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The incidence of multiple pregnancies after in-vitro fertilisation or intracytoplasmic sperm injection (IVF/ICSI) is much higher than after natural conception. It is well known that multiple pregnancies have a less favorable obstetric, neonatal outcome than singletons. It is obvious that a strategy using transfer of only one embryo would result in singletons, but it might also result in a considerable decline in the overall birth rate. Data from randomized controlled trials (RCTs) indicate that single-embryo transfer (SET) results in lower live birth rates per fresh IVF cycle than double-embryo transfer (DET). However, the expectation is that cumulative live birth rates are comparable in the two groups. Twin pregnancies in IVF should be avoided by transferring embryos one at a time, even for frozen cycles. SET is unlikely to be suitable for all women undergoing IVF and outcomes may be sensitive to different laboratory protocols. Other factors affecting the routine use of SET include laboratory techniques, individual preferences and funding issues. An important issue is how to select patients suitable for SET and embryos with a high implantation potential. In the present study, we review data at our clinic in addition to the literature regarding elective single-embryo transfer (eSET) in IVF/ICSI.
Single embryo transfer is advocated as a strategy to reduce the frequency of multiple births after in vitro fertilization. Transfer of a single, blastocyst stage embryo increases the likelihood of pregnancy and delivery as compared with transfer of a single, cleavage-stage embryo in women under 36 years of age undergoing their first or second trial of in vitro fertilization. The reason for the higher success rate with blactocysts might be mainly related to an embryo selection process. In the near future, this approach might be appropriate for women older than 36 years. A potential drawback to the use of blastocysts is failure to transfer any embryos. Additional concerns are the possibilities of an increased risk of monozygotic twins and an altered sex ratio of births.
Elective single embryo transfer (eSET) is becoming increasingly popular in assisted reproductive technology (ART) in order to avoid multiple pregnancies without decreasing the overall pregnancy rate. It is required to strictly select an embryo with the highest implantation potential for the success of eSET. For selection of the best embryo, it is necessary to introduce several scoring systems in combination, such as presence of multinuclearity in blastomeres, evenness of pronuclear size, early cleavage, various oocytoplasmic anomalies, etc. This enables us to rank each embryo in higher developmental competence order. In this review, we analyze the clinical data, retrospectively, in order to inspect the significance of several morphological markers. In addition to the morphological parameters, several non-invasive molecular or genetic markers (such as levels of embryonic soluble HLA-G, platelet-activating factor or total antioxidant capacity in culture media, apoptosis or microarray analysis of follicular cells or cumulus cells, etc.) have been reported as useful indicators of embryo quality. Compared with the morphological parameters, these cellular and molecular predictors of embryo quality may prove to be more precise and objective. By means of analyzing the significance of each indicator, the precision of embryo evaluation will improve as the patient population increases.
Single embryo transfer (SET) originated in Nordic countries and is well accepted in the rest of the world especially in Europe and Japan. Though the clinical situation is very variable, social security systems or reimbursement programs as well as newly introduced legislation or guidelines in these countries have effectively promoted SET in various ways. Recent findings suggest that there is no significant difference in the live-birth ratio between SET and multiple embryo transfer in certain clinical conditions. We should, therefore, encourage the move to SET, subject to informed consent from the patients.
The location of an oocyte spindle can be identified by observing metaphase II (M II) oocytes with a LC-Polscope prior to performing intracytoplasmatic sperm injection (ICSI). Spindle damage caused by ICSI procedure raises concerns as the spindle is not always adjacent to the first polar body (PB1) and is also seen in areas penetrated by ICSI needles. LC-Polscope ICSI guided by spindle location demonstrated a significantly lower abnormal fertilization rate compared to conventional ICSI guided by location of PB1. While spindles visualized by LC-Polscope accounted for 80% of oocytes, differences in fertilization rate, good cleavage rate and blastocyst development rate were observed between visible and invisible spindle groups. These results indicate the possibility of using spindle visibility as an indicator for determining oocyte quality. It also suggests a possible correlation between the retardance of spindle image on LC-Polscope and the blastocyst development rate.
The aim of this study was to determine whether there is a difference in pregnancy outcomes dependent on the kind of hormone replacement treatment in the luteal phase after transfer of frozen-thawed embryos in the natural ovulation cycle. Two hundred and twenty-three cycles were examined in this study. The cycles were divided into three groups. In group A (40 cycles), the luteal phase was supported by human chorionic gonadotropin (hCG). In group B (83 cycles), the luteal phase was supported by hCG and vaginal suppository of progesterone. In group C (100 cycles), the luteal phase was supported by hCG, vaginal progesterone and transdermal estradiol. The pregnancy rate and implantation rate in group C (63.0% and 44.3%) were significantly and 28.0%) and group B (45.8% and 30.3%). In conclusion, administration of vaginal progesterone and transdermal estradiol in addition to hCG in the luteal phase in the natural ovulation cycle is effective for improving pregnancy and implantation rates in patients undergoing transfer of frozen-thawed embryos.