Which finding most strongly suggests Tetralogy of Fallot in a child?

• A. Murmur
• B. History of squatting
• C. Bounding pulses
• D. Cyanosis

Answer: (D)

Tetralogy of Fallot causes a right-to-left shunt because of obstruction of the right ventricular outflow tract combined with a VSD, leading to decreased blood flow to the lungs and mixing of desaturated blood into the systemic circulation. That results in cyanosis, which is the most specific and strongest clue among the options for TOF in a child. The squatting history is common and helps relieve episodes by increasing systemic vascular resistance, but it isn’t universal and isn’t as definitive as the presence of cyanosis. A murmur can occur from the RVOT obstruction, but it isn’t diagnostic on its own. Bounding pulses suggest increased pulmonary flow from left-to-right shunts and are not typical of TOF. So the finding that most strongly points to TOF is cyanosis.