Login to Access Video or Poster Abstract: MP75-19
Sources of Funding: none

Introduction

Imaging after ureteroscopy (URS) and shockwave lithotripsy (SWL) is suggested by the American Urologic Association to ensure stone fragment clearance, resolution of hydronephrosis, and rule out ureteral stricture formation. To our knowledge, no prior studies have examined large-scale national imaging patterns after procedural intervention for nephrolithiasis. We sought to characterize imaging utilization patterns after URS and SWL.

Methods

Using Marketscan, a private employer-based insurance database, we identified patients 17-64 years old undergoing URS or SWL between 2007-2014. A minimum of 12 months of enrollment was required and patients were excluded if they received more than 1 lithotripsy procedure of any type within 90 days. Imaging modalities identified by CPT and ICD-9 codes included computed tomography (CT), renal ultrasound (US), abdominal X-ray (KUB), and intravenous pyelogram (IVP), and were tracked postoperatively. Utilization patterns by demographic factors were assessed using chi-squared test.

Results

A total of 100,710 patients met inclusion criteria following URS, with 39% having no post-operative imaging within 12 months. Only 45% underwent imaging within 3 months of URS, most commonly KUB (28%). At 3, 6, and 12 months, only 26%, 33%, and 42%, respectively, of URS patients had any anatomic imaging (US, CT, or IVP). A total of 109,237 patients met inclusion criteria following SWL, with 16% having no postoperative imaging within 12 months. 78% underwent imaging within 3 months; most commonly KUB (69%). By 3, 6, and 12 months, 19%, 26%, and 36%, respectively, of SWL patients had any anatomic imaging. _x000D_ KUB was the most common imaging modality after either intervention type (38% of URS, 74% of SWL) within 12 months, followed by CT (25% of URS, 24% of SWL), then US (23% of URS, 17% of SWL). Over the 7 year study interval US increased by 10% after URS and 6% after SWL, while CT use decreased by 4%. Older age and female sex were independently associated with higher rates of imaging (p<0.001). US use was 13% higher in the Northeast, and more likely to be utilized in patients in metropolitan statistical areas or enrolled in health maintenance organizations._x000D_

Conclusions

Despite recommendations for routine imaging after stone procedures, a large proportion of insured patients received none, especially following URS. The majority of URS and SWL patients did not receive any postoperative anatomic imaging, which may raise the risk of undiagnosed ureteral strictures, silent obstruction, and renal function loss. Although RUS use is slowly increasing, it remains underutilized compared to CT.

Funding

none