of 386 patients were included in the trial. Pregnancy rates were 36.5% after zygote transfer and 42% after embryo transfer. Implantation rates were equivalent (17%) in both groups. Conclusions: No general difference was observed for zygote or embryo transfer. The results suggest that zygote transfer is a valid alternative to embryo transfer.

Sperm: Oocyte ratios in an in vitro fertilization (IVF) program

PurposeDuring the past few years, many oocyte insemination techniques, including microinjection, have evolved in the treatment of male-factor infertility. This preliminary study was designed to evaluate whether microdroplet insemination could be considered a reliable technique, especially for semen samples with male-factor defects. The first objective was to assess fertilization rates obtained by inseminating sibling oocytes using both the conventional IVF and the microdroplet method (Group 1). The second objective was to evaluate subsequent embryo development and pregnancy rates resulting from microdroplet insemination, in addition to formulating adequate sperm∶ oocyte ratios for various semen categories (Group 2). Four semen categories were studied including fresh normal sperm, frozen/thawed normal sperm, and male-factor sperm with one defect and two or three defects.ResultsGroup 1 consisted of 54 couples; no statistical significance was found in the fertilization rates between test tube and microdroplet insemination in all four semen categories. Based on these results, patients from Group 2 (48 couples) had their oocytes inseminated only in microdroplets with sperm:oocyte ratios ranging from 2000 to 10,000 motile sperm:1 oocyte. The average fertilization rate for male-factor sperm was 55%, with a 91% cleavage rate.ConclusionHigher fertilization rates were observed in the lowest range of sperm∶oocyte ratios (2000–4000∶1) for male-factor sperm with one defect and in the highest range (8000–10,000∶1) for male-factor sperm with two or three defects. Polyspermy occurred in only 0.4% of the oocytes inseminated. Microdroplet insemination is an alternative treatment for moderate to moderately severe male-factor infertility, establishing a bridge between conventional IVF and microinjection. With adequate sperm∶oocyte ratios, this technique allows the natural selection process of fertilization in vitro to take place, without the high incidence of polyspermy or mechanical damage frequently observed in assisted fertilization techniques.