Computed tomography urography: trends in positivity rates over time

To investigate changes in usage of computed tomography urography (CTU), indications for CTU, and rates of positive findings over time.

Retrospective review of data from April 2000 to December 2005 assessed rates of overall positive findings, rates of suspected transitional cell carcinomas (TCCs), benign genitourinary (GU), and significant non-GU findings. Data were analyzed based on specialty of ordering physicians and on requisition indications.

One thousand two hundred seventy-one patients had 1746 CTUs, including 952 men (1259 studies) and 319 women (487 studies) with mean age of 61 years. Computed tomography urographies increased from 265 in 2001 to 443 in 2004. Eighty-nine percent were ordered by urologists, 4% by oncologists, 1% by emergency physicians, and 6% by other specialties. Sixty-two percent of first-time studies were ordered for possible GU malignancy, 24% for hematuria, and 14% for other reasons. Eight hundred sixty-one examinations (49%) showed significant findings. The rate of all positive examinations, analyzed in 6-month periods, varied from 37% to 54%, but no time trend was identified. First-time patient examinations had positive examinations in 46% to 62% of cases. Similarly, no trends were found for examinations interpreted as possible TCC (17%-32%), renal stones (9%-18%), renal masses (1%-6%), causes of hematuria (15%-26%), and acute non-GU findings (2%-9%). The rate of positive findings by ordering specialty varied minimally from 49% to 53%. No change occurred in the proportions of indications for CTU over time.

In 5 years, the number of CTU examinations per year increased 1.5-fold. The rate of CTU findings positive for suspected TCC, stones, and other causes of hematuria showed no decline or increase. If precautions are taken regarding proper indications for CTU, the overall rates of positive findings may not substantially change over time, thereby only submitting high-risk patients to this examination.