The following are CMS'documentation guidelines for the three subsequent hospital care codes: Service should be about 15 minutes long and should entail medical decision-making for limited diagnosis and management options, posing low risk. The history of present illness (HPI) should review one to three components. The examination should be limited to the affected body area or organ system. Service should be about 25 minutes long and should entail medical decision-making for multiple diagnosis and management options or a new problem, posing moderate risk. HPI should include one to three components and a review of systems (ROS) of one system. Examination is limited to the affected body area or organ system and other symptomatic or related organ system(s). Service should be about 35 minutes long and should entail medical decision-making of high complexity, meaning that it involves extensive diagnosis and treatment options, posing high risk. HPI should review four or more components with a review of symptoms in two to nine organ systems. Examination extends to the affected body area(s) and other symptomatic or related organ system(s). Note: These follow the 1995 documentation guidelines, which most physiatrists favor.