Abstract: A cannula including a hollow cannula body having first and second tubular end portions, a collapsible section interconnecting the end portions, the collapsible section including a plurality of circumferentially spaced arms extending between the end portions, wherein in an extended configuration the arms are substantially aligned with the first and second end portions and in a collapsed configuration the arms deform to extend radially outwardly and a flange extending radially outwardly from the first end portion, so that the arms and flange are spaced apart when the cannula body is in the collapsed configuration, thereby allowing tissue to be sandwiched therebetween to thereby effect a seal between the cannula and the tissue so that the cannula provides an opening through the tissue.