Correlation between Doppler sonography and diuretic renogram in the diagnosis and follow-up of infants with unilateral pelvi-ureteric junction obstruction

Background Conventionally, diuretic isotope renogram is used to establish and quantify severity of the obstruction in pelvi-ureteric junction obstruction. Doppler ultrasonography too assesses obstruction by evaluating the resistive index (RI) and resistive index ratio (RIR) in the intrarenal vasculature of the kidneys. This study aimed to note correlation between RI, RIR on Doppler ultrasonography and perfusion index (PI) on diuretic isotope renogram in suspect unilateral pelvi-ureteric junction obstruction in infants. A prospective study (2016-2019) in infants with suspect unilateral hydronephrosis, i.e. anteroposterior pelvic diameter (APPD) > 15 mm, divided into Group A (0-6 months) and Group B (6-12 months) based on the age at diagnosis. The RI, RIR and PI were noted at diagnosis, at 3 and 6 months, post-interventions and the correlation assessed. Results37/94 with hydronephrosis were included in the study. 30 among these underwent surgical intervention. A decrease in RI and RIR and increase in PI following surgery were documented at follow-up. Also, the improvement was statistically more significant in the first 3 months following intervention. Conclusions An increased RI and RIR and a decreased PI are good indicators of obstruction in unilateral hydronephrosis in infants. The decline in RI with increase in PI following relief of obstruction shows a positive correlation between the two. Doppler sonography may be effective in monitoring unilateral hydronephrosis with unobstructed or equivocal renogram curves and consequently negate the need for repeated nuclear scans.