Evaluation of sonographic renal parenchymal area in the management of hydronephrosis

Purpose: We used quantitative parameters of renal sonography to differentia te children with significant obstruction requiring surgical intervention fr om those without significant obstruction who were followed conservatively. Materials and Methods: We retrospectively reviewed the records of children who underwent evaluation for hydronephrosis. Those with a history of vesico ureteral reflux, anatomical abnormalities or neurogenic bladder were exclud ed from study. Patients were divided according to hydronephrosis grade into groups 1-grades III and IV followed conservatively, 2-grades III and IV re quiring surgical intervention, 3-unilateral grade II and 4-bilateral. All i mages were scanned into a computer. Renal parenchymal and pelvic area was d etermined using National Institutes of Health image software. Parenchymal-t o-pelvic area ratios were calculated from all images. We evaluated the abil ity of these measurements to determine the likelihood of surgical intervent ion. Results: The records of 81 children were available for analysis. Deteriorat ion in parenchymal area growth was a predictor of surgical intervention. Su ch patients had catch-up growth of the affected kidney after pyeloplasty. A parenchymal-to-pelvic area ratio of greater than 1.6 on the initial ultras ound study after birth predicted cases that would need pyeloplasty in the f uture (p <0.05). No patient with grade II hydronephrosis required surgical intervention. Conclusions: Following serial parenchymal area on serial ultrasound is usef ul for evaluating children with hydronephrosis. Those with a parenchymal ar ea below the nomogram for growth usually require pyeloplasty. A parenchymal -to-pelvic area ratio of less than 1.6 on the initial ultrasound study afte r birth in patients with prenatally diagnosed ureteropelvic junction obstru ction or on initial ultrasound in those diagnosed postnatally indicated the need for surgical intervention in this limited series.