A clinical trial is required for all new drugs, but this is not the case for all medical devices. Medical devices start by undergoing a risk assessment in order to determine the severity of potential harm to the user and the probability of that harm occurring. Each device is assigned to one of three classes based on this assessment, and this classification dictates whether or not a clinical trial is necessary.
Use this infographic as a helpful resource for understanding medical device classifications.
photo credit: derekGavey Risk Tournament via photopin (license)