Measurement of fetal automated fractional shortening using two-dimensional tracking in multiple centers

To establish a normal reference range for automated fractional shortening (Auto FS) in normal singleton fetuses measured at multiple centers.

This study was conducted from May 2017 to March 2019. It was undertaken on normal singleton fetuses. First, a four-chamber view of the fetal heart was recorded in the B-mode. Then, the region of interest was set on the edge of the ventricular septum and on the edge of the ventricular muscle at a point one-third away from the atrioventricular valve and toward the cardiac apex. Tracking was automatically performed. Values measured in the right ventricle were defined as R-Auto FS, and in the left ventricle as L-Auto FS. Furthermore, combined-Auto FS was defined as the measurement across both ventricles.

A total of 442 normal fetuses were assessed. R-Auto FS decreased significantly with gestational age, and L-Auto FS showed a similar tendency (Spearman's correlation analysis: r_s =  - 0.415 and r_s =  - 0.252, respectively). Combined-Auto FS showed a similar decline as the gestational age increased (r_s =  - 0.451).

In this study, we succeeded in defining a reference Auto FS value not only at one institution but also multiple centers. This study suggests that Auto FS can be used clinically and effectively.