A passive intravenous (“IV”) catheter introducer having a spring-biased needle retraction system that is triggered when the needle is manually withdrawn through a catheter hub seal. The catheter hub seal constricts to block the rearward flow of bodily fluid and wipe potentially infectious fluids off the outer surface of the needle as the needle is manually withdrawn through the catheter sheath and seal following insertion of the catheter into a patients vein. No additional steps are needed to activate the needle retraction mechanism beyond manual removal of the needle from the catheter hub seal.