An adaptor (1) for the valve (15) of an introducer (16) in a human or animal body,characterized in that it comprises an outer surface (2) adapted to cooperatewith the valve (15)； its interior volume (3) comprises at least one duct (4) forallowing surgical or medical instruments having an elongate body to pass through；and the duct (4) comprises waterproofing means. The duct (4) of the adaptor (1)comprises waterproofing means at its proximal end (6) and/or at its distal end(5).
