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Ductus arteriosus closure — MRCPCH TAS MCQ

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ModeratePhysiologyDuctus arteriosus closureMRCPCH TAS

A healthy term newborn has a ductus arteriosus that constricts after birth. Oxygen saturation rises and placental prostaglandin supply stops. What is the most likely mechanism?

Educational content. Not a substitute for clinical judgement or local policy.

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Correct answer: E — Increased oxygen tension and reduced prostaglandin E2

Functional ductal closure follows increased arterial oxygen tension and falling prostaglandin E2 after delivery. Increased pulmonary vascular resistance would favour persistence of fetal shunts rather than closure. The teaching point is that prostaglandin infusion can maintain ductal patency in duct-dependent congenital heart disease.

Reference: Ganong's Review of Medical Physiology; Nelson Textbook of Pediatrics; RCPCH Theory examination syllabi