During newborn nursery admission of a term infant, the upper-extremity systolic blood pressure is 20 mmHg higher than the lower-extremity. This finding most strongly suggests which condition?

• A. Coarctation of the aorta
• B. Patent ductus arteriosus
• C. Persistent pulmonary hypertension
• D. Hypotension due to sepsis

Answer: (A)

A noticeable difference in systolic blood pressure between the arms and legs in a newborn points to a narrowing of the aorta after the arteries that supply the upper body. This is coarctation of the aorta. The constricted segment raises resistance to blood flow to the lower body, so the arms have higher pressures while the legs receive less perfused blood, often with diminished femoral pulses. If the coarctation is ductus-dependent, keeping the ductus arteriosus open with prostaglandin E1 may be necessary to maintain systemic perfusion until repair. Other conditions don’t produce this specific arm-to-leg pressure gradient: a PDA typically causes changes in pulse pressure rather than a consistent interlimb gradient, persistent pulmonary hypertension affects lung circulation and oxygenation rather than a limb-by-limb BP difference, and sepsis-related hypotension is a generalized low BP without a distinct upper-limb–lower-limb gradient.