Postductal coarctation is located distal (after) the PDA.

• A. Proximal (before) the PDA
• B. Within the PDA
• C. Distal (after) the PDA
• D. Across the PDA

Answer: (C)

Coarctation of the aorta is described by where the narrowing sits relative to the ductus arteriosus. The ductus arteriosus connects the proximal descending aorta to the left pulmonary artery in fetal life and closes after birth to form the ligamentum arteriosum. If the narrowing occurs downstream of that connection, it is categorized as postductal (distal) coarctation. This location is typical for postductal cases, especially in older children and adults, after the ductus has closed. In contrast, preductal (infantile) coarctation lies proximal to the ductus arteriosus. So, describing the coarctation as distal (after the PDA) accurately identifies it as postductal.