Accuracy of Sonography in the Diagnosis of Urinary Tract Calculi Compared with Non-Contrast CT Scan

This study was designed to determine sensitivity، specificity، PPV (positive predictive value)، NPV (negative predictive value) and accuracy of sonography in comparison to non-contrast CT scan for diagnosis of urinary tract calculi. Subjects and Total 131 patients with urinary calculi detected by noncontrast CT scan underwent sonography on the same day without bowel preparation and in blinded fashion from Sep 2011 to March 2012. CT scan and sonography findings including location and size of stones were gathered. The sensitivity، specificity، PPV، NPV and accuracy of sonography in detection of caliceal calculi were 91. 7%، 72. 9%، 80. 5%، 87. 8% and 83. 2 %، respectively. The sensitivity، specificity، PPV، NPV and accuracy of sonography in detection of renal pelvis calculi were 85. 7، 100، 100، 97. 3 and 97. 7 %، respectively. The sensitivity، specificity، PPV، NPV and accuracy of sonography in detection of ureter calculi were 53%، 93. 8%، 89. 7%، 66. 3% and 73. 3 %، respectively. The sensitivity، specificity، PPV، NPV and accuracy of sonography in detection of bladder calculi were 84. 6%، 100%، 100%، 98. 3% and 98. 5 %، respectively. The sensitivity، specificity، PPV، NPV and accuracy of sonography in comparison to CT scan، for detection of all urinary tract calculi were 78. 7%، 91. 7%، 91. 9%، 87. 4% and 88. 2 % respectively. Sonography is a reliable method in detection and confirmation of renal pelvis and bladder stones but is not reliable for detection of ureter and caliceal stones. Overall results show that sonography is the safe and first method for detection of renal calculi. However multislice CT scan remains second choice if sonography results are not sufficiently clear in patients with clinical doubt of ureter and caliceal of <3mm stones