Right-sided aortic arch in the age of microarray.

OBJECTIVE: For fetuses with a diagnosis of right aortic arch and normal cardiac anatomy, we aimed to establish the frequency of chromosomal anomaly diagnosed with single nucleotide polymorphism microarray analysis, particularly focusing on microduplications or microdeletions which would have gone undetected by conventional karyotyping and six-probe fish (13,18,21, X,Y, TUPLE). METHOD: Retrospective study of fetal ultrasounds between 2011 and 2016 in an Australian tertiary referral centre. Outcomes of interest were survival and postnatal surgery for vascular ring. RESULTS: Thirty patients were identified; 24 were apparently isolated. Chromosomal anomalies were identified in eight fetuses (32%) of 25 who had chromosomal testing. The rate in isolated cases was 11% and 56% in non-isolated cases. The 22q11.2 deletion was identified in three fetuses (12%). Microarray identified copy number variants of potential clinical significance in four additional fetuses (16%). Long continuous stretches of homozygosity were identified in one fetus with cerebellar hypoplasia potentially identifying the loci for recessive mutations. Surgery for vascular ring was performed on seven infants (25%) CONCLUSION: Microarray detected clinically significant chromosomal anomalies in fetuses with right aortic arch that would not be detected with conventional karyotyping. Prenatal counselling should include the chance of postnatal surgery and the importance of long-term follow-up. © 2017 John Wiley & Sons, Ltd.

Noninvasive prenatal testing in routine clinical practice--an audit of NIPT and combined first-trimester screening in an unselected Australian population.

BACKGROUND: There are limited data regarding noninvasive prenatal testing (NIPT) in low-risk populations, and the ideal aneuploidy screening model for a pregnant population has yet to be established. AIMS: To assess the implementation of NIPT into clinical practice utilising both first- and second-line screening models. MATERIALS AND METHODS: Three private practices specialising in obstetric ultrasound and prenatal diagnosis in Australia offered NIPT as a first-line test, ideally followed by combined first-trimester screening (cFTS), or as a second-line test following cFTS, particularly in those with a calculated risk between 1:50 and 1:1000. RESULTS: NIPT screening was performed in 5267 women and as a first-line screening method in 3359 (63.8%). Trisomies 21 and 13 detection was 100% and 88% for trisomy 18. Of cases with known karyotypes, the positive predictive value (PPV) of the test was highest for trisomy 21 (97.7%) and lowest for monosomy X (25%). Ultrasound detection of fetal structural abnormality resulted in the detection of five additional chromosome abnormalities, two of which had high-risk cFTS results. For all chromosomal abnormalities, NIPT alone detected 93.4%, a contingent model detected 81.8% (P = 0.097), and cFTS alone detected 65.9% (P < 0.005). CONCLUSIONS: NIPT achieved 100% T21 detection and had a higher DR of all aneuploidy when used as a first-line test. Given the false-positive rate for all aneuploidies, NIPT is an advanced screening test, rather than a diagnostic test. The benefit of additional cFTS was the detection of fetal structural abnormalities and some unusual chromosomal abnormalities.

Auditing ultrasound assessment of fetal nuchal translucency thickness: a review of Australian National Data 2002-2008.

BACKGROUND: Nuchal translucency (NT) measurement is the ultrasound component of first trimester combined screening for Down syndrome. In 2002, a NT ultrasound education and monitoring program was established in Australia. Between 2002 and 2008, a total of 728,502 NT scans were audited through this process. OVERALL AIM: To audit the availability and performance of certified operators measuring NT following implementation of the Australian education and monitoring program in 2002. METHODS: Retrospective review of the central database that is used to monitor performance of individuals and practices performing NT scans in both public and private practice settings throughout Australia between 2002 and 2008. The performance of operators was assessed by a widely used international standard - that 40-60% of NT measurements should be above the median value for gestational age. RESULTS: The number of certified operators has increased (from 184 in 2002 to 477 in 2008). There is wide variation between states in the number of operators per birth. The percentage of certified operators with a measurement distribution meeting the international standard has increased from 40% in 2002 to 55% in 2008. Greatest improvement has been seen in operators performing 30-199 scans per year. There has been no overall improvement in performance over the last three audit cycles. CONCLUSIONS: The number of operators certified to perform the NT scan has increased since 2002, although availability in some states remains low. An initial improvement in performance of operators appears to have reached a plateau. It is time to become more proactive in engaging operators in the audit cycle.