Detection of ureteral obstruction on radionuclide bone scans.

The kidneys are nearly always visible on a routine radionuclide bone scan. To assess the reliability of the bone scan in detecting ureteral obstruction, 220 bone scans and excretory urograms were compared in 53 patients followed serially for prostatic cancer. There were 15 kidneys obstructed on excretory urograms. Only nine were diagnosed as obstructed on the bone scans. Seven of the nine cases of unilaterally obstructed kidneys were detected, whereas only two of the six kidneys in three patients with bilateral obstruction were correctly diagnosed. The results indicate that unilateral obstruction is more likely to be detected, whereas bilateral obstruction is more likely to be missed, on bone scans. Therefore, the routine radionuclide bone scan is an unreliable test for ureteral obstruction.