This is a multi-center, randomized controlled trial of ultrasonography compared with computed tomography (CT) for the evaluation of patients with suspected urolithiasis. The study will be conducted at 15 large urban Emergency Departments (EDs), reflecting geographic, socioeconomic, racial and ethnic diversity, and include academic medical centers as well as safety net hospitals. The patients will be randomized to one of three arms: 1) ultrasound in the Emergency Department (ED), 2) ultrasound in radiology or 3) CT in radiology. The investigators will then collect precise and unbiased data on a comprehensive range of outcomes that will allow assessment of effectiveness, safety, accuracy and cost between patients randomized to one the three groups. Taken together, these measures are intended to provide the basis for a valid comparison of imaging of patients with suspected urolithiasis seen in the ED. The results of this trial could lead to a change in clinical practice that is associated with both improved patient outcomes and reduced cost. Broad stakeholder involvement from within radiology, emergency medicine and several subspecialty communities has been sought to ensure the strategic completion of study aims and to help rapidly disseminate the results of the study into clinical practice. This will create a collaborative network of EDs willing to act as a laboratory for studying the comparative effectiveness of diagnostic testing. As a result, the proposed trial will demonstrate the feasibility of conducting Randomized Control Trials (RCTs) of imaging that incorporates measurements of outcomes that can be expanded to additional imaging tests in the future.