Positioning and support device suitable to contain a distal end of an oblong article to be subjected to washing treatment, and possible sterilization and/or disinfection, comprising: a first internal tubular element defining a treatment chamber suitable to contain and house said distal end, and having an entry aperture, configured to allow the insertion in and removal from said chamber of said distal end, wherein said internal tubular element has a body onto which a plurality of through holes open; a second external tubular element, coaxially associated with said internal tubular element, so as to define with the latter a hollow space fluidically connected to said treatment chamber by means of said through holes; an entry for a treatment fluid located in correspondence with a first end of said positioning and support device, to which means (44, S) to introduce a treatment fluid can be connected, and oriented in an axial direction with respect to said hollow space and a discharge exit configured to allow the outflow of the treatment fluid from said chamber, characterized in that said entry and said discharge exit are disposed on a same end of said positioning and support device and said hollow space is at least partly closed in correspondence with the opposite end, said positioning and support device comprises a compartment to distribute the fluid that has an annular shape, delimited on one side by an external wall in which said entry is made and, on the opposite side, by an internal wall comprising at least three through slits communicating with said hollow space and said external tubular element is provided with a separating wall, or partition, defining said internal wall and comprising said exit made in a central portion thereof and said through slits disposed equally distanced around said exit. a first internal tubular element defining a treatment chamber suitable to contain and house said distal end, and having an entry aperture, configured to allow the insertion in and removal from said chamber of said distal end, wherein said internal tubular element has a body onto which a plurality of through holes open; a second external tubular element, coaxially associated with said internal tubular element, so as to define with the latter a hollow space fluidically connected to said treatment chamber by means of said through holes; an entry for a treatment fluid located in correspondence with a first end of said positioning and support device, to which means (44, S) to introduce a treatment fluid can be connected, and oriented in an axial direction with respect to said hollow space and a discharge exit configured to allow the outflow of the treatment fluid from said chamber, characterized in that said entry and said discharge exit are disposed on a same end of said positioning and support device and said hollow space is at least partly closed in correspondence with the opposite end, said positioning and support device comprises a compartment to distribute the fluid that has an annular shape, delimited on one side by an external wall in which said entry is made and, on the opposite side, by an internal wall comprising at least three through slits communicating with said hollow space and said external tubular element is provided with a separating wall, or partition, defining said internal wall and comprising said exit made in a central portion thereof and said through slits disposed equally distanced around said exit.