[Observation of the superior mesenteric artery by ultrasonography: for prediction of the superior mesenteric artery syndrome].

Superior mesenteric artery (SMA) syndrome is a major complication after scoliosis surgery. The author reports an ultrasonic observation of the SMA in normal and scoliotic individuals. There are three patterns of the SMA anatomy: Type I in which the SMA runs very close and parallel to the aorta, Type II in which the SMA branches off the aorta at a certain angle and Type III in which the SMA runs parallel to the aorta. Dynamic observation revealed that passage of food displaces the SMA anteriorly and to the left and that turning to the left from a supine position displaces the SMA from just anterior to the left of the aorta in normal individuals and from the right to the left side of the aorta in scoliosis cases. AMA itself has no significance in the occurrence of SMA syndrome because the SMA moves rather freely with the passage of food or position change. When this natural movement of the SMA is disturbed, one should carefully look for the possibility of SMA syndrome.