In the present study, we found that the symptomatic ureteric stump syndrome rate after upper tract approach treatment was 7.9% and that risk factors for symptomatic ureteric stump syndrome was the length of residual ureteral stump. Ureteric stump syndrome in children who underwent upper tract approach treatment occurred < 4.5 months after surgery, careful follow-up is necessary at least for 12 months for ureteric stump syndrome after surgery, and administration of antibiotic drugs is a sensible measure in conservative management of ureteric stump syndrome.
The underlying anatomical and functional divisions of the upper and lower moieties of the duplicated system are highly complex. Obstruction of the upper moiety leads to loss of function or reflux into the lower moiety [7]. Patients with duplex systems may present with antenatally detected hydronephrosis, continuous urinary incontinence, flank pain or recurrent UTIs that increase the risk of renal scarring and compromised renal function [6].
Currently, duplex collecting systems with ureterocele or ectopic ureter in pediatric patients is treated by heminephrectomy or ureteroureterostomy [8]. Upper tract approaches do not damage the bladder and can be performed in young infants before trigonal maturation. However, retention of a distal ureteral stump is still a concern since it can be a potential source of infection or abscess, and often necessitates surgical resection, especially when the ureteral stump is refluxing or severely dilated [9]. Nevertheless, subtotal ureterectomy appeared to be safe and feasible approach in patients with duplex kidney and poorly functioning pole moiety where residual ureteric stump is left intact, and patients may still benefit without further surgical intervention [10; 11].Heminephrectomy with subtotal ureterectomy has been the traditional surgical management of children with poorly functioning affected pole moieties in duplex renal collecting systems having ureteral ectopia and ureterocele, and heminephrectomy can lead to risk of de novo or persistent VUR and injury to the non-affected pole moiety [12; 13].
Recommendation for heminephrectomy of ureteral duplication with ureterocele and uretral ectopia, there is documentation about the natural history of the remnant residual ureteral stump. Androulakakis et al reviewed the outcome of 41 patients with obstructive ectopic ureterocele and poorly functioning upper moiety who underwent heminephrectomy, and found that during the 9-year follow-up, only one patient required a secondary procedure to remove the symptomatic distal ureteric stump due to recurrent hematuria and bacteriuria [12]. De Caluwe et al assessed the long-term outcome of lower pole heminephrectomy in 19 children with duplex kidneys and non-functioning lower pole moieties, of which most patients had massive reflux nephropathy, during the mean follow-up period of 102 months, only 8 patients experienced episodes of UTIs and reflux into the retained ureteral stump[13]. There were no major complications related with the ureteral stump except in 2 patients, who required stump resection due to febrile UTIs. In our cohort, 11 of 203 patients who underwent upper tract surgery required secondary operation due to the development of UTIs at the residual ureteral stump.
With no identifiable negative effect on hypertension and tumorigenesis leaving poorly functioning renal tissue left in situ [14], ureteroureterostomy carries the advantage of low risk of morbidity while preserving even minimal pole moiety function, and is increasingly being considered as a safer upper tract surgical intervention for duplicated systems that can potentially leave residual ureteral stump[15]. There are reports indicating that most patients with residual ureteric stump after ureteroureterostomy do not require stump resection, and there are few adverse consequences of preserving poorly functioning renal moieties. Bockrath et al reported that the short residual ureteral stump did not lead to complications after ipsilateral ureteroureterostomy in children with the duplex system [15]. Kawal et al performed ipsilateral ureteroureterostomy in 53 cases of ectopia or ureterocele affecting the upper pole in duplex system, and observed few ureteral stumps in all cases that did not require secondary surgery [16]. In our cohort as well, no patient experienced UTIs at residual ureteral stump and underwent a secondary resection after ureteroureterostomy.
Preoperative VUR into the moiety pole ureter is not risk factor of ureteric stump syndrome. De Caluwe et reviewed the follow-up results of 50 patients of mean age 6 years with distal ureteral stumps following heminephrectomy and partial ureterectomy, and found that only 5 patients had ureteric stump infections that required removal of the ureteral stump, thereby concluding that refluxing ureteral stump had low morbidity [10]. In our study, 2 of the 27 patients with preoperative VUR into the moiety pole ureter had the distal ureteral stump infection, and the number of patients with VUR into the upper pole ureter was too small to be significant. However, since postoperative VCUG was not performed after upper tract treatment unless clinically indicated, the total number of patients with postoperative VUR into the upper pole ureter cannot be gauged accurately.
A long stump is a potential risk factor of ureteric stump syndrome [17]. Jelloul and Valayer found that the short distal ureteral stump did not result in complications after ipsilateral ureteroureterostomy to treat VUR or obstruction in children with the duplex system [18]. We also observed a correlation between the ureteral stump length and increased risk of ureteric stump infections after upper tract approach, and reach statistical significance. Furthermore, Lee et al found that 9 out 74 patients with ectopic ureters had to undergo ureteral stump resection over a follow-up period of 5 years after ureteroureterostomy due to UTIs. In addition, the preoperative upper pole ureter diameter was correlated with the development of UTIs at the residual ureteral stump [11], which was not consistent with our findings as well.
Only recently, studies have shown patients with ureteral duplication associated with ureteroceles or ectopic ureters, irrespective of the degree of ureteral dilation or preoperative renal function are at a low risk of ureteric stump syndrome. Harms et al published study has explicitly compared patients with a large sized affected ureter to small sized and find that the size of the affected ureter does not impact postoperative outcome including residual stump related complications [15]. Previous studies demonstrate that the affected pole moiety function has no bearing on the surgical outcome in children with ectopia or ureterocele duplex collecting systems [19; 20]. In our analysis, we demonstrated similar findings affected ureter dilation and pole moiety function were not correlated with the development of a urinary tract infection at the residual ureteral stump.
The frequency of ureteric stump syndrome in our cohort was similar to that previously reported. However, there are potential limitations of our study due to its retrospective nature. Since the treatment was selected based on the surgeon’s preference and patient anatomy rather than randomized study, there is a potential of selection bias. In addition, preoperative VUR in proportions of patients was not known. Therefore, a larger cohort would further elucidate a possible correlation between preoperative VUR and ureteric stump syndrome.