3-VESSEL VIEW OF THE FETAL UPPER MEDIASTINUM - AN EASY MEANS OF DETECTING ABNORMALITIES OF THE VENTRICULAR OUTFLOW TRACTS AND GREAT-ARTERIES DURING OBSTETRIC SCREENING

The three-vessel view is a transverse view of the fetal upper mediasti num is as simple to obtain as the four-chamber view. It demonstrates t he main pulmonary artery, ascending aorta and superior vena cava in cr oss- or oblique sections. The purposes of this study were to describe the normal anatomy of the three-vessel view and to analyze what anatom ical changes would occur in this view when there are lesions of the ve ntricular outflow tracts and/or great arteries. Sonograms of 29 fetuse s with lesions involving the ventricular outflow tracts and/or great a rteries were reviewed. Three-vessel views were evaluated in terms of v essel size, number, arrangement and alignment. Twenty-eight of 29 fetu ses showed an abnormal three-vessel view that included abnormal vessel size (n = 12), abnormal alignment (n = 8), abnormal arrangement (n = 7) and abnormal vessel number (n = 3). The vessel size was abnormal in obstructive lesions of the right (n = 4) or the left (n = 8) side of the heart. An abnormal alignment was seen in tetralogy of Fallot (n = 6) and double-outlet right ventricle (n = 2) that showed anterior disp lacement of the aorta. An abnormal arrangement was seen in complete (n = 4) and corrected (n = 1) transpositions, double-outlet right ventri cle (n = 1) and pulmonary atresia with ventricular septal defect (n = 1). Only. two vessels were seen in truncus arteriosus (n = 1). Four ve ssels were seen in persist ent left superior vena cava (n = 2). A fetu s with pulmonary atresia and intact ventricular septum showed a normal three-vessel view. In conclusion, most of the lesions involving the v entricular outflow tracts and/or great arteries showed an abnormal thr ee-vessel view.