Significance of Fetal Aberrant Right Subclavian Artery and Comparison with Other Second Trimester Markers for Down Syndrome Screening

Abstract

The chief objectives of our study were to assess the incidence and significance of fetal aberrant right subclavian artery (ARSA) in a nonreferral cohort of south Indian antenatal woman, and to compare it with other second trimester markers of Down syndrome. This was a prospective study conducted at Edappal hospital, India. After satisfying inclusion and exclusion criteria, 2000 consecutive antenatal women, seeking prenatal care and planning delivery at the same center, were recruited in a consecutive fashion. ARSA was identified as a retrotracheal arterial vessel in the axial three vessel trachea view, coursing towards right axilla. During February 2015 to January 2016, nine cases of ARSA were identified amongst 2000 antenatal women, yielding an incidence of 0.45 % (95 % CI 0.2–0.9 %). Of these, eight cases (8/9, 89 %) were isolated with normal karyotype, and negative for 22q11 microdeletion. Down syndrome was prenatally diagnosed in four cases (4/2000, 0.2 %), with ARSA detected in one case [sensitivity—25 %, specificity—99.6 %, positive likelihood ratio (+LR)—62.5 %, negative likelihood ratio (-LR)—0.75 %; Odds ratio 82.8 %, 95 % CI 7.8–883]. Of the significant second trimester minor markers, an absent nasal bone was the most common (13/2000, 0.65 %), followed by ARSA. All the isolated cases had normal neonatal outcomes. ARSA is relatively common second trimester aneuploidy marker, associated with high global +LR but nil isolated +LR. Indication for fetal karyotype in isolated cases seems to be weak.

Keywords

Aberrant right subclavian artery - Down syndrome - Aneuploidy markers - Subclavian view - Aortic arch - Three vessel trachea view

Publication History

Received: 23 September 2016

Accepted: 11 October 2016

Article published online:
08 May 2023