2089 correspondence reflects improvements in patient care rather than case selection.In response to de Miguel-Yanes et al.: we did not evaluate the subgroup with diabetes in our initial analysis. However, in contrast with de MiguelYanes et al., after stratifying our sample according to the presence of diabetes we observed higher mortality for the subgroup of patients with diabetes, and this difference persisted over time.We agree with Hussain and Al-Omran that surgical volume is an important predictor of outcomes for abdominal aortic aneurysm repair. 1 In our previous work, we found that the relationship between hospital volume and outcomes was quite different for endovascular repair versus open repair and that experience with one type of repair did not carry over to improved outcomes in the other type of repair. We therefore did not conduct propensityscore matching for procedure volume in our analysis, since doing so would have been helpful only for comparisons of the same procedure, not for comparisons between different procedures.

No specific funding was obtained for this study. None of the authors have any competing interests to declare.

No abstract

The data obtained demonstrate that array-CGH can detect chromosome imbalances in embryos, also providing the added benefit of simultaneous aneuploidy screening of all 24 chromosomes. Array-CGH has the potential to overcome several inherent limitations of FISH-based tests, providing improvements in terms of test performance, automation, sensitivity and reliability.

In 2005, the European Society for Human Reproduction and Embryology (ESHRE) PGD Consortium published a set of Guidelines for Best Practice PGD to give information, support and guidance to potential, existing and fledgling PGD programmes. The subsequent years have seen the introduction of a number of new technologies as well as the evolution of current techniques. Additionally, in light of recent advice from ESHRE on how practice guidelines should be written and formulated, the Consortium believed it was timely to revise and update the PGD guidelines. Rather than one document that covers all of PGD, as in the original publication, these guidelines are separated into four new documents that apply to different aspects of a PGD programme, i.e. Organization of a PGD centre, fluorescence in situ hybridization-based testing, Amplification-based testing and Polar Body and Embryo Biopsy for PGD/preimplantation genetic screening. Here, we have updated the sections that pertain to amplification-based PGD. Topics covered in this guideline include inclusion/exclusion criteria for amplification-based PGD testing, preclinical validation of tests, amplification-based testing methods, tubing of cells for analysis, set-up of local IVF centre and Transport PGD centres, quality control/quality assurance and diagnostic confirmation of untransferred embryos.

Not applicable.

These findings provide critical insights into the mechanisms causing errors during female meiosis and the preimplantation embryo development period to improve the design and treatment outcome of PGS.

Objective To assess the feasibility of offering array-based comparative genomic hybridization testing for prenatal diagnosis as a first-line test, a prospective study was performed, comparing the results achieved from array comparative genomic hybridization (aCGH) with those obtained from conventional karyotype.Method Women undergoing amniocentesis or chorionic villus sampling were offered aCGH analysis. A total of 1037 prenatal samples were processed in parallel using both aCGH and G-banding for standard karyotyping. Specimen types included amniotic fluid (89.0%), chorionic villus sampling (9.5%) and cultured amniocytes (1.5%).Results Chromosomal abnormalities were identified in 34 (3.3%) samples; in 9 out of 34 cases (26.5%) aCGH detected pathogenic copy number variations that would not have been found if only a standard karyotype had been performed. aCGH was also able to detect chromosomal mosaicism at as low as a 10% level. There was complete concordance between the conventional karyotyping and aCGH results, except for 2 cases that were only correctly diagnosed by aCGH.Conclusions This study demonstrates that aCGH represents an improved diagnostic tool for prenatal detection of chromosomal abnormalities. Although larger studies are needed, our results provide further evidence on the feasibility of introducing aCGH as a first-line diagnostic test in routine prenatal diagnosis practice.