Objective: Ureteropelvic junction obstruction (UPJO) is one of the most principal cause of renal damage in children. It is very difficult to determine the most suitable time for surgery in patients with high grade obstruction. Diuretic Tc-99m diethylenetriamine pentaacetic acid (DTPA) scintigraphy is the most widely used method for diagnosis and follow up of UPJO. The aim of our study was to evaluate DTPA scintigraphy parameters in children with UPJO.

Material and Method: The children which were followed up with UPJO during the period 2000-2010 retrospectively were evaluated. Diuretic Tc-99m-DTPA scintigraphy was performed on all patients. Patients who have bilateral disease, renal pelvic anteroposterior (AP) diameter >40 mm, split renal function less than 40% significantly increasing hydronephrosis, significantly decreasing split function and clinical symptoms were treated with surgery. All patients were followed with serially renal ultrasonography and 99mTc-DTPA renography at 3 and 6 months after the operation.

Results: In our study, 48 cases with UPJO were evaluated. Pelvis AP diameters were higher in patients selected for pyeloplasty than in the patients with no operation (p=0.0001). AP diameters of operated patients [14 (93.3%) of 15] were regressed after operation (30.5±11.7 mm vs. 15.4±10.4 mm, p=0.0001). Regression ratios of AP diameters were 56.44% in these patients. Mean regression time were 10.23±6.02 months. T1/2 in DTPA were higher in operated patients than those of non-operated patients but baseline RF were similar in these groups (p=0.038 and p>0.05, respectively). After pyeloplasty, DTPA T1/2 time were improved (22.3±3.4, 14.0±0.9 respectively, p=0.011). RF were also increased after surgical treatment (Renal function 39.2% ± 2.5 / 43.4±1.4, p=0.012).

Conclusion:<7b> T1/2 time is a useful marker that can be used in the follow-up and in determining the indication for surgery in children with UPJO. Also, split renal function could be used after the surgery in follow-up rather than in determining the optimal time for surgery in children with UPJO.