"Silent" kidney stones, those that cause no symptoms, are often found when an X-ray is taken during a health exam. Other people have their stones diagnosed when sudden pain occurs while the stone is passing, and medical attention is needed.
When a person has blood in the urine (hematuria) or sudden abdominal or side pain, tests like an ultrasound or a CT scan may diagnose a stone. These imaging tests tell the health care provider how big the stone is and where it is located.
A CT scan is often used in the ER when a stone is suspected. It is used because it can make a quick and exact diagnosis.