Flush syringe assemblies are described herein. Such flush syringe assembly may include a barrel including a side wall defining a chamber, a collar mounted on a distal wall of the barrel and surrounding an elongate tip. A cap may be attached to the collar via a hinge. The flush syringe assembly may also include a cap attached to the collar via a hinge. A ring may be disposed around the collar with a locking element that engages with a corresponding mating locking projection on the cap. The cap may include a slanted surface. The slanted surface of the cap may include one or more ribs made of an elastomeric material.