MAG3 – antenatal hydronephrosis — RACP Paediatrics MCQ

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ModerateNephrologyMAG3 – antenatal hydronephrosisRACP Paediatrics

A 3-month-old boy has antenatal hydronephrosis (APD 15 mm on postnatal day 5 ultrasound). He is well with no UTI history. What is the most appropriate next imaging investigation to assess for obstruction?

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Correct answer: A — MAG3 renogram

MAG3 renogram (diuretic renography) is the investigation of choice to assess the significance of hydronephrosis by evaluating differential renal function and drainage. It distinguishes obstructive from non-obstructive hydronephrosis. A split function <40% or poor drainage after frusemide suggests significant obstruction requiring surgical consideration (pyeloplasty for PUJO).

Reference: RCH Melbourne – 2023 – Antenatal Hydronephrosis CPG; RACP Paediatric Curriculum – Nephrology