Patent ID: 8167843

Claim:
A trocar comprising: a retention cannula comprising: a proximal end, a distal end, and a longitudinal axis; a cannula wall defining a lumen extending between the proximal end and the distal end; a tip disposed at the distal end of the cannula, a cannula body between the proximal end of the cannula and the tip; and an inverted, tissue retention pattern extending into the wall of the cannula body, wherein an outer diameter of the inverted pattern is not greater than an outer diameter of the cannula body; and a seal assembly coupled to the proximal end of the cannula, wherein the inverted pattern comprises a thread root defining the outer diameter of the inverted pattern and a thread tip defining the outer diameter of the cannula body, wherein the inverted pattern comprises a first plurality of thread roots extending circumferentially about the cannula wall generally perpendicularly to the longitudinal axis of the trocar, wherein the inverted pattern further comprises a second plurality of thread roots each having a retention segment extending circumferentially about the cannula wall generally perpendicularly to the longitudinal axis of the trocar, and a flow channel extending circumferentially about the cannula wall transverse to the longitudinal axis.