An IV catheter insertion device includes a flash chamber into which blood (or other fluid) flows to confirm the proper placement of the catheter. Within the device is a movable member which is controlled from outside, as by a health care worker moving a plunger to move the movable member and expel blood from the flash chamber through the needle for testing or other analysis. The plunger may have a locking and unlocking mechanism to present the movement of the plunger from occurring when it is not desired.
