A catheter assembly (10) is disclosed having a catheter adapter (14) and a needle hub (45). The catheter adapter has an inner lumen (16) with a septum (50) located within the inner lumen. An introducer needle (20) is inserted through the inner lumen. A septum activator (80) also located within the inner lumen, such that a distal end of the septum activator contacts the septum. The septum activator has an internal cavity (88) and a cavity seal (131) forming a surface of the internal cavity.
