“Triangle Method” for Evaluating the Morphological Characteristics of the Aortic Arch in Healthy Mid‐to‐Late Pregnancy Fetuses

OBJECTIVES: This study aimed to apply the 2-dimensional grayscale ultrasound "triangle method" to evaluate the morphology of the aortic arch in healthy mid-to-late pregnancy fetuses. METHODS: weeks of gestation were assessed. Using the long-axis view of the aortic arch, the "triangle method" was employed to measure the aortic arch length (sum of the 2 sides of a triangle), width, height, and angle. The aortic arch tortuosity (length/width) and height-to-width ratio were calculated. Healthy reference values for these morphological parameters were established, and their relationship to gestational age (GA) and cardiac valve annuli was explored. RESULTS: The length, width, and height of the aortic arch in healthy mid-to-late pregnancy fetuses increased significantly with GA (P < .05). Instead, no significant correlation was observed between GA or cardiac valve annuli and the aortic arch angle, tortuosity, or height-to-width ratio (P > .05), whose corresponding reference values were 69.2 ± 6.1°, 1.7 ± 0.1, and 0.7 ± 0.1, respectively. CONCLUSIONS: The aortic arch angle, tortuosity, and height-to-width ratio in healthy mid-to-late pregnancy fetuses remain relatively stable during development.