Suspected obstructive pyelocaliectasis: Doppler ultrasonography compared with diuretic renal scintigraphy in proven cases

Objective: To compare Doppler ultrasonography with diuretic renal scintigraphy in the differentiation of obstructive from nonobstructive pyelocaliectasis. Patients and Method: The authors reviewed the findings of Doppler ultrasonography and diuretic renal scintigraphy performed over a 3-year period for 27 pyelocaliectatic kidneys (17 obstructed and 10 unobstructed) in 20 individuals ranging in age from 19 to 88 years. The kidneys were classified as 'obstructed' or 'unobstructed' on the basis of the resistive index as calculated from Doppler ultrasonographic results and as 'obstructed', 'unobstructed' or 'indeterminate' on the basis of the clearance half-time determined from scintigraphic findings. RESULTS: On the basis of scintigraphy, the obstruction status was indeterminate in 12 of the 27 kidneys. The data were analysed for sensitivity and specificity in two ways, first by classifying the kidneys with indeterminate obstruction status as 'obstructed,' and then by excluding them from the analysis altogether. In both situations, the differences in sensitivity and specificity between Doppler ultrasonography and scintigraphy were not statistically significant (χ² test, p > 0.05). When the kidneys with indeterminate obstruction status were included in the obstructed category, the sensitivity and specificity of Doppler ultrasonography were 94% and 90% respectively and of scintigraphy 100% and 70% respectively; when the kidneys with indeterminate obstruction status were excluded, the sensitivity and specificity of Doppler ultrasonography were 83% and 89% respectively and of scintigraphy 100% and 78% respectively. Conclusions: These results suggest that Doppler ultrasonography is comparable to diuretic renal scintigraphy in the work-up of potential obstructive pyelocaliectasis. Because grey-scale ultrasonography is usually performed before scintigraphy, a Doppler examination could be added at this stage, which might reduce the time necessary to establish the diagnosis.