A tool introducer is configured for introduction in an elongated body including a straight tube, wherein the tube encloses a tube lumen opened at its distal end with a tube opening. The tool introducer includes locking means to selectively lock or unlock an interchangeable surgical tool to the tube from displacing axially and/or rotationally in the tube lumen, the locking means being configured such that, at the locking, a tool connector of the tool projects towards the tube opening and is distanced therefrom by at least 3 cm. A method includes positioning the surgical tool introducer such that a distal portion thereof projects in a body cavity, manipulating and/or extending the tool introducer to reach and engage an elongated shaft introduced percutaneously into the body cavity; and inserting the elongated shaft into the tube lumen via the tube opening and connecting the tool to the elongated shaft.