Abstract: A catheter or cannula (2) which includes a press or pinch point (18) which may be resiliently deformed to prevent flow of blood or other body fluids during insertion of the catheter or cannula tube (10) or it may be part of the boss (11) of the catheter or cannula (2). One or more protrusions or buttons (20) may be integrally moulded to the press or pinch point (18) to assist with the application of pressure to the press or pinch point (18) to prevent fluid flow. Wings (14) extending from the sides of the cannula or catheter (2) may provide support and be hinged to enable compression of the press or pinch point (18). The cathether or cannula tube (10) is of a size to fit over a hypodermic needle (5) of a trocar (1) inserted into the catheter or cannula (2).