Reducing unnecessary repeat imaging may reduce waste and costs, and improve health care quality. We aimed to quantify repeat imaging rates in patients with abdominal imaging examinations, and identify factors associated with repeat imaging.

We retrospectively analyzed all diagnostic abdominal computed tomography (CT), magnetic resonance imaging (MRI), ultrasound (US), fluoroscopy, and radiograph reports performed at our institution between January 1, 2000 and December 31, 2009. Primary outcome measure was the rate of repeat abdominal imaging (RAI) examinations, defined as any imaging examination of the abdomen on the same patient within 0-90 days of the first (enrollment) examination. We used natural language processing tools to extract recommendations for follow-up imaging from radiology reports. Univariate and multivariate logistic regressions were fitted to determine the effect of patient age, sex, study modality, care setting, follow-up recommendations, and history of neoplasm on the primary outcome over time.

Over 10 years, 245,184 abdominal imaging examinations were performed (43.2% CT, 20.6% US, 16.6% radiograph, 13.9% fluoroscopy, 5.7% MRI). The RAI rate remained unchanged (41.2% to 41.7%); unadjusted RAI volume increased from 6596 to 12,218 (P <.01). Most repeat studies (88.2%) were not preceded by a radiologist's recommendation. Practice setting, study modality, patient age, sex, underlying health condition, and radiologist's recommendations were associated with higher rate of repeat abdominal imaging examinations.

A large proportion of abdominal imaging examinations result in a repeat study. Many factors contribute to repeat imaging, including patient age, sex, underlying disease, initial study modality, practice setting, and radiologist's recommendation.