NEW ORLEANS, LA USA (UroToday.com) - Imaging is a crucial component of preoperative evaluation in patients with urolithiasis. Non-contrast computerized tomography (NCCT) is the gold standard for diagnosis of ureteral stones. However, ionizing radiation associated with CT imaging has raised concerns about potential malignancy risks and this has engendered surgeon to modify or come up with low-radiation protocols or imaging modalities with no radiation. Ultrasound is an affordable and easily accessible technology. Authors from UAE conducted a study to prospectively compare two imaging modalities -- CT and color Doppler ultrasound in diagnosis and follow up of ureteral stones with report on management outcomes.
The study included a total of 494 consecutive patients with symptomatic lower ureteral stones. All patients underwent either immediate NCCT or color Doppler ultrasound (CDU). The results of both techniques were blinded to both the radiologist and ultrasound technician. Two urologists independently collected and analyzed the data. Stone characteristics were obtained -- as well as patient characteristics -- and analyzed. The follow up consisted of imaging performed with one of the modalities compared in the study every 2-4 weeks.
Mean stone size was 6.9 mm. Authors divided patients into different stone-size groups including < 5 mm (28.7%), 5-10 mm (67.8%), > 17 mm (3.4%).
They demonstrated that NCCT was able to detect ureteral stones in over 99% of cases, and only 0.4% were negative. CDU was able to detect stones in concordance with NCCT in 475 (96.2%) and negative in 19 (3.8%), which was significantly lower than NCCT.
The authors concluded that lower ureteral stones could be followed up successfully by color Doppler ultrasound. It is a safe, low radiation, and reliable alternative to NCCT in follow up of lower ureteric stones.
There was a discussion on false-positive and false-negative rates of CDU. The authors affirmed that both false-positive and false-negative rates are extremely low for CDU and represent less than 5%. However, surgeons should remain cautious about false-positive and false-negative rates and properly follow up with patients when there is any doubt that CDU is not accurate.
Presented by Ravi Kadasne, Chandrashekar Anjikar, and Mahmoud Abdel-Gawad at the American Urological Association (AUA) Annual Meeting - May 15 - 19, 2015 - New Orleans, LA USA
Al ain, United Arab Emirates
Reported by Zhamshid Okhunov, MD (University of California-Irvine), medical writer for UroToday.com