Additionally, US color Doppler kidneys and bladder retroperitoneal allows evaluation of ureteral jets, bladder distension, and postvoid residual bladder volume and can allow measurement of the prostate to evaluate for prostatomegaly. Unilateral elevation of resistive indices is nonspecific but can be seen in the setting of obstruction. However, more comprehensive evaluation can often be achieved with CT, MRU, or renal scintigraphy. Hydronephrosis on Prior Imaging-Unknown Cause If the degree of hydronephrosis is unknown in a patient with hydronephrosis and renal colic, US may be useful to determine degree of hydronephrosis and therefore the likelihood of symptomatic renal stone [36]. Multiple reports indicate the diagnosis of obstructing stone can be made without further imaging after identification of hydronephrosis [37] or urolithiasis [33] in patients with renal colic. A meta-analysis by Wong et al [36] found that in patients with renal colic, moderate or greater hydronephrosis on POCUS was highly specific (94.4%) for presence of symptomatic renal stone, although they noted that severe hydronephrosis is rare and should prompt consideration of alternate causes. Similarly, Taylor et al [38] found in a study of 483 patients that US finding of either at least stones or moderate to severe hydronephrosis was 97% sensitive and 28.1% specific in predicting need for urologic intervention, noting that all 3 cases with severe hydronephrosis underwent intervention. An additional study evaluating 384 patients with unilateral flank pain found that the degree of hydronephrosis was strongly correlated with the number of calculi but weakly correlated with the size of the calculus [39].
Hydronephrosis on Prior Imaging Unknown Cause. Additionally, US color Doppler kidneys and bladder retroperitoneal allows evaluation of ureteral jets, bladder distension, and postvoid residual bladder volume and can allow measurement of the prostate to evaluate for prostatomegaly. Unilateral elevation of resistive indices is nonspecific but can be seen in the setting of obstruction. However, more comprehensive evaluation can often be achieved with CT, MRU, or renal scintigraphy. Hydronephrosis on Prior Imaging-Unknown Cause If the degree of hydronephrosis is unknown in a patient with hydronephrosis and renal colic, US may be useful to determine degree of hydronephrosis and therefore the likelihood of symptomatic renal stone [36]. Multiple reports indicate the diagnosis of obstructing stone can be made without further imaging after identification of hydronephrosis [37] or urolithiasis [33] in patients with renal colic. A meta-analysis by Wong et al [36] found that in patients with renal colic, moderate or greater hydronephrosis on POCUS was highly specific (94.4%) for presence of symptomatic renal stone, although they noted that severe hydronephrosis is rare and should prompt consideration of alternate causes. Similarly, Taylor et al [38] found in a study of 483 patients that US finding of either at least stones or moderate to severe hydronephrosis was 97% sensitive and 28.1% specific in predicting need for urologic intervention, noting that all 3 cases with severe hydronephrosis underwent intervention. An additional study evaluating 384 patients with unilateral flank pain found that the degree of hydronephrosis was strongly correlated with the number of calculi but weakly correlated with the size of the calculus [39].