A good way to prevent scope creep is to gather inputs from the customer early on in the project and lock down the scope as early as possible. I agree with cdj24 that in some cases scope creep can be unavoidable, especially considering that the medical device market is very dynamic and the scope may have to be adjusted in order for the product that you are developing to be competitive in the market once it is released. In these instances, I think it is very important that the company has a very thorough scope management plan where they can assess the proposed changes in scope, consider the timeline adjustments and business impacts, and make an informed decision whether or not it makes sense to adjust the scope. I think often the scope is adjusted hastily without putting much thought into the actual impact to the project.