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Introduction: The right subclavian artery normally arises as the first vessel from the brachiocephalic trunk. An aberrant right subclavian artery (ARSA) arises directly from the aortic arch and crosses behind the trachea towards the right arm. This variant occurs in approximately 1–2% of the population; however, the frequency increases in individuals with chromosomal abnormalities such as trisomy 21 and 22q11.2 microdeletion. Prenatal identification of ARSA therefore has a role in screening for such conditions. Methods: Databases were searched for studies reporting the prenatal ultrasound evaluation of ARSA and its frequency in normal fetuses and in those with chromosomal abnormalities. Results: A total of 23 studies were evaluated. Feasibility for the ultrasound evaluation of ARSA was 85–95%. The sonographic detection of ARSA is best in the three-vessel trachea view; however, sagittal and coronal imaging of the aortic arch may be useful. ARSA in isolation was not found to be associated with chromosomal abnormalities. The prevalence of ARSA in chromosomally abnormal fetuses was up to 24-fold higher than in normal fetuses, but the majority of chromosomally abnormal fetuses with ARSA had additional abnormal ultrasound findings, particularly cardiac abnormalities. Conclusions: The prenatal detection of ARSA is a clinically useful prenatal marker for chromosomal abnormalities. In isolation, it is unlikely to be associated with pathogenic genetic variants. The ultrasound diagnosis of ARSA should prompt meticulous assessment of associated abnormalities. Invasive diagnostic testing should be offered to patients with non-isolated ARSA or in the presence of non-reassuring screening results or other risk factors. [ABSTRACT FROM AUTHOR]

Background: Nuchal translucency measurement has an established role in first trimester screening. Accurate measurement requires that technical guidelines are followed. Performance can be monitored by auditing the distribution of measurements obtained in a series of cases. Aims: The primary aim is to develop an accessible, theory‐based educational program for individuals whose distribution of measurements at audit falls outside an acceptable range, and assess operator performance following this intervention. Materials and Methods: Operators whose nuchal translucency measurement distributions fall outside a normal range (38–65% above the median) were expected to undergo a teleconference tutorial. Accessible from anywhere in Australia, the one hour tutorials were run by a senior sonographer (to explain technical ultrasound aspects) and the audit program manager (to explain the audit process). Results: In 2011, 83 operators attended the teleconference tutorials. Compared to a random comparison group of operators meeting standard in 2011, teleconference tutorial attendees were significantly more likely to: (i) operate in rural or regional, rather than metropolitan, centres (P = 0.001); (ii) be less experienced (P < 0.0005); and (iii) have lower annual scan numbers (P = 0.0012). Improvement in nuchal translucency measurement quality was seen after one audit cycle and was maintained over subsequent years. The mean percentage of the study cohort reaching standard over the five‐year audit was 77.8% which was not statistically different from the average for the comparison cohort of all other audited operators (79.3%; P = 0.61). Conclusions: Teleconference tutorials are a convenient, accessible and effective way to obtain immediate and sustained improvement in operator performance. [ABSTRACT FROM AUTHOR]

Objectives: To assess the accuracy of non-invasive prenatal testing (NIPT) for sex chromosome aneuploidy (SCA) in routine clinical practice and to review counselling and sonographic issues arising in SCA cases.Methods: Three specialist Australian obstetric ultrasound and prenatal diagnosis practices offering NIPT after 10 weeks' gestation participated in this study. NIPT was reported for chromosomes 21, 18, 13, X, and Y.Results: NIPT screening was performed in 5,267 singleton pregnancies. The odds of being affected given a positive screening result (OAPR) was lowest for SCAs, most notably for monosomy X (20%). Fewer women underwent invasive prenatal testing when counselled regarding a high risk for SCA (65.5%) compared with those who had a high risk for another aneuploidy (85%). The positive screening rate of NIPT including SCA was 2.3%, but 1.2% if only the autosomal trisomies were included in the panel.Conclusion: The addition of SCA testing to NIPT doubles the positive screening rate. The OAPR for SCAs (most notably for monosomy X) is reduced compared with the autosomal trisomies. Clinicians need a more extensive discussion with women prior to the inclusion of the X and Y chromosomes in the NIPT panel, given the complexity in counselling regarding further management and the additional anxiety that these abnormal results may cause. A benefit of sex chromosome analysis is an improvement in antenatal diagnosis of some disorders of sexual development. [ABSTRACT FROM AUTHOR]

Introduction: Biological factors are known to influence the fetal fraction (FF) of cell-free DNA and may also influence the accuracy of non-invasive prenatal testing.Material and Methods: NIPT from 5267 mixed risk women across three specialist clinics in Australia were analyzed. Multivariable regression analysis was used to determine whether maternal characteristics, ultrasound, and placental biomarkers affect FF and test accuracy.Results: FF ranged from 4% to 37% (mean 11.6%). Body mass index (BMI), gestation, and placental biomarkers were found to be significant factors associated with FF. For each unit increase in BMI, the logarithmically transformed FF, (lnFF), mean value decreased by 0.027. Each week increases in gestation, lnFF increased by 0.023. Each unit increase in free BhCG, PAPPA, and PlGF, the lnFF increased by 0.065, 0.050, and 0.17, respectively. There was no significant association between FF with either maternal age or nuchal translucency. The false-positive cases and one false-negative case did not have lower FF than the true-positive cases.Discussion: The fetal fraction in maternal plasma cfDNA increased with gestational age, serum pregnancy-associated plasma protein A (PAPP-A), β-hCG, and PlGF and decreased with increasing maternal BMI. There was no significant correlation between low FF and test accuracy, when FF was above 4%. [ABSTRACT FROM AUTHOR]