Sensitivity of digital abdominal radiography for the detection of ureter stones by stone size and location.

OBJECTIVE

To assess the sensitivity of digital abdominal radiography in the detection of ureteral stones by stone size and location.

MATERIALS AND METHODS

We retrospectively reviewed the digital abdominal radiography of 163 patients for the detection of ureteral stones. Each ureteral stone was confirmed by unenhanced computed tomography (CT) in the emergency department between January and December, 2009. Stone location was defined as proximal or distal by the level where the ureter crossed anterior to iliac vessels, and the stone size was defined as small if smaller than 5 mm and large if larger than 5 mm on unenhanced CT. The interpretation of digital abdominal radiography was classified as visible, invisible, or equivocal.

RESULTS

In 163 ureteral stones, 77 stones (47.2%) were in the proximal ureter and 86 stones (52.8%) were in the distal ureter. The mean (SD) size of the ureteral stones was 3.4 (1.7) mm (range, 1-9 mm). Overall sensitivity of digital radiography for ureteral stones was 29.4%. The sensitivity of digital radiography for the proximal ureteral stones was 37.7% and that for the distal ureteral stones was 22.1% (P < 0.05). The sensitivity of digital radiography for small ureteral stones was 23.6% and that for large ureteral stones was 50.0% (P < 0.05). As a group, the sensitivity of digital radiography for large proximal ureteral stones was the highest sensitivity-72.2%-in all groups (P < 0.05).

CONCLUSION

Digital abdominal radiography is useful in detecting large proximal ureteral stones.