Persistent fetal circulation is best defined as which?

• A. The fetal circulation through the heart persisting after birth
• B. The heart failing to open the foramen ovale after birth
• C. Rapid closure of the ductus arteriosus after birth
• D. Neonatal respiratory distress syndrome

Answer: (A)

Persistent fetal circulation reflects the newborn’s failure to complete the normal transition from fetal to neonatal circulation. In the fetus, the lungs are not used for gas exchange, so blood is routed through fetal channels like the foramen ovale and ductus arteriosus, and pulmonary vascular resistance is high. After birth, the lungs expand, pulmonary resistance drops, and these shunts typically close so blood goes through the lungs for oxygenation. When this transition doesn’t occur, the fetal pattern persists after birth, with continued right-to-left or intracardiac shunting and often severe hypoxemia. That’s why the best definition is the fetal circulation through the heart persisting after birth. The other options describe different scenarios—failure to open the foramen ovale, rapid ductus arteriosus closure, or neonatal respiratory distress syndrome—none capture the idea of ongoing fetal circulation and shunting after birth.