SURGERY VERSUS OBSERVATION FOR MANAGING OBSTRUCTIVE GRADE-3 TO GRADE-4 UNILATERAL HYDRONEPHROSIS - A REPORT FROM THE SOCIETY FOR FETAL UROLOGY

Purpose: The Society for Fetal Urology has undertaken the first multic enter prospective randomized study of high grade obstructive unilatera l hydronephrosis to evaluate the natural history of untreated obstruct ion and compare it to the benefits of pyeloplasty. Materials and Metho ds: Since 1991, infants with isolated unilateral Society for Fetal Uro logy grade 3 hydronephrosis and ipsilateral obstruction with greater t han 40% differential renal function on well tempered renography were s tudied. Patients were randomly assigned to observation or pyeloplasty groups. Renal ultrasound and well tempered renography were performed b iannually for 1 year and yearly thereafter. Crossover criteria for sur gery included concurrent worsening of isotope washout and increasing g rade of hydronephrosis or a greater than 10% point loss in percent dif ferential renal function that was noted between studies. The end point of the study was the 3-year anniversary of randomization. Results: A total of 32 infants from 10 centers were randomized equally to 2 group s. The starting grade of hydronephrosis and percent differential renal function were similar between the 2 groups. At 6 months and 1 year th e grade of hydronephrosis was significantly reduced (p < 0.02) and wel l tempered renography was significantly more likely to demonstrate no obstruction (p < 0.03) in the surgical group compared with the observa tion group. The mean percent differential renal function remained stab le and similar in both groups. Reduced hydronephrosis and resolution o f obstruction in the surgery group persisted as a trend at the 2 and 3 -year anniversaries. In the observation group 4 patients (25%) showed enough renal deterioration to qualify for crossover to surgery. Conclu sions: Infant pyeloplasty significantly improved the grade of hydronep hrosis and drainage pattern at 6 months and 1 year postoperatively, wh en compared with observation. Renal function stabilization was similar for either management approach. However, 25% of the patients satisfie d objective criteria of status deterioration requiring pyeloplasty.