The most common reasons for a visit to an urgent care center are when an illness or injury occurs, either after hours or when a primary doctor is unavailable, or if the illness is not life threatening but requires urgent care. The range of services offered at an urgent care center are much broader than a walk-in clinic or most family doctor offices. In addition to treating a wide range of injuries and illnesses, most urgent care centers have a wider range of diagnostic equipment, and many also have x-ray, and on-site lab testing capabilities. Overcrowding at hospital emergency rooms are largely in part due to an estimated 40 percent of patients not requiring high-level emergency care. Traumatic injuries, stroke, and heart attack are among the top serious medical issues requiring immediate, expert care in an emergency room setting.