Innes et al [16] report that patients with renal colic and with absent to mild hydronephrosis were deemed less likely to have stone passage failure and therefore do not need further imaging, although they note that CT can be useful in the setting of renal colic with moderate to severe hydronephrosis by US because these patients can be at higher risk of stone passage failure. CT is also better able to identify nonurolithiasis findings requiring additional management than US [25]. Pathan et al [22] reviewed 651 patients with POCUS and CT in the setting of renal colic, finding that moderate to severe hydronephrosis on POCUS examination in patients with moderate or high risk of ureteric calculi, provided a more definitive answer regarding the presence of a stone without the need for high-dose CT scanning. In such patients, they advised a low-dose CT scan if the size and location of the stone is desired to plan surgical management. One prospective study of 46 patients with renal colic, documented ureteral stones, and identifiable ureterovesical jet investigated differences in color Doppler US after oral hydration between these presumed obstructed ureters and their nonobstructed contralateral counterparts, finding significant differences of jet frequency, duration, and peak velocity [41]. Renal and ureteral US with color Doppler can identify calculi as well as hydronephrosis in patients with renal colic, although patients who undergo US for initial evaluation are at increased likelihood of undergoing additional imaging [17]. In a prospective study of 206 patients with renal colic and suspected urolithiasis, Faget et al [35] found that the combination of radiography of the abdomen and pelvis and US enabled identification of 50% of the stones that had been identified via CT and 68% of the stones treated by urological procedures. Variant 4: Adult. Asymptomatic hydronephrosis in a pregnant patient with unknown cause. Initial imaging.
Hydronephrosis on Prior Imaging Unknown Cause. Innes et al [16] report that patients with renal colic and with absent to mild hydronephrosis were deemed less likely to have stone passage failure and therefore do not need further imaging, although they note that CT can be useful in the setting of renal colic with moderate to severe hydronephrosis by US because these patients can be at higher risk of stone passage failure. CT is also better able to identify nonurolithiasis findings requiring additional management than US [25]. Pathan et al [22] reviewed 651 patients with POCUS and CT in the setting of renal colic, finding that moderate to severe hydronephrosis on POCUS examination in patients with moderate or high risk of ureteric calculi, provided a more definitive answer regarding the presence of a stone without the need for high-dose CT scanning. In such patients, they advised a low-dose CT scan if the size and location of the stone is desired to plan surgical management. One prospective study of 46 patients with renal colic, documented ureteral stones, and identifiable ureterovesical jet investigated differences in color Doppler US after oral hydration between these presumed obstructed ureters and their nonobstructed contralateral counterparts, finding significant differences of jet frequency, duration, and peak velocity [41]. Renal and ureteral US with color Doppler can identify calculi as well as hydronephrosis in patients with renal colic, although patients who undergo US for initial evaluation are at increased likelihood of undergoing additional imaging [17]. In a prospective study of 206 patients with renal colic and suspected urolithiasis, Faget et al [35] found that the combination of radiography of the abdomen and pelvis and US enabled identification of 50% of the stones that had been identified via CT and 68% of the stones treated by urological procedures. Variant 4: Adult. Asymptomatic hydronephrosis in a pregnant patient with unknown cause. Initial imaging.