Distal Ureteral Calculus or Deflux Calcification?

Abstract

Background: There have been >50,000 dextranomer-hyaluronic acid implants performed since 2001, and each has the potential to calcify. Although they are most often asymptomatic, these calcifications may mimic large distal ureteral calculi and are often misidentified on CT performed for suspected urolithiasis or other complaints.

Case Presentation: We report the case of a 21-year-old woman who presented with symptoms consistent with obstructive uropathy who was reported to have bilateral ureteral-vesicular junction calculi on abdominal CT evaluation. On further questioning she relayed the history of a vague urologic procedure as a child but was unable to characterize it further. On the basis of her relatively mild symptoms, urinalysis and renal ultrasonography were obtained demonstrating bilateral ureteral jets and she was diagnosed with nonobstructing bilateral dextranomer-hyaluronic acid calcifications and a presumed urinary tract infection that resolved with empiric antibiotic therapy.

Conclusion: Accurate diagnosis of implant calcification is critical to effective therapy and avoiding unnecessary radiation or anesthesia. This diagnosis should be suspected with radiologically demonstrated large ureteral calculi but relatively mild presenting symptoms. As dextranomer-hyaluronic acid implantation is routinely performed in young patients it is also possible that this relevant history will not be reported.

Introduction

Over the years endoscopic injection of dextranomer-hyaluronic acid (Deflux^®) has become a preferred method of addressing vesicoureteral reflux (VUR). Since FDA approval in 2001, there have been >50,000 Deflux procedures performed.¹ Although this procedure is generally well tolerated and effective it is not without complications. One complication reported sporadically in the literature¹ is implant calcification and inflammation, which may progress for years before becoming symptomatic and thus be unclearly correlated with the initial procedure. Taken together this progression may mimic the presentation of large distal ureteral calculi, particularly on abdominal CT.

Case Presentation

We present the case of a 21-year-old woman who was treated for VUR 10 years ago through an unknown procedure. At presentation to her primary care physician she complained of low back pain and urinary frequency without hematuria for 3 days. She was found to have mild left costovertebral angle tenderness on initial examination. Consequently she received a scout kidney, ureter, and bladder radiograph (KUB) as part of an abdominal CT protocol for further evaluation of presumed urolithiasis. The scout KUB revealed a left-sided ureterovesicular junction (UVJ) opacity, Figure 1, which the CT further characterized as a 1.5 cm diameter calculus adjacent to the left UVJ with a similarly sized calculus next to the right UVJ (Fig. 2a, b). She was then referred for urgent urologic evaluation for bilateral ureteral calculi.

FIG. 1.

Initial Scout kidney, ureter, and bladder radiograph showing a poorly defined left opacity, indicated by the red arrow, near the ureterovesicular junction.

FIG. 2.

Saggital (a) and axial (b) abdominal CT exhibiting bilateral distal ∼1.5 cm diameter calcifications at the ureterovesicular junctions, indicated by red arrows, without frank hydronephrosis.

Her reported symptoms were somewhat milder than those typically associated with intraluminal stones of this size. In addition, the lack of substantial hydronephrosis suggested an intact lumen. In the setting of her reported symptoms and physical examination with the history of an unknown past urologic procedure, the diagnosis of Deflux calcification was suspected. The patient had a positive urinalysis and was treated for presumed urinary tract infection (UTI). Her symptoms improved on antibiotics and a repeat urinalysis demonstrated resolution of UTI with a normal urinalysis. Since the patient has only had a single urinary tract infection since her Deflux procedure and her symptoms resolved quickly with antibiotics, no further work-up was elected by the patient and urologist. However, we discussed performing a cystoscopy to assess for possible urothelial disruption or tear if her symptoms recurred. At 4 months follow-up she remains asymptomatic with a normal urinalysis. Her symptoms improved within days and her laboratory results remained normal. Renal ultrasonography demonstrated bilateral ureteral jets, confirming the nonobstructive nature of the calcifications and further suggesting the diagnosis of Deflux calcification. She was advised to follow up for annual kidney function evaluation and renal ultrasonography to monitor for silent hydronephrosis. She was also advised to call or return sooner if symptoms returned.

Discussion

The pathogenesis of dextranomer-hyaluronic acid implant calcification is thought to be multifactorial and to directly correspond with local hematoma formation related to injected material and granulomatous reactions to the presence of a foreign body. Owing to the pathogenesis, time frames for this process are highly variable and one case series noted 2–3 years of nondescript annual follow-up ultrasonographies before unilateral or bilateral calcifications were noted.² Previous reports measure calcification rates approximating 2% at 4 years postprocedure,¹ which in conjunction with the reported 50,000 injection procedures by 2011¹ suggests substantial and increasing community prevalence.

A thorough urologic history and physical examination is crucial to the practicing endourologist. Patients with a history of Deflux injection may present unique challenges and be initially misdiagnosed by an interpreting radiologist or referring physician.

Deflux calcifications are often misinterpreted radiologically as distal ureteral calculi.^1–3 Given the extraluminal location of Deflux injections, subsequent calcification is unlikely to obstruct the ureter. In our experience, ultrasonography is a particularly helpful imaging modality as it may further suggest UVJ patency by demonstrating urethral jets. In most patients with calcified Deflux implants, further evaluation of an atypical radiologic finding is not helpful and may entail unnecessary radiation or anesthetic exposure.³

Certain patients with a history of Deflux injection may warrant screening ultrasonographies to assess for silent hydronephrosis. We suggest annual screening ultrasonography in patients with known calcified Deflux, those with a history of urolithiasis, or chronic kidney disease. Particularly in sexually active women, UTIs may exacerbate the presentation or progression of Deflux calcifications. Rarely, patients will present with true obstruction from extrinsic ureteral compression by calcified Deflux and its surrounding inflammatory reaction or persistent VUR despite Deflux implantation.⁴ In either case these patients may require definitive surgical management through ureteral reimplant with concomitant removal of the obstructing calcification.⁴

This case reinforces the value of a thorough patient history and clinical correlation with radiologic findings.

Conclusion

Endoscopic injection of dextranomer-hyaluronic acid (Deflux) has become a common method of addressing VUR since its approval in 2001. Patients who undergo Deflux injection may present unique challenges to the practicing urologist. A thorough urologic history and physical examination is crucial to identify these patients and treat them appropriately.

Abbreviations Used

CT

computed tomography

KUB

kidney, ureter, and bladder radiograph

UTI

urinary tract infection

UVJ

ureterovesicular junction

VUR

vesicoureteral reflux

Author Disclosure Statement

No competing financial interests exist.

Cite this article as: Spencer E, Baber J, Ferretti M (2019) Distal ureteral calculus or Deflux calcification? Journal of Endourology Case Reports 5:4, 178–180, DOI: 10.1089/cren.2019.0058.