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Abstract

ABSTRACT: BACKGROUND: To determine the value of secondary signs of ureteral obstruction on helical unenhanced CT in diagnosing or excluding ureteral stone disease. METHODS: Over a period of 15 months, we prospectively analysed the CT scans of 283 patients with acute flank pain for the presence of ureteral stones & associated signs of ureteral obstruction. 105 patients had no confirmatory imaging studies or surgery & were unable to be contacted for follow up .These were excluded from the study. In the remaining 178 patients confirmatory data were availabe & thus were included in the study. Ureteral stone disease was confirmed to be present in 114 patients & absent in 64 patients. For each patient, we determined the presence or absence of ureteral stone, ureteral or collecting system dilatation, perinephric stranding, &renal parenchymal thickening. We also noted the presence or absence of the (" tissue rim" sign) surrounding ureteral stones & extraurinary calcifications. RESULTS: Hydroureter was the sign with the highest sensitivity (92 %) & highest specificity (92%), While hydroureter had the highest specificity (95 %) & highest PPV (97%). The combination of unilateral hydroureter & unilateral perinephric stranding had both the highest PPV (98 %) & NPV (91 %) compared with any individual sign alone . The tissue rim sign was present in (57 %) of urteral stones & in none of the extraurinary calcifications. CONCLUSION: In patients having acute flank pain with suspected ureteral stone disease imaged with unenhanced CT , secondary signs including hydroureter , hydronephrosis , perinephric fat stranding , & renal parenchymal thickening are very common & provides supportive evidence that an acute obstructive process is present & that the urinary tract is likely responsible for the patients' complaints even when the ureteral stone itself could not be identified on CT .

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