Abnormal fetal cardiovascular morphology Foramen ovale aneurysm 2022-02-01T17:07:42Z Redundant septum primum flap Foramen ovale aneurysm (FOA) or atrial septal aneurysm is abnormal redundancy of the atrial septum primum, with bulging of the septum by at least half the width of the atrial chamber, or by at least 10 mm beyond the level of the atrial septum. The abnormal protrusion of the interatrial septum results in decreased left atrial volume. On color Doppler there is reduced left ventricular inflow. Foetal atrial septal dilatation The reported incidence of foramen ovale aneurysm (FOA) in preterm and term infants is 11.1% and 7.1%, respectively. Postnatally, most atrial septal aneurysms resolve spontaneously as the pressure in the left atrium increases and compresses the septum against the foramen ovale. However, atrial septal aneurysms may be associated with other cardiac anomalies including atrial septum defect, patent foramen ovale, and mitral valve prolapse. In the absence of other cardiac anomalies or arrhythmia, the prognosis for FOA is excellent. See figure 7 of PMID:30601441. Fetal atrial septal dilatation