If there is sufficient evidence already available for a similar device, V&V will only be necessary to make sure that the device meets the user needs (validation) and that the device functions as it should (verification). However, sometimes the results from clinical trials may be necessary for design verification. In this case it would be helpful to keep in mind how a certain user need will be met when the user needs are created. With proper documentation and planning, the devices that have been mentioned should not require clinical trials.