Abstract: PD11-05
Sources of Funding: NIH R21-DK-10943

Introduction

Fluoroscopic nephrostogram is commonly used to evaluate ureteral patency after percutaneous nephrolithotomy. However, it can incur a significant exposure to ionizing radiation. We have reported feasibility and safety for contrast-enhanced ultrasound nephrostogram with collecting system microbubble contrast injection to obviate the need for radiation exposure. In this study, we compared contrast-enhanced ultrasound to fluoroscopic nephrostogram in evaluating ureteral patency after percutaneous nephrolithotomy. _x000D_

Methods

After obtaining institutional review board approval for off-label use of an ultrasound contrast agent, consecutive patients with kidney stones who underwent percutaneous nephrolithotomy at our medical center were eligible for enrollment in this prospective cohort non-inferiority study. Postoperative day 1 after surgery, contrast-enhanced ultrasound and fluoroscopic nephrostogram were performed within 2 hours of one other for each patient to identify ureteral patency, the primary outcome for this study. Results from both imaging studies were reviewed in a blinded fashion by two experienced radiologists and compared. _x000D_

Results

Eighty-six imaging studies were performed in 76 patients during the study period from September 2015 to September 2016. Females (58.3%) predominated males (41.7%) with a mean age of 51.2±16.1 years and a mean body mass index of 29.6±8.4 kg/m². Four studies were excluded due to technical factors preventing imaging interpretation. For the remaining 82 studies, 66 (80.5%) demonstrated concordance for detecting ureteral patency between the two imaging techniques. Within the 16 (19.5%) discordant studies,15 showed antegrade urine flow on contrast-enhanced ultrasound but not on fluoroscopic nephrostogram, and one antegrade flow on fluoroscopic nephrostogram but not on ultrasound. For discordant studies, 97.5% of tubes were managed according to ultrasound results. No adverse events were noted related to any contrast-enhanced ultrasound studies. While contrast-enhanced ultrasound utilized no ionizing radiation, fluoroscopic nephrostograms provided a mean radiation exposure dose of 13.1±17.5 mGycm² for patients. _x000D_

Conclusions

Contrast-enhanced ultrasound can be used to perform a nephrostogram with ultrasound contrast administered via a nephrostomy tube. This novel imaging technique is non-inferior to fluoroscopic nephrostogram, safe for patients, and devoid of radiation exposure in evaluating ureteral patency following percutaneous nephrolithotomy.

Funding

NIH R21-DK-10943