Detection of obstructive uropathy by bone scintigraphy

We prospectively evaluated routine bone scintigraphs to determine the prevalence of radiotracer retention in the renal collecting system, and to test the reliability of this finding as an indicator of obstructive uropathy. Post-diuretic renal washout was also measured, to evaluate the use of this procedure after bone scintigraphy. Stasis occurring only in the supine position was excluded by obtaining upright images. The findings on bone scintigraphy were compared with the results of renal sonography. Patients showing persistent pelvicaliceal concentration in the upright position after bone scintigraphy were found to have evidence of obstructive uropathy by sonography or other studies. Furosemide administration was followed by washout of the bone tracer from all kidneys with proven partial ureteral obstruction. Persistent renal pelvicaliceal concentration, in upright images after bone scintigraphy, appears to be a reliable indicator of obstructive uropathy. However, measurement of post-diuretic renal washout, after bone scintigraphy, does not reliably detect obstructive uropathy, and may be misleading if interpreted in the same way as the standard diuretic renogram.