Sonography vs. excretory urography in acute flank pain.

A prospective study compared the diagnostic accuracy of sonography and excretory urography in determining the cause of acute flank pain in 61 patients. Forty-one patients had urinary tract stone disease. Of these, five had nonobstructing renal stones and 36 had obstructing stones. A correct diagnosis was made by urography in 85% and by sonography in 66%. Small stones at the ureterovesical junction were more accurately diagnosed by sonography (79%) than by urography (68%). In all the patients where sonography failed to detect the offending stone, the stone was calcified and evident on the plain radiographs. There were no false-positive diagnoses in the patients clinically judged to have passed a renal stone (nine patients) or whose pain was arising outside of the urinary tract (five patients). Neither sonography (17%) nor urography (50%) was accurate in diagnosing acute pyelonephritis in the six patients with this diagnosis. Although sonography is not as accurate overall as urography in acute flank pain, it is a viable alternative in those with recurrent renal colic due to stone disease and in the pregnant patient.