CT in detecting urinary tract calculi: influence on patient imaging and clinical outcomes

To determine changes in examination patterns and effectiveness of care since the introduction of unenhanced helical computed tomography (CT) for examination of patients presenting to the emergency department (ED) with symptoms of urinary tract calculi (UTC).

Hospital clinical and radiology information systems were used to retrospectively identify patients presenting with UTC symptoms from January to December 1997 (before introduction of unenhanced CT) and from January to December 1999 (after introduction of unenhanced CT). Chart abstraction was used to confirm the identification of patients with presenting symptoms suggestive of UTC and assess patient outcomes. Two hundred sixty-five patients presented before (1997) and 602 after (1999) unenhanced CT was introduced. Distributions of dichotomous variables were compared between the 1997 and 1999 groups by using logistic regression. Means were compared between the groups by using analysis of variance and mean total numbers of imaging studies by using Poisson regression.

Total number of imaging studies increased by 26.7% per patient visit (P <.001). Rates of admission following the initial ED visit (13.7% in 1997 vs 13.4% in 1999), as well as percentage of patients who subsequently returned to the ED (12.0% in 1997 vs 13.7% in 1999) or subsequently were admitted to the hospital (4.5% in 1997 vs 5.3% in 1999) in the month following the initial ED visit, were similar between the two groups. Unsuspected unenhanced CT findings that could affect acute patient care were observed at 5.9% of examinations.

Use of imaging for suspected UTC has increased markedly since the introduction of unenhanced CT, with little effect on acute care of patients in the ED.