Comparisons of foramen ovale flap in the fetuses with true and false positive diagnosis of coarctation of the aorta.

Abstract

Accurate diagnosis of coaractation of aorta (CoA) remains challenging because of its relatively low sensitivity and specificity. It is difficult to distinguish true CoA from a normal physiological right-sided dominance or ventricular discrepancy caused by intracardiac minor anomalies. Redundant foramen ovale flap (RFOF) may cause ventricular disproportion. All fetuses suspected with CoA on routine screening ultrasound were retrospectively reviewed and allotted into two groups: postnatally confirmed CoA (true positive group) and prenatally suspected CoA but without CoA postnatally (false positive group). Sixty-nine normal fetuses were included as a normal group (normal group). The diameters of FOF and left atrium (LA) were measured in the four-chamber view and FOF/LA ratio ≥0.65 was considered as RFOF. Cardiac parameters between groups were compared. Fifty-seven fetuses undergoing echocardiography for suspicion of CoA were enrolled; 11 (19.2%) had CoA postnatally. A significant linear relationship was identified between ventricular discrepancy degree and FOF prominence (P<0.001, R=0.48). A significant linear relationship was also identified between the RFOF and disproportion of the great arteries (P<0.001, R=0.42). FOF prominence significantly differed between groups true positive and false positive (P<0.001). RFOF occurred significantly differently in the true positive and false positive groups (56.5% vs. 0.91%, P=0.002). Cardiac parameters, including the aortic valve (AO) z-score (P=0.785), aortic isthmus (AOi) z-score (P=0.944), pulmonary artery (PA) z-score (P=0.693), PA/AO ratios (P=0.055), left ventricle (LV) z-score (P=0.192) and right ventricle (RV)/LV ratios (P=0.225), were comparable between fetuses with and without CoA after birth except RV z-score (P=0.035). There is no statistical difference of cardiac parameters between fetuses with and without CoA after birth except RV diameter. The proportion of fetuses with RFOF is significantly greater in patients without CoA. Fetal echocardiography including bulging of the FOF in the LA should be investigated for suspected CoA to decrease false positive diagnosis of CoA.