Notably, most of the included patients were children <2 years of age, and the MRU technique used included a diuretic component. In a prospective study of 13 people without and 15 people with hydronephrosis, Wang et al [13] reported significant correlation between MRU and DRG estimations of single-kidney GFR and that MRU is comparable to DRG for estimation of GFR in the setting of hydronephrosis. They note that both MRU and DRG may somewhat overestimate global GFR in the setting of obstructive hydronephrosis. MRU Without IV Contrast Although there is limited evidence to support the use of MRU without IV contrast for initial imaging of patients with asymptomatic unilateral hydronephrosis with unknown cause, MRU without IV contrast is, in general, preferred over CTU in patients with renal impairment [15]. MRU without IV contrast is useful for investigating the etiology of hydronephrosis and can be combined with anatomical imaging to provide more information than anatomical imaging alone but does not provide the level of functional imaging attainable with MRU without and with IV contrast. Radiography Abdomen and Pelvis There is limited evidence to support the use of radiography of the abdomen and pelvis for initial imaging of patients with asymptomatic unilateral hydronephrosis with unknown cause. Radiography of the abdomen and pelvis is not useful in this setting, and CT is more sensitive for obstructive urolithiasis. Radiography Intravenous Urography There is limited evidence to support the use of radiography with IV urography (IVU) (also referred to as IV pyelogram [IVP]) for initial imaging of patients with asymptomatic unilateral hydronephrosis with unknown cause. US Abdomen There is relatively limited evidence to support the use of US of the abdomen for initial imaging of patients with asymptomatic unilateral hydronephrosis with unknown cause.
Hydronephrosis on Prior Imaging Unknown Cause. Notably, most of the included patients were children <2 years of age, and the MRU technique used included a diuretic component. In a prospective study of 13 people without and 15 people with hydronephrosis, Wang et al [13] reported significant correlation between MRU and DRG estimations of single-kidney GFR and that MRU is comparable to DRG for estimation of GFR in the setting of hydronephrosis. They note that both MRU and DRG may somewhat overestimate global GFR in the setting of obstructive hydronephrosis. MRU Without IV Contrast Although there is limited evidence to support the use of MRU without IV contrast for initial imaging of patients with asymptomatic unilateral hydronephrosis with unknown cause, MRU without IV contrast is, in general, preferred over CTU in patients with renal impairment [15]. MRU without IV contrast is useful for investigating the etiology of hydronephrosis and can be combined with anatomical imaging to provide more information than anatomical imaging alone but does not provide the level of functional imaging attainable with MRU without and with IV contrast. Radiography Abdomen and Pelvis There is limited evidence to support the use of radiography of the abdomen and pelvis for initial imaging of patients with asymptomatic unilateral hydronephrosis with unknown cause. Radiography of the abdomen and pelvis is not useful in this setting, and CT is more sensitive for obstructive urolithiasis. Radiography Intravenous Urography There is limited evidence to support the use of radiography with IV urography (IVU) (also referred to as IV pyelogram [IVP]) for initial imaging of patients with asymptomatic unilateral hydronephrosis with unknown cause. US Abdomen There is relatively limited evidence to support the use of US of the abdomen for initial imaging of patients with asymptomatic unilateral hydronephrosis with unknown cause.