Combining history of present illness and review of systems is possible when doing medical billing. Many medical billers think this practice is breaking a rule or impossible. However, documenting an element once to account for HPI and ROS is perfectly legal when done correctly. The CMS states that physicians absolutely do not need to document an element two times just so the person performing medical billing knows it is meant to be used both for review of systems and history of present illness. It is perfectly acceptable to use an element for both. The only time an element cannot be used twice is when you attempt to use it in …