Diuretic renography in infants with prenatal unilateral hydronephrosis: an explanation for the controversy about poor drainage.

OBJECTIVE: To present an explanation for impaired drainage on diuretic renography in infants with a prenatal diagnosis of unilateral renal pelvic dilatation (RPD) who are stable both in terms of renal function and dilatation on follow-up investigations, despite undergoing no surgical intervention, and who undergo diuretic renography postnatally; this should provide some insight into whether impaired drainage is a sign of obstruction in these asymptomatic infants.

MATERIALS AND METHODS: Using a combination of published studies on the technique of diuretic renography and an analysis of such studies, a theoretical model of the infant kidney was developed to assess the possibility of prolonged drainage.

RESULTS: The results from the model showed prolonged drainage in many different situations, thus offering an explanation of expected impaired drainage even if there was no obstruction.

CONCLUSION: Understanding the pathophysiology of prenatally diagnosed RPD allows different interpretations of the diuretic renogram and may affect the treatment of these children.