Objective: To evaluate the potential utility of the ratio of the maximal diameter of the bulging foramen ovale flap to the left atrial diameter (FOFD/LAD) for distinguishing false-positive prenatal suspicion of fetal coarctation of the aorta (CoA), and to examine its association with fetal cardiac structural parameters. Materials and Methods: This retrospective study included a selected referral cohort of 44 fetuses with prenatal suspicion of CoA, who were classified postnatally into the false-positive prenatal suspicion group (n = 29) or the true CoA group (n = 15), along with 50 gestational age-matched controls. FOFD, LAD, atrial and ventricular diameters, great-vessel diameters, and aortic isthmus Z-scores were measured. Associations were assessed using Spearman rank correlation, and intergroup differences were evaluated using the Kruskal–Wallis test with Bonferroni-adjusted Mann–Whitney U tests. Results: FOFD/LAD was significantly higher in the false-positive prenatal suspicion group than in the true CoA and control groups (all p < 0.001), whereas no difference was observed between the true CoA and control groups (p = 0.059). In the false-positive and control groups, FOFD/LAD was positively associated with RAD/LAD, RVD/LVD, and PAD/AoD (all p < 0.001). Both suspected CoA groups showed higher right-to-left cardiac structural ratios and aortic isthmus Z-scores than controls (all p < 0.001), but these indices did not differ between false-positive prenatal suspicion and true CoA cases. Conclusions: In a selected cohort of fetuses with prenatal suspicion of CoA, an increased FOFD/LAD may reflect the presence of a redundant foramen ovale flap and may serve as a promising adjunctive parameter for distinguishing RFOF-related CoA mimicry from true CoA. However, given the limited sample size and moderate reproducibility, these findings should be considered exploratory and require validation in larger independent cohorts.
Li et al. (Tue,) studied this question.