What is the likely outcome if a mother with AIDS gives birth to a child with respiratory distress and a patent ductus arteriosus (PDA)?

The likely outcome of a mother with AIDS giving birth to a child with respiratory distress and a patent ductus arteriosus (PDA) is a left-to-right shunt. In the context of a PDA, the ductus arteriosus, which connects the pulmonary artery to the aorta in fetal circulation, remains open after birth instead of closing as it normally should.

When the ductus arteriosus is patent, blood can flow from the higher-pressure aorta into the lower-pressure pulmonary artery, which constitutes a left-to-right shunt. This abnormal flow leads to an increased volume of blood in the pulmonary circulation, potentially causing pulmonary congestion or edema, which may contribute to respiratory distress in the newborn.

In summary, the presence of a PDA creates a situation where there is an abnormal shunting of blood leading to complications such as the child's respiratory issues. This helps clarify why a left-to-right shunt is the correct outcome associated with a patent ductus arteriosus, especially in the context of the other options provided.