Abstract: The disclosure relates to a medical endoscope including: a piston body in which a piston is movably mounted in displacement; the piston delimiting with the piston body a sealed obturation section and a sealed interconnection chamber adapted so that, in the open position of the obturation device, the sealed interconnection chamber ensures communication between a first portion and a second portion of the circulation circuit. According to the disclosure, the sealed interconnection chamber including a hole passing right through the piston to open out into a cylindrical chamber delimited between the piston and the piston body, by an oblong section located in the open position of the circulation circuit, facing the inlet sections of the tubing for connection to the first portion and to the second portion of the circulation circuit to limit the pressure drop.