The Usefulness of Unenhanced Helical CT in Patients with Acute Flank Pain in the Emergency Room

Sung, Won Sub; Yang, Sang Kuk; Kim, Hong Sup; Lho, Yong Soo; Shin, Hyun Joon

Abstract

PURPOSE
We prospectively evaluated the usefulness of unenhanced helical computerized tomography (UCT) in patients with acute flank pain in the emergency room.
MATERIALS AND METHODS
Between March and July 2001, 57 patients, visiting the emergency room with acute flank pain suggestive of urinary stone by physical examination, urine analysis, plain abdominal radiology (KUB) and clinical history, underwent UCT. This UCT study was evaluated for the presence or absence of urinary stones and secondary signs of ureteral obstruction on UCT (tissue-rim sign, hydronephrosis, hydroureter, strands of perinephric fat). The findings of UCT and intravenous pyelography (IVP) were compared for the presence or absence of ureteral obstruction and delineation of urinary stones according to their sizes and locations. The reading accuracy of urinary stones on UCT of one urologic resident was compared with that of one member of the radiologic staff.
RESULTS
Fifty-two of the 57 patients had one or more urinary stones. UCT depicted 66 of 68 stones in the 52 patients. The sensitivity and specificity of UCT were 97% and 100%, respectively. Two cases of urinary stones, which were identified by ureteroscopy and spontaneous passing, couldn't be found on UCT, but hydronephrosis was identified. IVP disclosed 55 of 68 stones, with a sensitivity and specificity of 80% and 83%, respectively. In secondary signs of ureteral obstruction on UCT, stones above 4mm in size showed more frequent secondary signs of ureteral obstruction on UCT than those below 4mm in size. The reading accuracy of the urologic resident improved during the period, being 57% in the first half and 83% in the second half.
CONCLUSIONS
UCT was an accurate, safe, and rapid technique to assess acute flank pain in the emergency room. The reading ability to diagnose ureter stones in UCT films required an adequate learning curve. Because not all stones could be identified with UCT, it would not completely replace IVP.