How is hydronephrosis without obstruction or with asymptomatic obstruction evaluated?

Updated: Dec 16, 2020
  • Author: Dennis G Lusaya, MD; Chief Editor: Bradley Fields Schwartz, DO, FACS  more...
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In some cases, one of the above radiologic tests demonstrates hydronephrosis without evidence of obstruction. This is a normal finding in pregnant women. Megaureter due to previous marked vesicoureteral reflux or a dilated but nonobstructed extrarenal pelvis is the most common example of this problem. These patients are often being evaluated for back or flank pain, and the following two questions need to be answered:

  • Is obstruction present?
  • Is the obstruction responsible for the pain?

In this setting, 3 different tests have been used: diuretic renography, IVP (less often), and perfusion pressure flow studies. [2]

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