Management dilemma in pelvi-ureteric junction obstruction: is transit time the answer?

Pelvi-ureteric junction obstruction (PUJO) is the leading cause for hydronephrosis in children. Diuretic renography used in the pre- and post-operative evaluation of pyeloplasty may not be reliable in predicting the outcome.

A prospective study was conducted from October 2018 to November 2020, including all children with unilateral PUJO undergoing Pyeloplasty. Renal diuretic renography scans done in the pre and post operative periods were assessed for transit time. The time taken for the isotope to reach the renal pelvis was noted by a single observer as the transit time, from the dynamic frames of the diuretic renogram.

Of the 65 children, 74% were boys. The transit time (median) in the preoperative renography was 10 min, whereas the same was 4 min 45 s in the postoperative period, the decrease was statistically significant. On evaluation of transit time with ROC (receiver operating characteristics) curve, a cut-off of 4 min and 25 s was arrived at, which could identify the delayed drainage reliably.

Improvement in transit time is a reliable predictor of renal function improvement after pyeloplasty, comparing favorably in relation to split renal function.