Aberrant right subclavian artery as soft marker in the diagnosis of trisomy 21 during the first trimester of pregnancy.

PURPOSE: Aberrant right subclavian artery is an anatomical variation with a prevalence of around 0.5-1.5% of the general population, being more frequently found among people with chromosomopathies, especially, trisomy 21. Despite being an anatomical finding, and thus, constant through the whole pregnancy, its value in the diagnosis of aneuploidies during the first trimester of pregnancy has been little studied. The aim of this study is to evaluate the reliability of the first-trimester ultrasound in the diagnosis of ARSA and its utility in the early diagnosis of aneuploidies. METHODS: This was a descriptive, observational, cross-sectional study that included all fetuses with sonographic diagnosis of ARSA between 2011 and 2018. RESULTS: There were 257 cases of ARSA diagnosed. The first-trimester ultrasound showed the following results in the detection of ARSA: sensitivity of 68% (CI 95% 60.8%-74.5%), specificity of 99.9% (CI 95% 99.9%-100%), positive predictive value of 93.7% (CI 95% 88.1%-96.8%), and negative predictive value of 99.6% (CI 95% 99.5%-99.7%). Due to the presence of ARSA, two cases of trisomy 21, that would have been missed in the first trimester, were diagnosed, using ARSA as a soft marker and modifying the risk obtained by the combined screening as part of the genetic sonogram of the first trimester. CONCLUSIONS: ARSA visualization during the first-trimester ultrasound is trustworthy and it can improve the detection of trisomy 21 in some cases of aneuploidy missed during the combined screening of the first trimester.

Is it useful to evaluate the presence of aberrant right subclavian artery in prenatal diagnosis ultrasounds?

AIM: Analyze if the evaluation of aberrant right subclavian artery in the prenatal echography has improved the detection of chromosomal, genetic and/or morphological abnormalities in our population. METHODS: Descriptive, observational, cross-sectional study of the cases of aberrant right subclavian artery diagnosed in our Prenatal Diagnosis Unit between January of 2011 and December of 2018. RESULTS: Two hundred and fifty-seven cases of aberrant right subclavian artery were diagnosed and among them, 179 were considered isolated cases and thus were confirmed after birth. The detection of aberrant right subclavian artery did not improve itself neither the diagnosis of trisomy 21 in the second trimester of pregnancy nor other chromosomal or genetic abnormalities, including the not isolated cases. There were two cases of trisomy 21 diagnosed in the second trimester that presented major sonographic disorders and an inadequate examination during the first trimester. When aberrant right subclavian artery was associated with soft markers of aneuploidy in the second trimester, any case was a trisomy 21. Aberrant right subclavian artery seems to be associated with some minor and major heart defects, especially ventriculoseptal defect and aneurismatic ductus, and in some cases, also with clubfeet. CONCLUSION: When an adequate screening of aneuploidies and a thorough ultrasound have been performed during the first trimester, aberrant right subclavian artery hardly helps to perform other diagnosis in the second trimester.