CT can be useful in patients with renal colic and moderate to severe hydronephrosis by US, because these patients can be at higher risk of stone passage failure [16], although some authors suggest CT should be reserved in renal colic patients for when US is nondiagnostic or when an alternative diagnosis is suspected [17]. In cases of suspected infection, it can be difficult to distinguish pyonephrosis from hydronephrosis even by CT, although collecting system content density may be helpful [18,19]; notably, recent contrast administration can also affect this density. 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 Hydronephrosis on Prior Imaging-Unknown Cause patients, they advised a low-dose CT scan if the size and location of the stone is desired to plan surgical management. CT Abdomen With IV Contrast There is limited evidence to support the use of CT abdomen with IV contrast (separate from CTU) for initial imaging of patients with symptomatic hydronephrosis with unknown cause. CT Abdomen Without and With IV Contrast There is limited evidence to support the use of CT abdomen without and with IV contrast (separate from CTU) for initial imaging of patients with symptomatic hydronephrosis with unknown cause. CT Abdomen Without IV Contrast There is limited evidence to support the use of CT abdomen without IV contrast (separate from CTU) for initial imaging of patients with symptomatic hydronephrosis with unknown cause.
Hydronephrosis on Prior Imaging Unknown Cause. CT can be useful in patients with renal colic and moderate to severe hydronephrosis by US, because these patients can be at higher risk of stone passage failure [16], although some authors suggest CT should be reserved in renal colic patients for when US is nondiagnostic or when an alternative diagnosis is suspected [17]. In cases of suspected infection, it can be difficult to distinguish pyonephrosis from hydronephrosis even by CT, although collecting system content density may be helpful [18,19]; notably, recent contrast administration can also affect this density. 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 Hydronephrosis on Prior Imaging-Unknown Cause patients, they advised a low-dose CT scan if the size and location of the stone is desired to plan surgical management. CT Abdomen With IV Contrast There is limited evidence to support the use of CT abdomen with IV contrast (separate from CTU) for initial imaging of patients with symptomatic hydronephrosis with unknown cause. CT Abdomen Without and With IV Contrast There is limited evidence to support the use of CT abdomen without and with IV contrast (separate from CTU) for initial imaging of patients with symptomatic hydronephrosis with unknown cause. CT Abdomen Without IV Contrast There is limited evidence to support the use of CT abdomen without IV contrast (separate from CTU) for initial imaging of patients with symptomatic hydronephrosis with unknown cause.