The ductus arteriosus is a blood vessel connecting the pulmonary artery and the aorta. Before birth, this vessel allows the baby’s blood to bypass the lungs because oxygen is supplied by the mother through the placenta. The ductus arteriosus should close soon after birth. If it does not, it is called a patent (open) ductus arteriosus, or PDA. A PDA may be treated either with medication or surgery.
