BackgroundEmbryos produced by in vitro fertilization (IVF) have a high level of aneuploidy, which is believed to be a major factor affecting the success of human assisted reproduction treatment. The aneuploidy rate of cleavage stage embryos based on 1–2 biopsied blastomeres has been well-reported, however, the true aneuploidy rate of whole embryos remain unclear because of embryo mosaicism. To study the prevalence of mosaicism in top quality IVF embryos, surplus embryos donated from young patients (aged 28–32) in the assisted reproduction program at Queen Mary Hospital, Hong Kong were used.MethodsThirty-six good quality day 2 embryos were thawed. Out of the 135 blastomeres in these embryos, 121 (89.6%) survived thawing. Twelve of these embryos without lysed blastomeres and which cleaved to at least seven cells after a 24-h culture were dissembled into individual blastomeres, which were analysed by array comparative genomic hybridization and microsatellite marker analysis by fluorescent PCR.ResultsOut of 12 day-3 embryos, 2 (16.7%) were normal, 3 (25%) were diploid/aneuploidy with <38% abnormality, 4 (33.3%) were diploid/aneuploidy mosaic with > =38% abnormality, and three (25%) were mosaic aneuploids. Conclusive chromosomal data were obtained from a high percentage of blastomeres (92.8%, 90/97). Microsatellite marker analysis performed on blastomeres in aneuploid embryos enabled us to reconstruct the chromosomal status of the blastomeres in each cleavage division. The results showed the occurrence of meiotic errors in 3 (25%) of the studied embryos. There were 16 mitotic errors (18.8%, 16/85) in the 85 mitotic divisions undertaken by the studied embryos. The observed mitotic errors were mainly contributed by endoreduplication (31.3%, 5/16), non-disjunction (25%, 4/16) and anaphase lagging (25%, 4/16). Chromosome breakages occurred in 6 divisions (7.1%, 6/85).ConclusionsMosaicism occurs in a high percentage of good-quality cleavage stage embryos and mitotic errors contribute significantly to the abnormality.Electronic supplementary materialThe online version of this article (doi:10.1186/1477-7827-12-105) contains supplementary material, which is available to authorized users.

Second trimester abortion remains a common procedure worldwide. Dilatation and evacuation (D&E) is the surgical method of choice, if the surgical expertise and facilities are available. Adequate cervical dilatation preoperatively is a prerequisite for a safe D&E. Medical abortion using misoprostol together with mifepristone is the medical method of choice. The recommended regimen is 200mg mifepristone followed by 800 microg of vaginal misoprostol 36-48 h later. Subsequent doses of 400 microg of misoprostol can be given orally every 3h up to a maximum of four more doses. Proper preoperative assessment would not only help to provide safe abortion treatment, but it also guides the choice of method. If the expertise and facilities of both methods are available, both methods should be discussed and offered to the patient so that the patient can make an informed choice.

Objective: To report the outcomes of more than 100 cycles of preimplantation genetic diagnosis for monogenetic diseases. Interventions: In-vitro fertilisation, intracytoplasmic sperm injection, embryo biopsy, and preimplantation genetic diagnosis. Main outcome measures:Ongoing pregnancy rate and implantation rate. Results:Overall, 124 cycles of preimplantation genetic diagnosis were initiated in 76 patients, 101 cycles proceeded to preimplantation genetic diagnosis, and 92 cycles had embryo transfer. The ongoing pregnancy rate was 28.2% per initiated cycle and 38.0% per embryo transfer, giving an implantation rate of 35.2%. There were 16 frozenthawed embryo transfer cycles in which, following Experience of more than 100 preimplantation genetic diagnosis cycles for monogenetic diseases using whole genome amplification and linkage analysis in a single centre

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