Predictive factors of outcome and observation period in children with unilateral hydronephrosis which caused by ureteropelvic junction obstruction

Objective To evaluate the observation period and association between the initial visit data including initial APD measured by ultrasonography (USG) and outcome of unilateral hydronephrosis caused by ureteropelvic junction obstruction (UPJO) in children. Methods One hundred and ninety-three children with UPJO, who underwent the USG at the initial visit time. There were 155 boys and 38. 166 cases in left side and other 27 cases in right side. All cases were divided by initial visit time and initial APD respectively. There were 109 infancy(≤12 months), 36 toddler(12-36 months), 19 preschooler(36-60 months), 29 school-age children(>60 months)and 11 cases in normal group(APD 1.5 cm). All the patients were follow up for at least 24 months and divided into two groups depended on whether the patients received the surgery. Results Areas under the receiver operating characteristic plots were 0.924 (95%CI 0.870-0.977, P 1.5 cm was the risk factors predicting operation with the hazard ratio of 2.991 (95%CI 1.328-6.734, P=0.008) and 16.593 (95%CI 5.893-46.719, P 1.5 cm, initial APD≤1.5 cm, infancy and after infancy, were 43.20%(35/81), 2.67%(3/112), 30.27%(33/109), 5.95%(5/84), respectively. Conclusions Initial USG is an efficient diagnostic tool to detect pathologic hydronephrosis. Initial APD predicts the clinical outcome of UPJO in pediatrics accurately. Further investigation is recommended when initial APD>1.5 cm. Close observation is needed during the one year after initial visit to detect the deterioration of UPJO, especially in infancy. Key words: Ureteropelvic junction obstruction; Hydronephrosis; Anteroposterior renal pelvic diameter; Clinical outcomes