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 Rrl) allows different interpretations of the diuretic renogram and may affect the treatment of these children.