Abstract
Needleless connectors have been introduced into clinical practice to prevent accidental needlestick injuries and associated bloodborne infections. Needleless connectors include the split-septum devices and the mechanical valves that are classified as neutral-, negative-, and positive-displacement types on the basis of their internal membrane or valve function. Some studies have reported that mechanical valves, especially positive-displacement valves, may decrease thrombotic catheter occlusions based on their valve function that prevents blood reflux into the intravascular catheter. This article describes the types of needleless connectors and reviews the evidence related to their effects on thrombotic catheter occlusions.