Podium Session

Poster, Podium & Video Sessions

PD11-05: Contrast-enhanced ultrasound as a replacement for fluoroscopic nephrostogram following percutaneous nephrolithotomy

Friday, May 12
1:40 PM - 1:50 PM
Location: BCEC: Room 251

Presentation Authors: Thomas Chi*, Manint Usawachintachit, David Tzou, Helena Chang, Benjamin Sherer, Marshall Stoller, Stefanie Weinstein, John Mongan, San Francisco, CA

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.


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.


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.


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.

Source Of Funding: NIH R21-DK-10943

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