A catheter assembly may include a catheter adapter, a septum housing, and a septum. The catheter adapter may include a distal end, a proximal end, an inner wall extending between the distal end and the proximal end, and a lumen formed by the inner wall. The septum housing may include one or more protrusions and may be secured to the inner wall by one or more of the following: an interference fit between the one or more protrusions and the inner wall, a snap fit between the one or more protrusions and the inner wall, and bonding between the one or more protrusions and the inner wall. The septum may be at least partially disposed within the septum housing and configured to at least substantially seal the lumen.