RIGHT PYELOCALICEAL DUPLICATION WITH FUNCTIONAL EXCLUSION OF THE LOWER MOIETY AND SIGNS OF REFLUX: APPLICATION OF 99MTC-DTPA RENAL SCINTIGRAPHY IN COMPLEX FUNCTIONAL ASSESSMENT

Introduction : Congenital anomalies of the urinary tract account for 30–50% of chronic kidney disease causes in the pediatric population. Pyelocaliceal duplication is one of the most frequent malformations and may present with ureteral ectopia, obstruction, or vesicoureteral reflux (VUR), directly affecting renal function. Dynamic renal scintigraphy with 99mTc-DTPA plays a key role in evaluating glomerular function and diuretic response, particularly in complex cases such as the one reported here, in which vesicoureteral reflux on the right side was demonstrated during the excretory phase. Materials and methods : A 16-year-old patient with right pyelocaliceal duplication, a history of grade IV right-sided VUR, multiple urologic surgeries, recurrent urinary tract infections, and stage 3A chronic kidney disease. 99mTc-DMSA scintigraphy revealed functional asymmetry (right kidney 21%, with lower moiety exclusion) and bilateral cortical scars. Dynamic renal scintigraphy with 99mTc-DTPA showed reduced arterial flow and function in the upper moiety and absence of function in the lower moiety. Partial tracer retention was observed up to the 25th minute in both kidneys, with good response to furosemide. During the late dynamic phase, vesicoureteral reflux of the tracer to the right lower moiety became evident, accentuated after diuretic administration. Discussion : Diuretic-enhanced dynamic renal scintigraphy with 99mTc-DTPA is considered the gold standard for evaluating upper urinary tract obstruction. As the tracer is purely glomerularly filtered, it allows functional and excretory drainage assessment. Studies show that about 10% of patients with complete renal duplication progress to functional loss in one moiety, and early detection of such exclusion can prevent unnecessary interventions. 99mTc-DTPA scintigraphy also enables indirect identification of vesicoureteral reflux even without cystography, as in this case, where reflux of the tracer into the functionally excluded moiety supported the diagnosis and guided therapeutic decisions. Conclusion : This case demonstrates the importance of dynamic renal scintigraphy with 99mTc-DTPA in assessing renal function in complex urologic malformations. The identification of functional exclusion of the lower moiety and vesicoureteral reflux was fundamental in multidisciplinary management and treatment planning.