Rationale use of unenhanced multi-detector CT (CT KUB) in evaluation of suspected renal colic

To assess the yield of non-contrast enhanced CT (CT KUB) across different ordering specialties and need of developing an algorithm for its rationale use.

We retrospectively reviewed 1550 consecutive CT KUB studies requested for suspected renal colic carried out at a single institution in a calendar year. The data was analyzed for demographic characteristics, referring clinician and final diagnosis. Only patients with CT as primary imaging for clinically suspected reno-ureteral colic were included. Departments ordering these CT KUB examinations were divided into three divisions: Urologist, emergency room (ER) physician and others.

Of 1550 CT KUB performed in the study period 766 met the inclusion criteria. Urologists (57%), followed by ER physicians (30%) mostly ordered the examination. The overall positive yield for urolithiasis was 64% (n = 490), rate of incidental/alternate findings was 15% (n = 116) and 21% (n = 160) were negative. Urologist has the highest positive yield of 67.4% (n = 295) followed by ER physician 67% (n = 152) and others 42.5% (n = 43); p < 0.001. Rate of incidental/alternate findings was highest in CT ordered by other specialties 23.7% (n = 24) followed by ER physician 17.6% (n = 40) and urologist 11.8% (n = 52); p = 0.005.

There is statistically significant difference of yield across specialties. CT KUB as an initial imaging modality for suspected urolithiasis should be ordered in consultation with the urologist and ER physicians. Tool of good history taking and physical examination has proved to be essential steps in algorithm of ordering CT KUB, which can avoid unnecessary radiation exposure.