Ultrasound asessment of the fetal foramen ovale

Abstract

Normal values for the horizontal cross section and transverse diameter of the foramen ovale outlet were established for the second half of pregnancy. In particular, the horizontal transverse diameter and its ratio to the right atrial width are easy to determine, and use of these measurements is thus suggested for the assessment of the fetal foramen ovale.

Intrauterine pulmonary venous flow and restrictive foramen ovale in fetal hypoplastic left heart syndrome

“…Similar measurements were obtained from the initial neonatal echocardiogram. The FO was considered to be restrictive in utero when the maximum diameter measured in a four-chamber view was Յ2.5 mm (Յ5th percentile for gestational age Ն20 weeks [27,28]), with continuous high-velocity flow (Ͼ60 cm/s; abnormally high peak FO velocity in the mid and third trimesters [28]). Color flow mapping was used to confirm the FO location.…”

“…To obtain the PV flow spectrum, the Doppler sample volume was placed over a PV in the lung parenchyma or at its LA junction, using color flow mapping to guide positioning (27,28). Tracings were obtained with the sample volume as parallel to the direction of blood flow as possible.…”

Ductus Venosus in the First Trimester: Contribution to Screening of Chromosomal, Cardiac Defects and Monochorionic Twin Complications

“…About 30% of the oxygenated blood from the umbilical vein, which is distributed to the portal vein, is shunted through the ductus venosus [7,8] . The degree of shunting will be determined by the diameter of the vessel, pressure gradient and blood viscosity [9] .…”

Fetal Venous Circulation

“…However, as we have discussed in a previous section, the inferior venous return constitutes a rather vertical flow that is divided in a right and left arm at the level of the crista dividens (Figure 3 and 6a). 131 Interestingly, the size of the foramen ovale is stable after 30 weeks of gestation, particularly when comparing with the IVC cross section (Figure 17). Based on these principles, the area and diameter of the foramen ovale inlet to the left atrium have been determined.…”

“…Printed with permission 131 It is worth looking at the relationship between the IVC and the foramen ovale. Blood from the abdominal inferior vena cava (light grey) enters the right atrium.…”