Device for selective access closure inside a catheter

Obstruction device (10) for selective access closure inside a catheter comprising on the one hand a body (12) bounding a conduit (14) having a rear extremity (16) for the insertion of a medical instrument and a front extremity (18) provided with means (19) for connection to the catheter and on the other hand a mechanism (27) for adjusting the cross-section of the passage offered within the conduit (14), this adjustment mechanism (27) comprising a member (32) for repositioning the device which can move with respect to the body (12) along an opening path to change to an open condition in which the nominal passage cross-section is provided within the conduit (14) and along a closing path to change to a closed condition in which passage through the conduit (14) is at least partly obstructed, characterised in that both the direction of movement of the repositioning member (32) following the said closing path and the direction of movement of the repositioning member following the said opening path are identical.