Is routine renography required after pyeloplasty?

Purpose: We assessed whether renography should be performed routinely following pyeloplasty.

Materials And Methods: We identified the records of all patients undergoing pyeloplasty at our hospital between 1989 and 2005. Patients were eligible for the study if they had undergone preoperative ultrasound and renal scan, and postoperative ultrasound and renal scan within 3 months and 1 year postoperatively, respectively. Patients were excluded if they had associated anomalies or high grade reflux. Postoperative downgrading or decompression of the pelvicaliceal dilatation within the same grade was recorded as "improved," while unchanged or worsening hydronephrosis was recorded as "no improvement." All information was obtained from the official radiologist reports rather than from the postoperative surgeon notes. Data obtained from the postoperative renal scan included the presence or absence of obstruction as well as split renal function. We compared postoperative ultrasound and renal scan, as well as changes between preoperative and postoperative split renal function in patients with a normal contralateral kidney. Fisher's exact test was used for comparison.

Results: A total of 97 patients who underwent 101 pyeloplasties at a median age of 18 months were eligible for review. Mean +/- SD followup was 4.5 +/- 2 years. Of the 91 kidneys with improvement on postoperative ultrasound 2 (2%) had an obstructive postoperative renal scan, which spontaneously resolved during followup. In contrast, of the 10 kidneys with postoperative ultrasound showing no improvement 4 (40%) had an obstructive renal scan, of which 2 (50%) required a second procedure (p <0.001). Of the 46 kidneys with downgraded hydronephrosis none had an obstructive postoperative renal scan, compared to 6 of 55 (11%) without downgrading (p <0.03). Of the 49 patients with preoperative split renal function greater than 45% none demonstrated changes of more than 5% postoperatively, compared to 15 of 35 (43%) with split renal function less than 45% (p <0.001).

Conclusions: Patients in whom postoperative ultrasound reveals downgrading may not require postoperative renal scan to rule out obstruction. However, those with preoperative function less than 45% may exhibit functional changes greater than 5% that can be determined by postoperative renal scan.