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PPHN – pre-post ductal difference — RACP Paediatrics MCQ

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ModerateRespiratoryPPHN – pre-post ductal differenceRACP Paediatrics

A term neonate develops severe cyanosis and respiratory failure within hours of birth. SpO2 shows a pre-post ductal saturation difference of >10% (right hand 92%, left foot 75%). Echocardiogram shows right-to-left shunting at PDA and foramen ovale with structurally normal heart. What is the most likely diagnosis?

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Correct answer: D — Persistent pulmonary hypertension (PPHN)

A significant pre-post ductal saturation gradient (>5-10%) in a term neonate with structurally normal heart indicates right-to-left shunting through fetal channels due to persistent pulmonary hypertension of the newborn (PPHN). Causes include MAS, sepsis, CDH, and idiopathic. Management includes optimising oxygenation/ventilation and inhaled nitric oxide.

Reference: RCH Melbourne – 2023 – PPHN CPG; RACP Paediatric Curriculum – Neonatology