A self-expanding cannula providing a conduit through a skin between an inside of a corpus and an outside of the corpus is disclosed. The self-expanding cannula includes a body encompassing a lumen, and has a distal-end to be positioned outside of the corpus for attachment to an extracorporeal fluid handling system and having a proximal-end to be positioned inside of the corpus, for attachment to an organ of an human or an animal. The body of the self-expanding cannula is constructed from a braided-wire, so that the self-expanding cannula is capable of expanding from a closed diameter to an opened diameter. A catheter-sheath and a catheter-sheath-assembly as well as to a method for applying and positioning a self-expanding cannula, and a catheter-sheath-assembly are disclosed.