Classification of active medical devices according to the Medical Device Directive

Under the Medical Device Directive, manufacturers must group their products into four classes--I, IIa, IIb, and III--classification being based on the degree of risk the device presents. To aid manufacturers in the application of the classification rules of the Directive, especially with regard to the combination of active and nonactive characteristics, this article provides a guideline that includes definitions and a reduced scheme for the combined characteristics of these devices.