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J Ultrasound Med. 2018 Aug;37(8):1869-1880. doi: 10.1002/jum.14533. Epub 2017 Dec 27.

"Y Sign" at the Level of the 3-Vessel and Trachea View: An Effective Fetal Marker of Aortic Dextroposition Anomalies in the First Trimester.

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Center for Prenatal Diagnostics, Opole, Poland.
Dobreusg Ultrasound Group Practice, Krakow, Poland.
Departments of Gynecology and Obstetrics, Jagiellonian University, Krakow, Poland.
Polish Mother's Memorial Hospital Research Institute, Lodz, Poland.
Profemi Private Practice, Krotoszyn, Poland.
Departments of Pediatric Cardiology, Jagiellonian University, Krakow, Poland.
Department of Gynecology and Obstetrics, Frederic Chopin Clinical District Hospital No. 1, Rzeszow, Poland.



The "Y sign" at the level of the 3-vessel and trachea view corresponds to thinning of main pulmonary artery and arterial duct and a dilated transverse aortic arch. The purpose of this study was to evaluate the Y sign for the diagnosis of aortic dextroposition anomalies at the time of the first-trimester scan and to assess the screening performance of only the Y sign, only abnormal left axis deviation (axis sign), and their combination for the diagnosis of aortic dextroposition anomalies.


A prospective evaluation of 6025 pregnant women undergoing first-trimester ultrasonography was conducted. The cardiac axis was measured in all examined patients and considered abnormal (positive axis sign) at greater than 57 °. The frequency of the Y sign and the axis sign was assessed for this population, and their screening performance for the diagnosis of aortic dextroposition anomalies was calculated.


A total of 5775 patients fulfilled the inclusion criteria. Aortic dextroposition anomalies were diagnosed in 17 cases (tetralogy of Fallot in 8 and Fallot-like double-outlet right ventricle in 9). The Y sign was found in 18 of 5775 (0.3%) fetuses examined, of which 7 of 18 were confirmed with tetralogy of Fallot, 9 of 18 with a Fallot-like double-outlet right ventricle, and 2 of 18 with pulmonary stenosis. A positive axis sign of greater than 57 ° was found in 20 fetuses, including 4 with normal heart anatomy. The sensitivity values of the Y sign, the axis sign, and their combination were 94%, 76%, and 94%, respectively.


Visualization of the Y sign should increase the suspicion of aortic dextroposition anomalies in the late first trimester. The screening performance of the Y sign alone and in combination with an abnormal cardiac axis was high and may aid in the early diagnosis of aortic dextroposition anomalies in the fetus.


double-outlet right ventricle; early fetal echocardiography; first-trimester ultrasonography; obstetrics; prenatal ultrasonography; tetralogy of Fallot

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