Duplex scanning has a limited role in the evaluation of patients with renal failure

Although common indications for renal duplex scanning (RDS) include hypertension (HT) and renal failure (RF), the role of RDS in the evaluation of patients with RF is not known. The goal of this study was to define ultrasound findings with predictive or discriminatory value in patients with RF and to identify patients undergoing a renal artery intervention as a result of RDS findings.

We conducted a retrospective review of 214 consecutive patients referred to an Intersocietal Accreditation Commission-accredited vascular laboratory for an initial RDS from January 1, 2010, to June 30, 2010. RDS included direct ultrasound evaluation of the main renal vessels and renal parenchyma. Significant renal artery stenosis of ≥ 60% diameter reduction was indicated by a renal/aortic velocity ratio ≥ 3.5 and abnormally increased parenchymal resistance by an end-diastolic ratio ≤ 0.3.

We separated the patients into two groups by indication for RDS: Group I (HT alone, n = 102) and group II (RF alone or with HT, n = 112). When group I was compared with group II, there were significant differences in gender (50% vs 67% male; P = .013), age (50.9 ± 18.5 vs 60.0 ± 14.8 years; P < .001), mean arterial pressure (103.1 ± 18.8 vs 85.7 ± 17.0 mm Hg; P < .001), and creatinine (0.95 ± 0.35 vs 2.25 ± 1.07 mg/dL; P < .001). In group I patients, 86 (84.3%) had normal parenchymal resistance, whereas in group II patients, 68 (60.7%) had abnormally increased parenchymal resistance unilaterally or bilaterally (P < .001). Unilateral or bilateral renal artery stenosis was identified in six group I patients and in three group II patients (P = .315). Evaluation of group II patients revealed a diagnosis of decompensated congestive heart failure (CHF) and the presence of unilateral or bilateral increased parenchymal resistance in 27 of 68 (39.7%) vs nine of 44 (20.4%) with CHF and normal parenchymal resistance. One renal artery angioplasty was performed in a patient with unilateral renal artery stenosis and fibromuscular dysplasia.

Renal artery stenosis is extremely uncommon in patients undergoing RDS for RF, indicating that ischemic nephropathy is rarely a cause of RF in these patients. Abnormally increased renal parenchymal resistance is frequently found in patients being evaluated for RF and is associated with increasing creatinine and age. A diagnosis of CHF is also more common in patients with increased parenchymal resistance. Although patients who undergo RDS for RF rarely require renal artery interventions, ultrasound indices of parenchymal resistance may serve as a marker for renal disease and cardiovascular morbidity. Further studies are required to determine the prognostic significance of these ultrasound findings in the setting of RF.