A catheter assembly may include a catheter adapter, which may include a distal end, a proximal end, and a lumen extending therethrough. The catheter assembly may also include a septum slidably disposed within the lumen. The septum may include a distal end, a proximal end, and a barrier disposed between the distal end of the septum and the proximal end of the septum. The barrier may divide an interior of the septum into a distal cavity and a proximal cavity. A distal face of the barrier may include a protrusion. The barrier may include a slit extending through the protrusion for selectively opening fluid communication between the distal cavity and the proximal cavity.