Is combined ultrasound with radiography sufficient for the diagnosis of obstructive ureteric stone in patients with acute flank pain?

Abstract

Context: Ultrasound (US) is excellent for detection of hydronephrosis but has poor sensitivity for stone detection. In contrast, radiography of the kidney–ureter–bladder has better sensitivity for detection of stone but limited sensitivity for hydronephrosis detection. A combination of these two modalities may improve both sensitivity and specificity for the diagnosis of obstructive ureteric stone. Aims: This study aims to investigate the diagnostic accuracy of combined US with radiography for the diagnosis of obstructive ureteric stone in adult patients. Settings and Design: Retrospective study with retrospective data collection performed in a 1500-bed university hospital. Materials and Methods: A total of 90 patients were included. The electronic medical record, radiological reports, laboratory results, and patient management were extracted and analyzed. Statistical Analysis Used: The diagnostic performance of US, radiography, and combined US with radiography were calculated and compared. The computed tomography was used as diagnostic reference. Results: US alone had a sensitivity of 73.5%, specificity of 92.7%, and negative predictive value (NPV) of 74.5% for hydronephrosis. When US showed both ureteric stone and hydronephrosis, sensitivity dropped to 14.3% but specificity increased to 100%. Radiography alone had a sensitivity of 34.7%, specificity of 100%, and NPV of 56.2% for the detection of ureteric stone. Combining radiography with US raised the sensitivity for diagnosis of obstructive ureteric stone to 88% with a specificity of 93% and accuracy of 90%. Conclusions: Combined US with radiography was accurate for the diagnosis of obstructive ureteric stone in patients presenting with acute flank pain.

Keywords

• computed tomography
• hydronephrosis
• ultrasound
• ureteric stone