Ductus arteriosus
The mid-trimester fetal heart has been turned to the right to photograph the ductus arteriosus (*). Note that, in the
fetus, the ductus is a continuation of the pulmonary trunk. The right and left pulmonary arteries are small because
only a small amount of blood flow goes through the fetal lungs. Arrow points to the right pulmonary artery.
1 minute clinical correlation