The Upturned Superior Mesenteric Artery Sign for First‐Trimester Detection of Congenital Diaphragmatic Hernia and Omphalocele

Abstract

The aim of this study was to follow the course of the superior mesenteric artery (SMA) in first-trimester fetuses to predict the location of the small bowel. Its abnormal course aids in early detection of congenital diaphragmatic hernia (CDH) and assessment of the contents of omphalocele. The SMA can be easily identified in a sagittal section of the fetus by using color Doppler sonography at the 11- to 14-week scan, and normally, it has a downward course caudally to supply the intestines. The course of the SMA points to the location of the bowel. We report a series of 7 cases detected in first trimester with an abnormal course of the SMA, 3 of which had CDH and 4 of which had omphalocele. In CDH, the intestines herniate into the thoracic cavity; hence, the SMA tends to have an upward course toward the thorax. In 4 cases of omphalocele, the SMA follows the exteriorized bowel into the base of the umbilical cord. Second-trimester sonography for detection of congenital malformations is a standardized protocol, but a careful anatomic survey at the 11- to 14-week scan is often rewarding. When there is a suspicion of an intrathoracic mass or a mediastinal shift, the upturned course of SMA serves as a valuable sign in confirmation of CDH. Chromosomal abnormalities are often reported in cases of omphalocele containing small bowel only, and the upward course of the SMA toward the base of the cord helps in its early prenatal diagnosis, which facilitates early genetic assessment in these fetuses.