Renal perfusion in dynamic scans: a key predictor of long-term outcomes in posterior urethral valves.

Background: Nadir creatinine value is used as a key predictor of long-term kidney outcomes in patients with posterior urethral valves (PUV). This study explores the role of kidney perfusion status in dynamic renal scans as an additional predictor of future kidney outcome of these patients.

Methodology: A prospective observational study was conducted over 2 years in a tertiary referral centre, involving patients above 2.5 years of age who followed a uniform bladder management protocol. Serial eGFR measurements were recorded and correlated with serum creatinine levels, nadir creatinine, episodes of urinary tract infection (UTI), and renal perfusion status as determined by renal dynamic scans.

Results: Out of 112 patients, two-thirds presented during infancy. Mean age at first eGFR assessment was 6.17 ± 2.8 years. Creatinine at presentation and nadir creatinine varied significantly among the four perfusion groups (p = 0.003), with the highest creatinine levels observed in patients where the better-perfused kidney had poor perfusion. UTI episodes during follow-up were strongly associated with renal perfusion status (p = 0.003), with the highest incidence occurring in patients with impaired perfusion in their worse kidney. eGFR values also differed significantly across perfusion groups (p < 0.001). The eGFR at second follow-up (n = 81) was improved or static in patients with at least one renal unit well perfused while it declined progressively in patients with impaired perfusion of kidney units.

Conclusion: This study highlights the value of renal dynamic scans in predicting renal reserve and long-term outcomes in patients with PUV. It also sheds light on the increased frequency of follow-up UTIs and the prolonged need for bladder management in specific patient subsets.