Ultrasound as a diagnostic tool to differentiate acute from chronic renal failure

Renal ultrasound (US) is the most appropriate method for imaging renal failure; however, considerable overlap in renal size and renal echogenicity exists between normally and abnormally functioning kidneys. We compared the sonographic features of kidneys in patients with renal failure to investigate the potential role of renal US to distinguish acute from chronic renal failure and assessed the diagnostic role of body surface area-corrected renal length compared to measured renal length.

We included 127 consecutive patients with serum creatinine levels higher than 3 mg/dl and 33 healthy volunteers. The subjects with acute renal failure (ARF) and chronic renal failure (CRF) were compared for renal length, parenchymal thickness, parenchymal echogenicity, distinctness of the corticomedullary junction, and the presence of stones and cysts.

No significant differences in age, serum albumin, creatinine, weight, height, or gender distribution were found between patients with ARF and those with CRF, except in serum hemoglobin. The right and left kidney parenchymal thickness and renal length were significantly greater in ARF patients than in those with CRF (p < 0.0001). The mean parenchymal thickness and renal length were similar in ARF patients and the control group. Grade I hyperechogenicity was the most common finding during sonography.

Renal length, parenchymal thickness, and echogenicity differed significantly between patients with acute and chronic renal failure. A renal US examination is still the most appropriate method for imaging renal failure and should be combined with other tests to distinguish acute from chronic renal failure.