The success rate of open pyeloplasty reported in the published pediatric literature is well in excess of 95% (
5). The original description of dismembered pyeloplasty advocates for non-stented repair, but as techniques have improved and as more postoperative complications were reported, drainage with stents and nephrostomy tubes have been used more liberally. However, postoperative drainage has not been uniformly reported in many published articles ( 6). Some authors have recommended a nephrostomy tube either with or without a stent to divert the urine and to keep the anastomosis dry ( 1). There is general agreement that the upper urinary tract should be drained after pyeloplasty in high-risk patients, such as those with poor renal function, extreme pyelocaliectasis, a single kidney, an inflamed renal pelvis, or a revision pyeloplasty ( 7). Different types of externalized and/or internal stents have been described ( 8). In addition, perinephric drains and urinary bladder catheters are used in a considerable number of cases.
The three most common reasons to use a stent and a nephrostomy tube are to ensure urinary diversion, to retain the ureteral caliber, and to maintain anastomotic patency and alignment. The main objective of draining the pelvis after pyeloplasty is to prevent urine leakage through the anastomosis. In addition, postoperative edema and undesirable kinking at the anastomosis site may cause ureteral occlusion that could lead to immediate and prolonged complications and hospitalization. These complications are worrisome to the surgeon as well as to parents (
1, 9); stenting prevents these complications.
As reported in the literature, urologic complications may occur in both stented and non-stented patients, although they are slightly more frequent in non-stented groups (14% vs. 12%, respectively) (
4, 10- 12).
The NU catheter used in this study allows for maximal drainage of the pelvis, preventing any hydronephrosis secondary to edema of the anastomosis and also any early trans-anastomotic leakage and subsequent peri-anastomotic scarring. This NU catheter also provides for better alignment of the renal pelvis and ureter and facilitates external access to visualize the reconstructed area radiologically. This catheter remains in the renal collecting system for only 12 days postoperatively, whereas according to the published literature, routine operations involve a combination of devices, including a nephrostomy tube and a double pigtail ureteral stent, while a Penrose drain Foley catheter is used as a protective mechanism for 14 days, 2 - 6 weeks, 7 - 10 days, and 24 - 48 hours, respectively (
DJ stenting may be difficult or impossible in infants because of the small size of the UVJ (
14). In contrast, the NU catheter diverts the upper tract only and does not cross the UVJ.
The only notable complication in our series was the occurrence of UTI in 15 of our 142 patients (148 pyeloplasties). In our opinion, the signs and symptoms of UTI and transient obstructive symptoms after removal of the stent may indicate anastomotic edema and malfunction, which can take several weeks to resolve, or as a complication of a foreign body (NU catheter) in the urinary tract (debris). We believe that the existence of debris in the stented urinary tract and its associated transient obstructive effects in the ureter may play a role in this complication. In most of these cases, we found that the urine samples obtained through the external catheter before its removal usually contained a number of white blood cells, red blood cells, and bacteria. Although the fever and positive urine culture seen in patients with DJ can be due to reflux (
14), we have been unable to determine why some patients develop UTIs after catheter removal while others do not. More work is needed in this area to prevent UTIs and identify their causes.
Two of the most important concerns of an externalized drainage tube are its poor functioning and dislodgement before its intended removal. When this technique was implemented in our clinical trial, we did not observe any premature dislodgment or unintentional removal. As previously mentioned, this catheter was the sole method of drainage in our patients. We emphasize proper placement and securing of the catheter intraoperatively with the aim of keeping it in a fixed position within the renal pelvis for the desired length of time.
Many reports in the literature indicate that external drainage techniques are unequivocally associated with longer hospital stays. In our study, all patients were discharged 48 hours postoperatively. However, in a comparative study, although there was a longer stay for patients with a nephrostomy tube, it had lower overall costs (
14). The 48-hour hospital stay was intended to provide acute care management, primarily due to the need for intravenous hydration, antibiotic therapy, parenteral pain control, flushing of the catheter to prevent blockage, and educating parents in caring for the external drainage catheter.
Another problem is the inconvenience of having an external drainage device for the child and his or her parents. Of course, the problem is varied in different cultural and social environments. In the opinion of some authors with whom we have had personal communication, performing a contrast study through the tube that crosses the UPJ is not very useful in demonstrating leaks in the suture line, nor does it demonstrate patency of the anastomosis that is being stented by the tube. However, this procedure can actually show distal patency.
One other drawback to an externalized ureteral stent as reported in the literature is the increased risk of UTI (as seen in 15 of our patients), a prolonged hospital stay, and restricted mobility of the patient postoperatively (
12). The creation of local ischemia, pressure necrosis, and subsequent stricture formation, particularly in the small caliber ureters, has also been attributed to the presence of a ureteral stent ( 12). We did not experience these complications in any of our patients.
One clear and main limitation of this study is the lack of a comparative control group. Although a historical control group is not sufficient, in the past we would have applied some additional measures to better ensure appropriate drainage, including a nephrostomy tube in addition to the ureteral stent, perinephric drains, and a Foley catheter. With experience, we decided that a single NU 5-Fr catheter as the sole method of drainage without any additional catheter or drain usually addresses the required protection for pyeloplasty. Therefore, we set up this descriptive case series using only a NU 5-Fr catheter for the pyeloplasty.
This method has not been widely used and also carries the message that in children, a single 5-Fr catheter is sufficient for the prevention of postoperative leakage. There is no fear of dislodgement and migration or mechanical irritation of the bladder trigone, which are often seen with DJ catheters. While these conditions might also occur with NU catheters that have been used for quite some time, they are often associated with the concurrent use of some other protective measures, such as a Foley catheter or perinephric drain.
In pediatric pyeloplasty for the correction of congenital UPJO, radiologic exploration of the distal ureter is critical. Many centers employ preoperative cystoscopy and retrograde ureterography. In our patients, we performed this task with antegrade contrast study through the catheter and found five cases of UVJO. We treated this second anomaly individually.
The use of a percutaneous externalized 5-Fr NU (feeding tube) with multiple side holes as the sole instrument for diversion after open pyeloplasty was sufficient to prevent anastomotic leakage. Patent anastomosis was achieved in 98.7% of the cases according to long-term follow-up, and there were only a few notable complications. The catheter was well tolerated and offered the combined advantages of a nephrostomy tube and an internal stent and also allowed for radiologic study of the anastomosis and the distal ureter while obviating the need for a second anesthetic for its removal. Therefore, it can be a good option during pyeloplasty, especially in developing countries with low economies and poor medical facilities.
Further research is required to identify ways to prevent the risk of symptomatic UTI associated with an externalized NU catheter after its removal.