Genitourinary abnormalities in an asymptomatic screening population: findings on virtual colonoscopy

The true incidences of genitourinary conditions in the modern era are not completely known. We sought to determine the incidence of genitourinary abnormalities in a group of asymptomatic adult patients undergoing axial imaging with virtual colonoscopy.

We performed a post-hoc analysis of imaging results from a prospective, IRB-approved study that randomized patients to screening "virtual" CT colonography (CTC) followed by standard endoscopic colonoscopy. CTC scans were reviewed separately by an independent radiologist and a urologist for genitourinary abnormalities. Genitourinary abnormalities were characterized as of minor, moderate, or major clinical significance. Identified nephroliths were categorized by location, laterality, size, and number. Student's t-tests and Fisher's exact-tests were used for continuous and categorical variables as appropriate.

Of 490 patients undergoing CTC and eligible for analysis, no genitourinary abnormalities were found in 294 (60%), minor genitourinary abnormalities were found in 100 (20.4%), moderate genitourinary abnormalities were found in 86 (17.6%), and major genitourinary abnormalities were found in 10 (2%). Renal cysts (n = 60, 12%) were the most common minor urologic findings. Moderate and major genitourinary findings of nephrolithiasis, adrenal adenomas, and renal masses were noted in 13.9%, 3%, and 2% of the population, respectively. The largest stone was 1.2 cm, and the smallest was 1 mm; while 59% had stones < 3mm, 20% between 3 mm and 5 mm, 18% between 5 mm and 10 mm, and 3% > 10 mm in size. Unilateral stones were found in 85%, while bilateral were found in 15%, and the average number of stones was 2, (range 1 - 16). Age and male sex were significantly associated with moderate or major genitourinary findings p = 0.04 and p = 0.05, respectively.

CT colonography in an asymptomatic screening population helped to identify nephrolithiasis in 13.9%. Moderate and major urologic abnormalities were found in 20% of the cohort. Risk factors included male sex and older age.