Marisa López-Teijón

Processing of semen can result in increased sperm DNA fragmentation

Processing of semen for assisted reproductive technologies (ART) entails a number of procedures that include semen liquefaction, removal of seminal plasma by centrifugation, incubation, and cryopreservation. The results of this study indicate that incubation of semen at room temperature and semen cryopreservation can result in increased levels of sperm DNA fragmentation.

Association between endometrial thickness in oocyte donation cycles and pregnancy success rates

Endometrial receptivity is a primary concern for embryo implantation success in fertility treatments. The present study was a retrospective analysis of 4070 cycles with donor oocytes and hormone-replacement therapy. Endometrial thickness was assessed once with transvaginal ultrasound. Patients were allowed to continue when endometrial thickness was ?5mm and had triple line morphology. Pregnancy rates, the number of gestational sacs and miscarriage rates were analysed in relation to endometrium status. Regression models were used to analyse associations, taking the day of embryo transfer into account. All patient parameters were homogeneous. Mean endometrial thickness was 7.24±1.66mm, the mean number of embryos transferred was 2.04±0.43, the pregnancy rate was 48.06% and sacs were present in 42.3% of cycles. There were no significant differences in pregnancy rates, number of gestational sacs and miscarriage rates for different endometrial thickness measurements. The present study is, to our knowledge, the largest study evaluating the role of endometrial thickness in oocyte donation cycles. Endometrial thickness >5mm is a reasonable parameter for determining treatment success, and once it is observed in a single ultrasonographic evaluation there is no need for subsequent monitoring and embryo transfer can be scheduled over the following 1-16 days, because the results are not compromised. This may lead to a significant reduction in time and cost in fertility clinics.

A 24-chromosome FISH technique in preimplantation genetic diagnosis: validation of the method.

Abstract Embryo screening for aneuploidy (AS) is part of preimplantation genetic diagnostics (PGD) and is aimed at improving the efficiency of assisted reproduction. Currently, several technologies, including the well-established fluorescence in situ hybridization (FISH) technique, cover the screening of all chromosomes in a single cell. This study evaluates a novel 24-chromosome FISH technique protocol (FISH-24). A total of 337 embryos were analyzed using the traditional 9-chromosome FISH technique (FISH-9) while 251 embryos were evaluated using the new FISH-24 technique. Embryos deemed nontransferable on Day 3 were cultured in vitro to Day 5 of development, then fixed and reanalyzed according to the technique allocated to each treatment cycle (107 embryos analyzed by FISH-9 and 111 by FISH-24). The global error rate (discrepancy between Day 3 and Day 5 results for a single embryo) was 2.8% after FISH-9 and 3.6% after FISH-24, with a p value of 0.95. Thus, we have established and validated a 24-chromosome FISH-based single cell aneuploidy screening technique, showing that the error rate obtained for FISH-24 is independent of the number of chromosomes analyzed and equivalent to the error rate observed for FISH-9, as a useful tool for chromosome segregation studies and clinical use.

A study of meiotic segregation in a fertile human population following ovarian stimulation with recombinant FSH-LH

ObjectiveThe aim of the study is to investigate the meiotic segregation in fresh eggs from anonymous egg donors and to analyze the baseline levels of aneuploidy in this population.ResultsThe study includes the largest series of donor eggs so far studied: 203 eggs from donors aged between 20 and 31 years. No diagnosis was obtained in 10.8 % of cases (22/ 203). The biopsy of the first and second polar bodies was completed in a sequential manner on day 0 and day 1 of embryo development. Chromosomes 13, 16, 18, 21 and 22 are analyzed by means of the FISH test. The diagnosable fertilized eggs gave an aneuploidy rate of 19.1 % (31/162), with 83.8 % (26/31) of the errors produced during meiosis I, 12.9 % (4/31) produced during meiosis II, and 3.2 % (1/31) produced during both meiosis I and II. The premature division of sister chromatids is the main source of meiotic error during Meiosis I, resulting in the creation of oocyte aneuploidy.ConclusionsFISH analysis of the first and second polar body in donor oocytes gave an aneuploidy rate of 19.1 %. This study shows the majority of errors occur during Meiosis I.