Lower Urinary Tract Reconstruction for Duplicated Obstructive Systems: Is Preoperative Renal Scan Necessary?
Devon C. Snow-Lisy, MD1, Grace Yoshiba, BS2, Edward C. Diaz, MD3, Max Maizels, MD1, Elizabeth B. Yerkes, MD1, Bruce W. Lindgren, MD1, Edward M. Gong, MD1, Dennis B. Liu, MD1, Earl Y. Cheng, MD1.
1Ann and Robert H. Lurie Children's Hospital of Chicago, Chicago, IL, USA, 2University of Illinois College of Medicine at Peoria, Peoria, IL, USA, 3Stanford University Medical Center, Palo Alto, CA, USA.
BACKGROUND: Need for functional assessment of duplicated obstructive systems prior to surgical correction remains controversial. Proponents of an upper tract approach, i.e. hemi-nephrectomy, recommend testing prior to removal of the segment in order to ensure poor function. At our institution, regardless of function, we prefer a lower tract reconstruction (LTR), i.e. uretero-ureterostomy or ureteral reimplant, due to previously reported low reoperation rates and good short-term outcomes. The purpose of the study was to assess preoperative renal scan utility as well as extended outcomes of primary LTR in those with a duplicated obstructed kidney due to ureterocele or ectopic ureter.
METHODS: An IRB approved, retrospective review identified 118 patients who underwent LTR for obstructed duplex kidneys from 1991-2014. Obstructive duplication was defined as surgically confirmed duplication with hydronephrosis not attributed to vesicoureteral reflux, regardless of functional testing. Patients with comorbidities potentially affecting bladder function including primary bladder neck insufficiency, anorectal malformation, and neurogenic bladder were excluded. Fisher’s exact test was used for categorical comparative analysis (JMP v.11).
RESULTS: Renal scans were obtained preoperatively in 70% (83/118, DMSA 9%, MAG3 62%) and showed non-function in 12%, poor function in 72% and retained function in 16%. The etiology of the obstruction was ureterocele in 47% (55/118) and ectopic ureter in 53% (63/118) (Figure 1). Neither rates of obtaining a renal scan nor the functional results were significantly different between ureterocele and ectopic ureter cases (p=ns). With a median post-op follow-up of 1.8 years (IQR 0.7-4.2), neither the use of renal scan, the function of the affected moiety, nor the underlying etiology of obstruction impacted improvement in hydronephrosis, need for secondary procedures, or development of hypertension/proteinuria (p=ns). LTR was effective with similar to improved hydronephrosis in all cases. Two patients (1.7%) required secondary procedures, both of whom had poor function on renal scan preoperatively. One patient underwent endoscopic incision of residual ureterocele for infections and incontinence. The other patient had residual reflux and infections. She underwent deflux twice followed by a robotic upper pole heminephrectomy due to family preference for removal of the affected moiety. No patient required anti-hypertensives, had clinically significant proteinuria, or required removal of the dysplastic moiety due to development of hypertension or proteinuria.
CONCLUSIONS: Preoperative renal scan did not predict improvement of hydronephrosis, need for secondary procedures, or incidence of hypertension and proteinuria after primary LTR for patients with obstructed duplicated systems secondary to either ureterocele or ectopic ureter. LTR is efficacious and associated with a low rate of secondary procedures (1.7%). We found no evidence of any significant complications associated with leaving a dysplastic renal moiety in situ. Primary LTR continues to be our preferred approach for the vast majority of patients with obstructed duplex kidneys regardless of function, obviating the need for preoperative renal scan. 
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