CTU Without and With IV Contrast Although there is relatively limited evidence to support the use of CTU without and with IV contrast for initial imaging of patients with symptomatic hydronephrosis with unknown cause, CTU is useful for investigating the etiology of hydronephrosis. CTU provides a near-comprehensive evaluation of the genitourinary tract including both morphological and functional information. In a prospective study evaluating 70 patients with renal colic or hematuria, CTU was performed after hydronephrosis was confirmed with US and was able to detect 100% of renal calculi but was less sensitive in detection of other causes of obstruction [28]. DTPA Renal Scan DRG is the de facto standard of care in diagnosis of renal obstruction [10] and can be used to determine whether obstructive uropathy is truly present in cases of incidentally noted hydronephrosis [11]. However, tubular tracers (eg, MAG3 and 123I) are much more efficiently extracted by the kidney than DTPA, and washout is therefore easier to evaluate with tubular tracers. Use of DTPA for diuretic renography may result in an equivocal or false-positive diuretic study compared with MAG3, particularly in patients with reduced function, and is not favored for imaging only studies [11,12]. DRG with DTPA is useful for estimating single-kidney GFR, although it may somewhat overestimate global GFR in the setting of obstructive hydronephrosis [13]. Fluoroscopy Antegrade Pyelography There is limited evidence to support the use of fluoroscopic antegrade pyelography for initial imaging of patients with symptomatic hydronephrosis with unknown cause. Fluoroscopy Voiding Cystourethrography There is limited evidence to support the use of fluoroscopic voiding cystourethrography for initial imaging of patients with symptomatic hydronephrosis with unknown cause.
Hydronephrosis on Prior Imaging Unknown Cause. CTU Without and With IV Contrast Although there is relatively limited evidence to support the use of CTU without and with IV contrast for initial imaging of patients with symptomatic hydronephrosis with unknown cause, CTU is useful for investigating the etiology of hydronephrosis. CTU provides a near-comprehensive evaluation of the genitourinary tract including both morphological and functional information. In a prospective study evaluating 70 patients with renal colic or hematuria, CTU was performed after hydronephrosis was confirmed with US and was able to detect 100% of renal calculi but was less sensitive in detection of other causes of obstruction [28]. DTPA Renal Scan DRG is the de facto standard of care in diagnosis of renal obstruction [10] and can be used to determine whether obstructive uropathy is truly present in cases of incidentally noted hydronephrosis [11]. However, tubular tracers (eg, MAG3 and 123I) are much more efficiently extracted by the kidney than DTPA, and washout is therefore easier to evaluate with tubular tracers. Use of DTPA for diuretic renography may result in an equivocal or false-positive diuretic study compared with MAG3, particularly in patients with reduced function, and is not favored for imaging only studies [11,12]. DRG with DTPA is useful for estimating single-kidney GFR, although it may somewhat overestimate global GFR in the setting of obstructive hydronephrosis [13]. Fluoroscopy Antegrade Pyelography There is limited evidence to support the use of fluoroscopic antegrade pyelography for initial imaging of patients with symptomatic hydronephrosis with unknown cause. Fluoroscopy Voiding Cystourethrography There is limited evidence to support the use of fluoroscopic voiding cystourethrography for initial imaging of patients with symptomatic hydronephrosis with unknown cause.