An obturator includes an elongate shaft extending between a proximal end and a distal end, the elongate shaft having an opening at the proximal end and defining an elongate cavity which is sized and shaped to receive an optical instrument. The obturator is provided with an axially extending finger for radial movement inwardly to engage the outer surface of the optical instrument located within the elongate cavity. The finger may be a latch member with a latch element and able to be moved between a first position, in which the latch element is located relatively radially inward, and a second position in which the latch element is located relatively radially outward. With the obturator located within a cannula body, an instrument inserted into the obturator causes the latch element of the latch member to engage with the cannula to prevent relative axial movement therebetween.
