Asymptomatic chronic partial obstruction of a normal ureter following dextranomer/hyaluronic acid copolymer (Deflux®) injection for grade I vesicoureteral reflux

Endoscopic injection of bulking agents in pediatric vesicoureteral reflux: a narrative review of the literature

In the last 20 years, endoscopic injection (EI) has affirmed as a valid alternative to open surgery for management of pediatric vesicoureteral reflux (VUR). This study aimed to investigate and discuss some debated aspects such as indications, bulking agents and comparison, techniques of injection and comparison, predictive factors of success, use in specific situations. EI is minimally invasive, well accepted by patients and families, with short learning curve and low-morbidity profile. It provides reflux resolution rates approaching those of open reimplantation, ranging from 69 to 100%. Obviously, the success rate may be influenced by several factors. Recently, it is adopted as first-line therapy also in high grade reflux or complex anatomy such as duplex, bladder diverticula, ectopic ureters. The two most used materials for injection are Deflux and Vantris. The first is absorbable, easier to inject, has lower risk of obstruction, but can lose efficacy over time. The second is non-absorbable, more difficult to inject, has higher risk of obstruction, but it is potentially more durable. The two main techniques are STING and HIT. To date, the ideal material and technique of injection has not yet clearly established, but the choice remains dependent on surgeon's preference and experience.

Incidence and risk factors for calcification after dextranomer/hyaluronic acid (Dx/HA) copolymer injection for vesicoureteral reflux

INTRODUCTION

Since the first case of dextranomer/hyaluronic acid (Dx/HA) implant calcification in 2008, concern about the long-term sequelae of Dx/HA injection has been growing. According to previous reports, the incidence of Dx/HA calcification 4 years after injection would be around 2%.

AIM

The primary aim was to estimate the incidence of Dx/HA implant calcification after endoscopic treatment of vesicoureteral reflux in pediatric patients. Secondary objectives were to establish risk factors and to perform a survival analysis after Dx/HA injection.

STUDY DESIGN

Patients undergoing Dx/HA endoscopic injection from 2007 to 2014 were prospectively registered. The database included clinical, surgical and radiological outcomes. Patients that showed Dx/HA implant calcification during follow-up were compared to those who did not. Univariable and survival statistical analyses were performed.

RESULTS

30 implants calcified over 355 ureters endoscopically treated. Age at first treatment was lower in patients with implant calcification (2.4 ± 1.3 years vs 3.6 ± 2.5 years; p < 0.005). The risk of implant calcification was 8.45% (95% CI: 5.96-11.85%). Median follow-up was 7.6 years (IQR: 5.2-9.5). The incidence rate was 12.06 cases per 1000 ureters-year. The period of highest hazard of implant calcification was between 3 and 5 years after injection. The only risk factor related to implant calcification was the age at first injection: relative risk of implant calcification was 4.4 (95% CI: 1.6 to 12.4; p = 0.002) for patients first treated before the age of 3.5 years.

DISCUSSION

The risk and the incidence rate of Dx/HA implant calcification were higher than previous data. The period of highest hazard and detection of implant calcification were consistent with previous reports. Patients first treated before the age of 3.5 had shorter survival time without implant calcification. These are the first data about risk factors and survival function of Dx/HA implant calcification. However, our conclusions about the clinical significance of Dx/HA implant calcification were limited because the patients with implant calcification were asymptomatic. Further studies with larger sample and longer follow-up should confirm the clinical significance and life-long tendency of Dx/HA implant calcification.

CONCLUSIONS

The risk and the incidence rate of Dx/HA implant calcification were higher than expected. The hazard of calcification was higher between 3 and 5 years after injection. The risk was especially higher in patients treated before the age of 3.5. Caution should be taken not to confuse implant calcifications with ureteric stones. A 5-year follow-up would set a better understanding of the actual incidence and clinical significance of implant calcification.

What are the predictive factors leading to ureteral obstruction following endoscopic correction of VUR in the pediatric population?

BACKGROUND

It is extremely important to not only address the short-term success following endoscopic correction of vesicoureteral reflux (VUR) but also the long-term efficacy and safety of the tissue augmenting substance utilized for endoscopic correction.

OBJECTIVE

This study retrospectively evaluated all cases of ureterovesical junction (UVJ) obstruction following endoscopic treatment of VUR over the last 5 years utilizing two tissue augmenting substances, with special emphasis on the safety of Vantris^®, and performed clinical and histological review of these patients.

METHODS

The study population comprised 2495 patients who underwent endoscopic correction of VUR utilizing Deflux^® (1790) and Vantris^® (705). Tissue sections were stained with hematoxylin & eosin and trichrome, and examined under a light microscope. Nine primary obstructive megaureters after ureteral re-implantation served as controls.

RESULTS

Nine (0.5%) children (three female and six male) in the Deflux group and nine (1.3%) (five females and four males) in the Vantris group developed UVJ obstruction and required ureteral re-implantation. Obstruction developed during the period ranging 2-49 months (average 16 months) following endoscopic correction. The primary reflux grade was III in seven, IV in six, and V in six children. The mean volume of the injected material in all obstructed patients was 1.2 ± 0.6 cc (mean ± SD). Histopathological analysis revealed a pseudocapsule composed of fibrous tissue and foreign-body giant cells surrounding the Vantris implant in all patients. The distal part of the ureters demonstrated significant ureteral dilatation without ureteral fibrosis. In all patients, additional biopsies from the muscularis propria adjacent to the injection site were examined and showed no significant abnormalities. There was an increased collagen deposition in the juxtavesical segment of the obstructive ureters following Deflux and Vantris injections, and of primary obstructive megaureter. No significant difference was found in the tissue response between Deflux and Vantris patients and controls. Statistical analysis of the nonhomogeneous population demonstrated higher obstruction rates in patients from the Vantris group. However, no statistical difference was demonstrated regarding the obstruction rate in the homogenous group with relation to gender, age and reflux grade group of patients. Moreover, univariate analysis revealed that Grade V reflux, the presence of beak sign on the reviewed pretreatment, and inflamed bladder mucosa upon injection were significant independent risk factors leading to obstruction.

DISCUSSION

This study suggested that the underlining ureteral pathology lead to UVJ obstruction following Vantris injection. There was increased collagen deposition in the juxtavesical segment of the obstructive ureters following Vantris injection. Furthermore, these findings were similar to those discovered in patients who underwent endoscopic correction with Deflux, and in patients who required ureteral reimplantation due to primary obstructive megaureter. Additional biopsies from the muscularis propria adjacent to the injection site showed no significant abnormalities, ironing out the fact that Vantris did not led to adverse tissue reaction following injection. Univariate analysis further ironed out the hypothesis that underlying ureteral pathology was responsible for the increased incidence of UVJ obstruction and demonstrated that Grade V reflux, the presence of beak sign on the reviewed pretreatment VCUG, and inflamed bladder mucosa upon injection were significant independent risk factors leading to obstruction.

CONCLUSION

Data showed that Vantris injection did not lead to any different ureteral fibrosis or inflammatory changes to the tissue augmenting substances utilized in past and present clinical practice, and therefore did not seem to increase the incidence of UVJ obstruction. High reflux grade, presence of obstructive/refluxing megaureter and inflamed bladder mucosa were the only statistically significant and independent predictive factors for UVJ obstruction following endoscopic correction of VUR.

Prevesical Calcification and Hydronephrosis in a Girl Treated for Vesicoureteral Reflux

The endoscopic STING procedure using Deflux is a common and minimal invasive treatment for vesicoureteral reflux. Herein we present the case of an 11-year-old girl with loin pain and de novo hydronephrosis and megaureter on the left. Ultrasound and plain abdominal X-ray demonstrated a calcification at the ureterovesical junction. She had been treated with Deflux injections 5 years before. The clinical quiz addresses the differential diagnosis, workup, and pathogenesis of calcifications at the ureterovesical junction following endoscopic reflux therapy.

Controversies in the Management of Vesicoureteral Reflux

Vesicoureteral reflux (VUR) is the abnormal retrograde flow of urine from the bladder into the upper urinary tract. Diagnosis and subsequent management of VUR have become increasingly controversial, with differing opinions over which children should be evaluated for reflux, and when detected, who should undergo treatment. Management goals include prevention of recurrent febrile urinary tract infection (fUTI) and renal injury while minimizing the morbidity of treatment and follow-up. Management options include observation with or without continuous antibiotic prophylaxis and surgical correction via endoscopic, open or laparoscopic/robotic approaches. Management should be individualized and based on patient age, health, risk of subsequent renal injury, clinical course, renal function, and parental preference.

Late ureteral obstruction after endoscopic treatment of vesicoureteral reflux with polyacrylate polyalcohol copolymer

OBJECTIVE

To investigate the incidence and presentation of ureteral obstruction after endoscopic injection of polyacrylate polyalcohol copolymer (PPC) for the treatment of vesicoureteral reflux, and to analyze its possible causes, together with histopathologic assessment.

PATIENTS AND METHODS

The data of 189 patients who underwent endoscopic injection of PPC between May 2011 and December 2013 were retrospectively reviewed. After the injection, patients were followed up by urinalysis and ultrasonography monthly for 3 months. Control voiding cystouretrography was performed in the third postoperative month. Patients were then followed up by ultrasound every 3 months. If a new-onset hydroureteronephrosis (HUN) was observed, control ultrasound was performed monthly to follow the change in the degree of HUN. If a moderate or severe HUN was observed, technetium-99m mercaptoacetyltriglycine or dimercaptosuccinic acid scintigraphy was performed. For patients who needed open surgery, Cohen ureteroneocystostomy was performed. The distal 1 cm of the ureters was resected and examined histopathologically.

RESULTS

One hundred eighty-nine patients with 268 refluxing ureters underwent endoscopic injection of PPC. Ureteral obstruction was observed in 3 ureters (1.1%), in 3 female patients of whom the degrees of reflux were grade 4, 5, and 5, respectively. Obstruction showed late onset in all 3 patients. Manifestations of obstruction included pain in 2 patients and recurrent febrile urinary tract infection with loss of function in scintigraphy in 1. All 3 patients underwent open ureteroneocystostomy.

CONCLUSION

PPC may cause ureteral obstruction several months or even years after injection. Patients who undergo endoscopic treatment of PPC need long-term follow-up, despite reflux showing complete resolution.

Incidence of Deflux® calcification masquerading as distal ureteric calculi on ultrasound

OBJECTIVE

Dextranomer-hyaluronic acid (Deflux(®)), the most widely used compound in the endoscopic treatment of vesico-ureteric reflux (VUR) today, is believed to provoke only minimal inflammation. Reports of calcification of Deflux(®) are increasing. We ascertain the incidence of Deflux(®) calcification appearing as distal ureteric calculi on ultrasound.

METHODS

Three cases (2 external patients) of ureteroscopy for calcified submucosal Deflux(®) prompted a retrospective review of the notes and imaging of all children treated with Deflux(®) for VUR between December 2000 and January 2011 at Great Ormond Street Hospital.

RESULTS

232 children (M:F = 5:3) received Deflux(®) for VUR at median age 2 years (range 2 months-12 years). Follow-up annual ultrasound, performed in all, identified calcification in 2. The interval between Deflux(®) injection and presentation of its calcification was 4 years. 104 of the 232 children had been followed up for 4-10 years. Considering the observed lag-period, after 4 years the incidence of calcification of Deflux(®) on ultrasound was 2% (2/104).

CONCLUSIONS

Patients should be warned that calcification of Deflux(®) can occur. Misinterpretation as ureteric stones is common and may lead to unnecessary ureteroscopy. In this series, the incidence of calcification of Deflux(®) on ultrasound after 4 years was 2%.

Postoperative ureteral obstruction after endoscopic treatment of vesicoureteral reflux with polyacrylate polyalcohol copolymer (Vantris®)

PURPOSE

To investigate the incidence and presentations of ureteral obstruction following periureteral injection of polyacrylate polyalcohol copolymer (PPC) for the treatment of vesicoureteral reflux (VUR).

MATERIALS AND METHODS

From Jan 2010 to Dec 2012, 88 patients (28 male, 60 female) with 128 renal refluxing units (RRU), 131 ureters and a mean age of 6.7 ± 5.9 years (range: 4 months to 32 years) underwent endoscopic correction of their VUR, using PPC. Exclusion criteria were dysmorphic appearing distal ureter, extravesical position of the ureteral orifice, persistent urethral obstruction (e.g. after previous valve ablation) and severe bladder trabeculation, making ureteral orifice unidentifiable. Patients were followed up by ultrasound one month after the injection and then every three months. Cystography was performed 3 months post-operation. Mean follow-up time was 13.1 ± 6.8 months (range: 3-27 months).

RESULTS

Two patterns of obstruction were observed: early, during the first 3-4 days post-operation, in four patients (4 ureters; 3%) which was associated with transient hydroureteronephrosis (HUN) in 2 patients (2 ureters; 1.5%); and late-onset obstruction in 3 patients (4 ureters; 3%) which appeared 3 months to 1 year after surgery. It manifested itself by urinary tract infection and uremia in one patient with bilateral obstruction but was asymptomatic in the other two. Early obstruction was managed expectantly and resolved in 3-12 months; however, late-onset obstruction needed catheter placement or open ureteroneocystostomy.

CONCLUSIONS

Patients who undergo endoscopic treatment for their VUR using PPC need long-term follow up until the safety of this substance is confirmed.

Acute and delayed vesicoureteral obstruction after endoscopic treatment of primary vesicoureteral reflux with dextranomer/hyaluronic acid copolymer: why and how to manage

OBJECTIVE

To present our cases of ureteral obstruction after endoscopic treatment of vesicoureteral reflux (VUR) with dextranomer/hyaluronic acid (Dx/HA).

PATIENTS AND METHODS

We collected data from patients who had suffered ureteral obstruction after endoscopic treatment of VUR with Dx/HA in our institution.

RESULTS

From April 2002 to April 2011 we treated endoscopically 475 ureters with VUR, and detected 5 ureteral obstructions. Median age at reflux treatment was 39 months. Reflux grade before treatment was III in one patient and IV in four. Three ureterovesical junctions (UVJ) were blocked after a second endoscopic treatment. The median of Dx/HA injected was 1 ml (0.6-1.1). In two patients ureteral obstruction presented acutely and was treated with a ureteral stent. In the other three, the ureteral obstruction appeared gradually and was detected by ultrasound scans and MAG3 diuretic renogram; one underwent nephrectomy because of poor renal function, and the other two were treated with endoscopic dilatation of the UVJ. In all these patients both reflux and obstructions have resolved.

CONCLUSIONS

On preoperative cystography, three of the patients had a narrowed distal ureter, and probably had a refluxing and obstructive megaureter. Other causes are not clear, except for those patients with acute presentation in whom edema of the UVJ was found. Ureteral obstruction after endoscopic treatment of VUR is rare. Endoscopic intervention such as ureteral stent placement or high-pressure balloon dilatation of the UVJ has good results as a treatment of acute and delayed obstruction.

Delayed-onset ureteral obstruction after endoscopic dextranomer/hyaluronic acid copolymer (Deflux) injection for treatment of vesicoureteral reflux in children: a case series

We report 4 patients with upper urinary tract (UUT) obstruction requiring ureteric reimplantation at 1, 7, 28, and 63 months after dextranomer/hyaluronic acid copolymer (Dx/HA) injection for vesicoureteric reflux. Histopathologic evaluation of ureteric segments revealed extensive foreign body formation in all cases. We conclude that UUT obstruction is a rare but serious complication after Dx/HA injection that can occur even years after surgery. The incidence of delayed-onset UUT obstruction may be higher than previously noted. Long-term follow-up and a critical reappraisal of the method are needed to assess the late sequelae of Dx/HA injection therapy for vesicoureteric reflux.

[Primary vesicoureteral reflux]

The never ending discussion about the diagnostics and treatment of vesicoureteral reflux (VUR) now includes arguments for diagnostic nihilism as well as invasive diagnostics and therapy, which is reminiscent of the debate on prostate cancer in adulthood. The common goal of all currently competing diagnostic strategies and approaches is the prevention of renal scars by the most effective and least burdensome approach. There is a difference between acquired pyelonephritic scars with VUR (acquired reflux nephropathy) and congenital reflux nephropathy (primary dysplasia) which cannot be influenced by any therapy.The VUR can be verified by conventional radiological voiding cystourethrography (VCUG), by urosonography, radionuclide cystography or even by magnetic resonance imaging (MRI). The guidelines of the European Association of Urology/European Society for Paediatric Urology (EAU/ESPU) recommend radiological screening for VUR after the first febrile urinary tract infection. Significant risk factors in patients with VUR are recurrent urinary tract infections (UTI) and parenchymal scarring and the patients should undergo patient and risk-adapted therapy. Infants with dilating reflux have a higher risk of renal scarring than those without dilatation of the renal pelvis. Bladder dysfunction or dysfunctional elimination syndrome represents a well-known but previously neglected risk factor in combination with VUR and should be treated prior to any surgical intervention as far as is possible.Certainly not every patient with VUR needs therapy. The current treatment strategies take into account age and gender, the presence of dysplastic or pyelonephritic renal scars, the clinical symptoms, bladder dysfunction and frequency and severity of recurrent UTI as criteria for the therapy decision. The use of an antibacterial prophylaxis as well as the duration is controversially discussed. Endoscopic therapy can be a good alternative to antibacterial prophylaxis or a surveillance strategy in patients with low grade VUR. In patients with dilating VUR and given indications for surgery, endoscopic treatment can be offered. However, parents should be completely informed about the significantly lower success rate of endoscopic therapy compared to open surgical procedures. The open surgical techniques guarantee the highest success rates and should be used in patients with a dilating VUR and high risk of renal damage.

Symptomatic bilateral delayed partial ureteral obstruction after bilateral endoscopic correction of vesicoureteral reflux with dextranomer/hyaluronic acid polymer

Endoscopic correction of vesicoureteral reflux using dextranomer/hyaluronic acid copolymer (Deflux) is a widely used technique. Complications are uncommon, and ureteral obstruction occurs particularly infrequently. We present a case of delayed symptomatic partial bilateral ureteral obstruction after bilateral high-volume (>1.0 mL) Deflux injections that required surgical repair 16 months after injection (Clavien classification IIIb.) Bilateral delayed obstruction after endoscopic correction of vesicoureteral reflux has not been previously reported. Previous reports of immediate and delayed ureteral obstruction after Deflux injection are reviewed.