Is One Early Renographic Follow-Up Adequate to Measure the Success of Robotic Pyeloplasty?

PURPOSE: Diuretic renography (DRG) is commonly used to diagnose ureteropelvic junction obstruction (UPJO) and to evaluate the success of surgical repair (pyeloplasty). Duration, frequency, and interpretation of renographic follow-ups are still under dispute.

METHODS: We retrospectively reviewed 94 consecutive patients diagnosed with UPJO who underwent a minimally invasive, robotically assisted laparoscopic pyeloplasty at our institution between January 2009 and September 2015. DRG was carried out preoperatively and again routinely 4 to 6 weeks postoperatively the day after stent removal (early DRG). Patients were scheduled for repeat (late) DRG and follow-up examinations, including clinical status and ultrasonography.

RESULTS: Nineteen patients with missing preoperative DRG were excluded from the study; the remaining 75 patients were eligible for statistical evaluation. At follow-up, 98.7% reported no or only very mild and rare symptoms. On early DRG, 52.5% had T1/2  ≤ 10 min (unobstructed), 39.3% had T1/2 between 10 and 20 minutes (equivocal), and 8.2% had T1/2  ≤ 20 minutes (obstructed). At late follow-up, the DRG results had improved to 80.8% unobstructed with 19.2% remaining equivocal, and no patients were obstructed; thus, the overall success rate was 80.8%. There was only one patient who worsened from unobstructed to equivocal from early to late DRG assessment.

CONCLUSION: In case of complete symptom resolution, a nonobstructive diuretic half-time of ≤10 minutes on early DRG following stent removal suggests that further routine renographic follow-up is unnecessary. Patients with an equivocal early DRG (T1/2 between 10 and 20 minutes) require further scintigraphic follow-up, as they have a 42.1% chance of staying equivocal.