The role of micturating cystourethrography in antenatally detected mild hydronephrosis

The postnatal imaging of infants with antenatally detected mild hydronephrosis remains controversial. Our aim was to establish the role and timing of micturating cystourethrography (MCUG) in mild hydronephrosis. We performed a retrospective study of 61 infants (122 kidneys) referred with an antenatal diagnosis of hydronephrosis who showed persistent postnatal dilatation. All had follow-up postnatal ultrasound (US) and MCUG performed. The degree of dilatation at each follow-up scan was recorded. Of the 122 kidneys, 65 showed mild hydronephrosis. A substantial proportion of these (21.5%) demonstrated reflux. Serial US of these infants showed that the 6-week scan was the most informative and that any changes that warranted further investigation had occurred by this time. We recommend that all infants with mild hydronephrosis should undergo MCUG. MCUG need not be delayed until 3 months but could be performed following a 6-week US scan.