Renal colic: the role of ultrasound in initial evaluation.

A prospective sonographic study of 21 patients with suspected renal colic was undertaken to detect the presence or absence of urinary tract calculi. The presence of calculi was diagnosed sonographically by visualization of the calculus and/or unilateral hydronephrosis in all 18 cases in which presence of a calculus was subsequently proved by surgery, spontaneous passage and recovery, or intravenous urography. In the two cases in which the sonographic examination demonstrated neither calculi nor unilateral obstruction, further evaluation confirmed the absence of calculi. There was one false-positive examination in which unilateral hydronephrosis was detected secondary to a retroperitoneal tumor. There were no false-negative examinations. The results of this study support the use of ultrasound in the initial evaluation of renal colic.