This is a protocol for a Cochrane Review (intervention). The objectives are as follows: To assess the effects (benefits and harms) of catheter retention (or delayed removal after an initial catheter retention strategy) compared to prompt catheter replacement or removal in people of all ages with a short- or long-term central venous catheter or any arterial catheter, and either (i) catheter-related or -associated infection, (ii) bloodstream infection from an uncertain source or (iii) sepsis from