A newborn ultrasound on day four of a cesarean section with an unclosed foramen ovale is a newborn baby born with a hole in the heart between the two atria that is not completely closed. The foramen ovale allows oxygenated blood to flow from the left atrium to the left ventricle bypassing the lungs and diverting oxygenated blood from the right atrium to the left atrium during fetal life. By the time the fetus is born the pressure on the left side of the heart increases and the pressure on the right side decreases and the foramen ovale closes. Most newborns will complete functional closure after birth, and a small number of newborns will have patent foramen ovale, but as the newborn grows and develops, the foramen ovale can be closed before the age of two years, as long as there is no clinical discomfort and does not require any special treatment, and can be reviewed regularly. If the defect is larger than 5mm or causes heart failure, bronchopneumonia, etc., or is not closed after two years of age, timely surgical treatment is needed.