Contrast-enhanced ultrasound (CEUS) nephrostogram: utility and accuracy as an alternative to fluoroscopic imaging of the urinary tract

Abstract

Aim: To establish the feasibility and accuracy of contrast-enhanced ultrasound (CEUS) nephrostogram in comparison to the reference standard, fluoroscopic nephrostogram, in providing alternative imaging of the urinary tract post-nephrostomy insertion.

Materials and methods: This prospective study was approved by the institutional and national ethics committee. All patients for whom a fluoroscopic nephrostogram was requested were included. Fluoroscopic and CEUS nephrostograms were performed within 24 hours. Image analysis (nephrostomy position, opacification of pelvicalyceal system, ureter, and bladder) was performed by two reviewers, and the diagnostic accuracy of the CEUS nephrostograms was compared to fluoroscopic nephrostograms.

Results: Sixty-two nephrostograms were performed in 48 patients from June 2011 to April 2016, (male: 25/48, 52.1%; mean age 65 years, range 28-90 years). Indications for nephrostomy were: malignancy (29/62; 46.8%), benign ureteric stricture (14/62; 22.6%), urinary diversion (8/62; 12.9%), renal calculus (5/62; 8.1%), haematoma (3/62; 4.8%) or pelvi-ureteric junction obstruction (3/62; 4.8%). Two nephrostomies were identified as displaced by both techniques. The pelvicalyceal system was visualised in 60/60 (100%) examinations in both fluoroscopic and CEUS nephrostograms. The entire ureter was visualised in 30/60 (50%) with CEUS compared to 32/60 (53.3%) fluoroscopically. The distal ureter was the least well-visualised segment for both techniques with no significant difference (p=0.815). Both CEUS and fluoroscopy could be used to correctly identify complications including entero-ureteric fistula or urine leak. Fluoroscopic nephrostogram demonstrated drainage into the bladder in 33/60 (55%), CEUS confirmed drainage in 34/60 (56.7%) cases (p=0.317).

Conclusions: CEUS nephrostogram can determine the correct positioning of a nephrostomy and assess drainage into the bladder with statistically comparable results to fluoroscopy.