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Ureteral Obstruction Secondary To Endoscopic Treatment With Polydimethylsiloxane: Case Report And Review Of Literature

Santiago Vallasciani¹, Alfredo Berrettini¹, Letterio Runza², Germana Bassi¹, Valeria Tringali¹,Gianantonio Manzoni¹
¹Pediatric Urology Unit, IRCCS Ca’ Granda - Ospedale Maggiore-Policlinico
²Anatomopathology Service, IRCCS Ca’ Granda - Ospedale Maggiore-Policlinico



A case of vesico-ureteral obstruction after endoscopic treatment of left high-grade vesico-ureteral reflux with polydimethylsiloxane is presented. Despite its low invasiveness, endoscopic vesicoureteral reflux treatment presents complications. Ureteral obstruction was evidenced in different series ranging from 0.2 to 8.33%. In the present case, we hypothesize that the combination of Hydrodistention Intraureteral Technique (HIT) and Polydimethylsiloxane may have played a role in the creation of the vesico-ureteral junction obstruction. The present review of the literature is limited by an inability to compare the incidence of vesico-ureteral junction obstruction. Future studies should be done to determine the most significant factors contributing to this rare but dangerous complication.

Key-words: vesico-ureteral reflux/therapy, ureteral obstruction, postoperative complications

This paper was presented at the 27th Congress of the Società Italiana di Urologia Pediatrica (SIUP), Padua, 21st-24th September 2011



Vallasciani Santiago
Pediatric Urology Unit
IRCCS Ca’ Granda - Ospedale Maggiore-Policlinico,
Via della Commenda 10
20122 - Milan, Italy
email:  This email address is being protected from spambots. You need JavaScript enabled to view it.



Endoscopic treatment of vesico-ureteral reflux (VUR) is increasing and its use has been progressively extended to high grades particularly after introduction of Hydrodistension Intraureteral Technique (HIT). Over the years, different materials have been used. This procedure, however, is not free of complications. We report a case of ureteral obstruction after endoscopic treatment of VUR with HIT-Polydimethylsiloxane, review the literature on this subject, and discuss technical aspects of injection and materials.

Material and Methods

A 5-year-old girl was referred to our centre two years after endoscopic (HIT) treatment of left high grade VUR with Polydimethylsiloxane (2 ml). Six months after the procedure the patient presented with recurrent urinary tract infections (UTI). Serial Ultrasounds (US) revealed a progressive increase in left ureteral and renal pelvis dilatation. MAG3 renal scan and indirect cystoscintigram showed conserved renal function, obstructed and dilated left ureter without VUR. The patient underwent uretero-neo-cystostomy according to Cohen technique with excision of the terminal obstructed ureter. Macroscopic examination of the excised ureter revealed the presence of the bulking material encircled by inflammatory-type tissue that had strong adhesions with the surrounding structures (Figure 1).

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Figure 1: Intraoperative picture showing position of the bulking agent that migrated in an extra-vesical position

Microscopic examination of the terminal ureter showed acute and chronic inflammatory reaction associated with the Polydimethylsiloxane at the periureteral area (Figure. 2). A sample lymph node close to the ureter showed the presence of birefringent unknown material that was highly suspicious for residual Polydimethylsiloxane.

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Figure 2: Histological picture of excised distal ureter showing birefringent material at the ureteral wall (yellow star)


After an 18-month follow up the patient is asymptomatic and no dilations were seen at the subsequent US scans.


Endoscopic treatment of VUR has gained popularity among pediatric urologists since its introduction in 1980’s. [1] Several materials have been utilized with variable results in terms of VUR resolution reported.

Despite its low invasiveness, complications after endoscopic treatment of VUR have been reported. Among them, ureteral obstruction was evidenced in different series ranging from 0.2 to 8.33% as depicted in Table 1. [2,3,4,5,6]

Table 1. Series of UVJ obstruction after endoscopic VUR treatment. Type of bulking agent are described (C: collagen; M®: Polydimehyilsiloxane; D®: Hyaluronic Acid/Dextranomer polymer) with % of obstruction for each subgroup.



n° ureters

Bulking agent

Obstruction %




Dawrant MJ












Vandersteen DR











Escala Aguirre JM













Serrano Durba A












Bartoli F
























No single factor was identified to be the most relevant in the development of the vesico-ureteric junction obstruction. Injection technique of bulking agent was present in equal distribution among different series and data regarding volume of injection and/or type of obstruction (transient or permanent) is missing in most of the series presented in the literature.

A warning on morphology and anatomy of the vesico-ureteric junction (VUJ) was raised by Snodgrass who reported a case of a 2-year old girl with obstruction after endoscopic VUR treatment with Dextranomer/Hyaluronic Acid polymer in dysmorphic appearing refluxing ureters. [7]

The type of bulking agent may have some relationship with the degree of obstruction. Lopez Dias et al performed a histological examination of VUJ in cases where endoscopic VUR treatment with different bulking agents was ineffective and subsequent open surgery was performed. They found that the most intense inflammatory response was found after Teflon or Polydimethylsiloxane injection with foreign body reaction, persistence of bulking material and intense macroscopic adhesions. On the other hand, Dextranomer/Hyaluronic Acid polymer was observed to generate a lower foreign body reaction. Furthermore, the Dextranomer spheres (previously filled with Hyaluronic Acid) were now filled with native collagen.[8] Nevertheless, a statistical analysis using the Fisher’s exact 1-tail test (performed at PersonTime2/PersonTime2.htm website) comparing the incidence of obstruction in the group of reports present in Table 1 showed no statistical significative difference between Polydimethylsiloxane and Dextranomer/Hyaluronic Acid polymer groups (p = 0.19).

The volume of injection may not be related to the risk of obstruction. In a recent report by Sorensen et al. [9] of more than 4,000 cases treated with Dextranomer/Hyaluronic acid polymer in a 6-year period, they observed an increase in volume of substance injected per patient. This increase in volume had an impact on improving results in terms of VUR resolution but did not increase the incidence of VUJ obstruction.

The original injection technique as described by Puri et al. [1] was initially limited to the low grade VUR and later extended to high-grade cases. In addition, for the latter group a particular modification in the injection technique was proposed by Kirsch in 2004, the so-called Hydrodistention Intraureteral Technique (HIT). An increase in the incidence of VUJ obstruction with this modification was not reported after 3 months follow up when Dextranomer/ Hyaluronic acid polymer was used as the bulking agent. [10]

In the present case, we hypothesize that the combination of HIT and Polydimethylsiloxane may have played a role in the creation of the VUJ obstruction.

Furthermore, pathologic examination revealed that the bulking agent was located deep into the ureteral wall rather than at the submucosal level (Figure 2). This may also be related to an abnormal anatomy of the VUJ, hypothesis already raised by Snodgrass in 2004. [7] The intraureteral/ periureteral spillage of the bulking agent plus the high-grade inflammatory response of the Polydimethyilsiloxane may have been the main causes of structural changes in the terminal ureter resulting in a fibrotic and stenotic VUJ.

In addition, the presence of birefringent material in a lymph node close to the ureter may be secondary to a migration of a misplaced injection. In fact, Polydimethyilsiloxane migration has been reported in an experimental study related to an improper injection technique. [11] The present review of the literature is limited by an inability to compare the incidence of VUJ obstruction among different studies. Lack of unified criteria in reporting duration of the obstruction (transient or permanent) was found. The method and timing of follow up were not properly standardized.

Future studies must be done to determine the most significant factors contributing to the rare but dangerous complication of ureteral obstruction following endoscopic therapy.

Financial support: none




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