What is the role of diuretic renography in the workup of hydronephrosis and hydroureter?

Updated: Dec 16, 2020
  • Author: Dennis G Lusaya, MD; Chief Editor: Bradley Fields Schwartz, DO, FACS  more...
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Diuretic renography involves the administration of a loop diuretic (eg, 0.5 mg/kg of furosemide) prior to radionuclide renal scanning or during IVP, while the latter involves percutaneous insertion of a catheter into the dilated renal pelvis, followed by fluid perfusion into the pelvis at a rate of 10 mL/min. The marked increase in urine flow should, if obstruction is present, slow the rate of washout of the radioisotope during renal scanning, further increase the size of the collecting system on IVP, or elevate the renal pelvic pressure to above 22 mm Hg during a perfusion study. Furthermore, any of these procedures may precipitate pain similar to the patient's initial complaint.

Noninvasive diuretic renography is generally preferred. However, optimal interpretation of any of these test results is uncertain, because both false-positive and false-negative results may be seen. Nevertheless, the following general recommendations have been made:

  • Surgical correction should be considered in a patient with pain and positive diuretic renography findings.

  • No therapy is necessary in an asymptomatic patient with positive diuretic renography findings but normal renal function. These patients often are adults and have therefore had the partial obstruction for many years without apparent damage to the kidney. Hydronephrosis may first be noted after a radiologic study is performed for some other reason, or, as noted above, obstruction may be suspected when pain is induced after a period of high fluid intake leads to a diuresis that exceeds the rate at which urine can flow through the obstructed area. Similarly, the decreased washout observed on renography occurs only at a urine flow rate much higher than the patient is likely to achieve on his or her own. Periodic monitoring of renal function and renal parenchymal size (by ultrasonography) is indicated in these patients to exclude progressive renal injury.

  • No therapy is indicated in an asymptomatic patient with negative renography findings. Long-term follow-up has demonstrated stable renal function in most of these patients.

  • A perfusion pressure flow study should be performed in a symptomatic patient with negative or equivocal diuretic renography findings. Some nonrenal cause for the pain is probably present if the perfusion study is negative. On the other hand, a positive study is suggestive of obstruction and the need for surgical correction.

  • A perfusion pressure flow study may also be performed in patients with hydronephrosis and poor renal function. The diuretic renogram may be falsely negative in this setting, because the diuretic may not sufficiently raise the urine flow.

In general, approximately 50% of patients with positive diuretic renography findings eventually require surgery, either for pain or progressive parenchymal loss. [16]

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