Medical devices, assemblies and methods for guarding sharp tips of medical needles are disclosed herein. Some embodiments include an expandable device configured to be at least partially disposed within the needle lumen. The device may include an expandable distal portion that is designed to shift between a first configuration in which the expandable distal portion has an outer diameter that is the same as or less than the inner diameter of the needle lumen and a second configuration in which the expandable distal portion has an outer diameter that is greater than the inner diameter of the needle lumen. An elongated inner member may be used to shift the expandable distal portion from the first configuration to the second configuration.
