Trocar structure for abdominal surgery

A Trocar structure for abdominal surgery comprising a cannula (2) having at one end a guide element (3) provided with a disposable valve (5) for maintaining positive intracavitary pressure and a shaft (4) having at one end a head (6) and at the opposite end a tip (7), said valve being made of a single piece of silicone and has first elastically deformable sealing means (8) for maintaining said positive intracavitary pressure during the passage of said shaft (4) and a surgical instrument through said cannula and second sealing means (9), elastically deformable, with said guide element, characterized in that said first sealing means comprise central slits (10) oriented concentrically on a flat wall (11) of said disposable valve (5), said slits forming lobes (12) adapted to bend inside or outside said wall in a uniform manner to form on the surface of said shaft (4) and of said surgical instrument, a first collar (14) providing a continuous annular seal and in that said second sealing means (9) comprise a second collar (15) engaging elastically an annular seat (16) of said guide element, said flat wall (11) defines an entire top portion of the disposable valve (5) and having a rounded circumferential edge (17) which directly connects said flat wall (11) with a cylindrical side wall at the end of which said second collar (15) is provided, said slits (10) being arranged preferably at 120° from one another and located only in a central portion of said flat wall (11) has a surface sufficient to form the first collar (14) which sealingly surrounds an annular portion of said shaft (4) when said shaft is inserted into the disposable valve (5), said flat wall (11) and said cylindrical side wall having a constant thickness adapted to exclude the use of a reducer during the use of the Trocar.