A 1-week-old boy with a prenatal history of left hydroureteronephrosis (HUN) involving the lower pole moiety of a duplex system is seen for evaluation.
Postnatally, the findings of left HUN involving the lower pole moiety were confirmed on renal/bladder ultrasound (Figures 1 and 2). The left lower pole moiety showed thin echogenic parenchyma with little to no flow on Color Doppler imaging. A voiding cystourethrogram (VCUG) demonstrated Grade 4-5 vesicoureteral reflux (VUR) (Figure 3). Amoxicillin preventative was administered. The technetium-99m dimercaptosuccinic acid scan (DMSA) scan at 2 months showed <15% function of the lower pole moiety (Figure 4). The left upper pole and right kidney functioned normally.
Because there was minimal function of the left lower pole moiety, a left lower pole nephroureterectomy with ligation of the distal-most ureter was recommended but the parents did not want extirpative renal surgery. Therefore, a left lower to upper pole ipsilateral ureteroureterostomy (IUU) was suggested as an alternative management strategy. The patient underwent cystoscopy and placement of a 4 Fr ureteral stent into the lower pole ureter to aide identification intraoperatively.
The position was confirmed with retrograde pyelography. The stent was brought through the silicone end of an 8 Fr Foley catheter (via a 16 Fr angiocatheter) to drain into the Foley catheter bag. The patient was repositioned into supine, and a left IUU was performed via an inguinal incision. The ureters were identified ~3 to 4 cm from the bladder wall and separated proximal to the area of shared blood supply. Once the stent was palpated in the lower pole ureter, it was removed from below.
A 2-cm ureteroureterostomy was performed using 6-0 polydioxanone suture with all knots tied outside the ureteral lumen. A 12 blade (hawk-bill) was used to aide in the incision of the normal ureter. A Penrose drain was placed lateral to the anastomosis. A gauze sponge was placed over the drain with only with a single piece of tape (non-occlusive) and changed at the time of diaper changes. The Penrose was removed only after the gauze sponges were dry for 48 hours.
A renal sonogram at 3 weeks showed mild dilation of the upper and severe hydronephrosis of the lower pole moieties (Figure 5). Decompression of the systems was seen at 4 months postoperatively (Figure 6).
Classically, persistent high-grade VUR in a non-functioning or poorly functioning lower pole moiety has been managed with lower pole nephrectomy and partial ureterectomy. This can be performed open, laparoscopic, or with robotic-assisted laparoscopy. The reported complications of pediatric partial nephrectomy include bleeding and loss of the remaining moiety from vasospasm or vascular injury. Multi-institutional studies have found this risk to be significant, ranging from 5% to 9% in a pediatric population, and the lifetime risk may even be higher.1 A 9-year retrospective, multicenter review of 25 children who underwent UPN found that although no patient had complete loss of the remnant moiety function, 17% had partial loss.2
There have been theoretical concerns about hypertension, infection, or malignancy developing in a retained dysplastic renal unit. Levy and colleagues note that hypertension in patients with or without retained dysplastic renal units was related to the presence of renal scarring following febrile UTI in the normal moiety.3 Husmann reported more than two decades ago that these complications are sporadic and a retained dysplastic renal unit does not require extirpative surgery on that basis alone.4
Additionally, with an upper tract approach, ureteral remnants do not need to be addressed surgically in most cases (88%).5 Previously, if a patient had a UTI after undergoing a partial nephrectomy and had a refluxing short ureteral remnant or a decompressed ureterocele, the UTI was attributed to the ureteral remnant alone without considering a dysfunctional voiding pattern as the possible cause of a non-complicated UTI. When the IUU is performed proximally, a long stump with large diameter may account for UTI.5
In the present case, the family did not want extirpative surgery. Since this index case in 2012, select functioning and non-functioning lower pole moieties with associated high-grade reflux (grade 5; some grade 4) have been managed with IUU. For functioning lower pole moieties, the IUU obviates the need for open bladder surgery and definitively results in reflux resolution. We have employed the IUU for non-functioning or poorly functioning upper pole moieties with equal success. When performed in early infancy, we have often seen improvement in parenchymal thickness based on Color Doppler flow and the resistive index (RI).
Many surgeons will place a double J stent, but this requires a second anesthetic for removal. Leaving a string in a diapered infant or child is less desirable. With the ongoing controversy surrounding the concerns of neurotoxicity from anesthesia in infants and young children, we leave only a Penrose drain.6 To date, no complications have occurred, and the Penrose drain is removed at about 1 week.
The IUU is not a new operation. Many of us avoided anastomosing a massively dilated thick-walled ureter to no more than a “thread” at times. In 1987 and again in 2001, the Kaplan group in San Diego reported on a large series of IUU showing that even the largest ureters anastomosed to the smallest recipient ureters do well.7,8 This is certainly the case because obstruction after an IUU is a rare phenomenon.
Recently, several institutions have presented on this surgical shift from partial nephrectomy to IUU for treatment of very poorly or non-functioning moieties.9,10 Shukla and colleagues at the Children’s Hospital of Philadelphia compared IUU in upper pole systems with and without significant demonstrable function.9 Results in this study were comparable for both robotic and open IUU. Most of the complications reported were stent related with rare febrile UTI. They conclude that clinical and radiological long-term outcomes show no adverse impact on the renal function of the involved moiety, whether addressed open or via another minimally invasive technique. In 2009, Hildalgo-Tamalo and colleagues coined the term open minimally invasive surgery.11 Gaining exposure through a very short inguinal incision (<3 cm) and remaining retroperitoneally represents the most non-invasive way to perform this surgery.
Ureteroureterostomy for non-functioning or poorly functioning moieties of duplex systems can be successfully used, obviating the need for upper tract extirpative surgery. We have shown the application of the IUU for the definitive treatment of lower pole high-grade reflux when the upper pole moiety is normal. The IUU should be considered as part of the surgical armamentarium for treating high-grade reflux in a duplex system. The IUU is relatively easy to perform with excellent success rates and rare complications.