Prenatal diagnosis of hydronephrosis: Impact on renal function and its recovery after pyeloplasty

Purpose: We reviewed our experience with corrective surgery for congenital ureteropelvic junction obstruction to assess the impact of mode of presenta tion on renal function at diagnosis and on postoperative recovery of functi on. Materials and Methods: We reviewed the records of consecutive children who underwent pyeloplasty or nephrectomy for ureteropelvic junction obstruction during a Ei-year period at our hospitals. Patients were divided into those with and without a prenatal diagnosis of hydronephrosis. In each group we compared preoperative and postoperative differential renal function, as mea sured by nuclear renography. Results: We identified 89 patients, of whom 51 (57%) and 38 (43%) presented with prenatal and postnatal hydronephrosis, respectively. Kidneys in which hydronephrosis was diagnosed prenatally had better average differential re nal function than those in which the condition was detected postnatally (45 versus 37%). This difference was even more significant in kidneys with les s than 40% initial function (31 versus 21%). Presentation with a palpable m ass was associated with worst renal function (mean 23%). Postoperatively re nal function did not recover significantly in either group. There was a min imal increase in postoperative differential renal function in the subgroup of patients in whom initial differential renal function was less than 40%, although there was no significant difference in the 2 groups (6.5 versus 4. 8%). Conclusions: The early diagnosis of hydronephrosis provided by prenatal ult rasonography is associated with less obstructive nephropathy. Prolonged fol lowup is necessary for studies of the natural history of hydronephrosis bec ause relevant obstruction manifests clinically years later. Despite success ful pyeloplasty function recovery is minimal in kidneys with poor function and hydronephrosis diagnosed prenatally. Our findings do not support previo us observations that poor function markedly improves after obstruction is r elieved.