The Accuracy of Doppler Ultrasonography in the Followup of Pyeloplasty for Congenital Pelviureteric Junction Obstruction

Abstract

BACKGROUNDCongenital pelviureteric junction obstruction (PUJO) is a common condition needing surgery for the improvement of renal function. Followup after surgery requires imaging modalities involving radiation exposure. Doppler sonography is an alternative, which can avoid radiation.The aim of this study is to evaluate the accuracy of Doppler ultrasonography in the followup of patients with pelviureteric junction obstruction (PUJO) undergoing open pyeloplasty. Setting and Design-This prospective observational study was conducted in a tertiary care teaching hospital. MATERIALS AND METHODSThis study comprised of 31 patients with unilateral PUJO, who underwent open pyeloplasty. The diagnosis of PUJO was made by findings on IVU or diuretic renogram. The Renal Resistive Index was evaluated using Duplex Doppler ultrasonography. A renal RI >0.7 was considered diagnostic of obstruction. Resistive Index Ratio was calculated as the ratio of RRI of obstructed to that of opposite kidney. RIR value more than 1.11 was considered as obstruction.All patients were followed up with Doppler at 3 months after surgery and the RRI value was measured. DTPA renogram was repeated at 3 months after surgery. The data was collected and sensitivity and specificity of Doppler as a diagnostic test wa s calculated using DTPA renogram as the standard. RESULTSAmong the 31 patients, preoperative renogram showed obstruction in 19 patients and equivocal result in 12 patients. Doppler ultrasonography showed obstruction in 16 of the 19 patients with obstructive renogram. RRI of the opposite kidney showed nonobstructive value in all patients, as did the renogram. Preoperative RIR value showed obstruction in 17 out of 19 patients. Among the 12 patients with equivocal pattern who underwent pyeloplasty, preoperative RRI was suggestive of obstruction in 8 patients, while RIR showed obstruction in 9 patients. Postoperative renogram showed non-obstructive pattern in 29 patients and obstruction in 2 patients. Twenty eight out of the 29 patients with relieved obstruction had RRI < 0.70, while 1 patient showed persistently elevated RRI as well as RIR. CONCLUSIONRenogram is useful for the followup of patients who have undergone pyeloplasty and for monitoring patients with hydronephrosis under observation.